{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE NamedFieldPuns #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE StrictData #-}
{-# LANGUAGE NoImplicitPrelude #-}
{-# OPTIONS_GHC -fno-warn-unused-imports #-}
{-# OPTIONS_GHC -fno-warn-unused-matches #-}

-- Derived from AWS service descriptions, licensed under Apache 2.0.

-- |
-- Module      : Amazonka.DynamoDB.Types.ExpectedAttributeValue
-- Copyright   : (c) 2013-2023 Brendan Hay
-- License     : Mozilla Public License, v. 2.0.
-- Maintainer  : Brendan Hay
-- Stability   : auto-generated
-- Portability : non-portable (GHC extensions)
module Amazonka.DynamoDB.Types.ExpectedAttributeValue where

import qualified Amazonka.Core as Core
import qualified Amazonka.Core.Lens.Internal as Lens
import qualified Amazonka.Data as Data
import Amazonka.DynamoDB.Types.AttributeValue
import Amazonka.DynamoDB.Types.ComparisonOperator
import Amazonka.DynamoDB.Types.WriteRequest
import qualified Amazonka.Prelude as Prelude

-- | Represents a condition to be compared with an attribute value. This
-- condition can be used with @DeleteItem@, @PutItem@, or @UpdateItem@
-- operations; if the comparison evaluates to true, the operation succeeds;
-- if not, the operation fails. You can use @ExpectedAttributeValue@ in one
-- of two different ways:
--
-- -   Use @AttributeValueList@ to specify one or more values to compare
--     against an attribute. Use @ComparisonOperator@ to specify how you
--     want to perform the comparison. If the comparison evaluates to true,
--     then the conditional operation succeeds.
--
-- -   Use @Value@ to specify a value that DynamoDB will compare against an
--     attribute. If the values match, then @ExpectedAttributeValue@
--     evaluates to true and the conditional operation succeeds.
--     Optionally, you can also set @Exists@ to false, indicating that you
--     /do not/ expect to find the attribute value in the table. In this
--     case, the conditional operation succeeds only if the comparison
--     evaluates to false.
--
-- @Value@ and @Exists@ are incompatible with @AttributeValueList@ and
-- @ComparisonOperator@. Note that if you use both sets of parameters at
-- once, DynamoDB will return a @ValidationException@ exception.
--
-- /See:/ 'newExpectedAttributeValue' smart constructor.
data ExpectedAttributeValue = ExpectedAttributeValue'
  { -- | One or more values to evaluate against the supplied attribute. The
    -- number of values in the list depends on the @ComparisonOperator@ being
    -- used.
    --
    -- For type Number, value comparisons are numeric.
    --
    -- String value comparisons for greater than, equals, or less than are
    -- based on ASCII character code values. For example, @a@ is greater than
    -- @A@, and @a@ is greater than @B@. For a list of code values, see
    -- <http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters>.
    --
    -- For Binary, DynamoDB treats each byte of the binary data as unsigned
    -- when it compares binary values.
    --
    -- For information on specifying data types in JSON, see
    -- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DataFormat.html JSON Data Format>
    -- in the /Amazon DynamoDB Developer Guide/.
    ExpectedAttributeValue -> Maybe [AttributeValue]
attributeValueList :: Prelude.Maybe [AttributeValue],
    -- | A comparator for evaluating attributes in the @AttributeValueList@. For
    -- example, equals, greater than, less than, etc.
    --
    -- The following comparison operators are available:
    --
    -- @EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN@
    --
    -- The following are descriptions of each comparison operator.
    --
    -- -   @EQ@ : Equal. @EQ@ is supported for all data types, including lists
    --     and maps.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, Binary, String Set, Number Set, or Binary
    --     Set. If an item contains an @AttributeValue@ element of a different
    --     type than the one provided in the request, the value does not match.
    --     For example, @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @NE@ : Not equal. @NE@ is supported for all data types, including
    --     lists and maps.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ of type
    --     String, Number, Binary, String Set, Number Set, or Binary Set. If an
    --     item contains an @AttributeValue@ of a different type than the one
    --     provided in the request, the value does not match. For example,
    --     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @LE@ : Less than or equal.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, or Binary (not a set type). If an item
    --     contains an @AttributeValue@ element of a different type than the
    --     one provided in the request, the value does not match. For example,
    --     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not compare to
    --     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @LT@ : Less than.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ of type
    --     String, Number, or Binary (not a set type). If an item contains an
    --     @AttributeValue@ element of a different type than the one provided
    --     in the request, the value does not match. For example,
    --     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not compare to
    --     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @GE@ : Greater than or equal.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, or Binary (not a set type). If an item
    --     contains an @AttributeValue@ element of a different type than the
    --     one provided in the request, the value does not match. For example,
    --     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not compare to
    --     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @GT@ : Greater than.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, or Binary (not a set type). If an item
    --     contains an @AttributeValue@ element of a different type than the
    --     one provided in the request, the value does not match. For example,
    --     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
    --     @{\"N\":\"6\"}@ does not compare to
    --     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
    --
    -- -   @NOT_NULL@ : The attribute exists. @NOT_NULL@ is supported for all
    --     data types, including lists and maps.
    --
    --     This operator tests for the existence of an attribute, not its data
    --     type. If the data type of attribute \"@a@\" is null, and you
    --     evaluate it using @NOT_NULL@, the result is a Boolean @true@. This
    --     result is because the attribute \"@a@\" exists; its data type is not
    --     relevant to the @NOT_NULL@ comparison operator.
    --
    -- -   @NULL@ : The attribute does not exist. @NULL@ is supported for all
    --     data types, including lists and maps.
    --
    --     This operator tests for the nonexistence of an attribute, not its
    --     data type. If the data type of attribute \"@a@\" is null, and you
    --     evaluate it using @NULL@, the result is a Boolean @false@. This is
    --     because the attribute \"@a@\" exists; its data type is not relevant
    --     to the @NULL@ comparison operator.
    --
    -- -   @CONTAINS@ : Checks for a subsequence, or value in a set.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, or Binary (not a set type). If the target
    --     attribute of the comparison is of type String, then the operator
    --     checks for a substring match. If the target attribute of the
    --     comparison is of type Binary, then the operator looks for a
    --     subsequence of the target that matches the input. If the target
    --     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
    --     \"@BS@\"), then the operator evaluates to true if it finds an exact
    --     match with any member of the set.
    --
    --     CONTAINS is supported for lists: When evaluating \"@a CONTAINS b@\",
    --     \"@a@\" can be a list; however, \"@b@\" cannot be a set, a map, or a
    --     list.
    --
    -- -   @NOT_CONTAINS@ : Checks for absence of a subsequence, or absence of
    --     a value in a set.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ element
    --     of type String, Number, or Binary (not a set type). If the target
    --     attribute of the comparison is a String, then the operator checks
    --     for the absence of a substring match. If the target attribute of the
    --     comparison is Binary, then the operator checks for the absence of a
    --     subsequence of the target that matches the input. If the target
    --     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
    --     \"@BS@\"), then the operator evaluates to true if it /does not/ find
    --     an exact match with any member of the set.
    --
    --     NOT_CONTAINS is supported for lists: When evaluating
    --     \"@a NOT CONTAINS b@\", \"@a@\" can be a list; however, \"@b@\"
    --     cannot be a set, a map, or a list.
    --
    -- -   @BEGINS_WITH@ : Checks for a prefix.
    --
    --     @AttributeValueList@ can contain only one @AttributeValue@ of type
    --     String or Binary (not a Number or a set type). The target attribute
    --     of the comparison must be of type String or Binary (not a Number or
    --     a set type).
    --
    -- -   @IN@ : Checks for matching elements in a list.
    --
    --     @AttributeValueList@ can contain one or more @AttributeValue@
    --     elements of type String, Number, or Binary. These attributes are
    --     compared against an existing attribute of an item. If any elements
    --     of the input are equal to the item attribute, the expression
    --     evaluates to true.
    --
    -- -   @BETWEEN@ : Greater than or equal to the first value, and less than
    --     or equal to the second value.
    --
    --     @AttributeValueList@ must contain two @AttributeValue@ elements of
    --     the same type, either String, Number, or Binary (not a set type). A
    --     target attribute matches if the target value is greater than, or
    --     equal to, the first element and less than, or equal to, the second
    --     element. If an item contains an @AttributeValue@ element of a
    --     different type than the one provided in the request, the value does
    --     not match. For example, @{\"S\":\"6\"}@ does not compare to
    --     @{\"N\":\"6\"}@. Also, @{\"N\":\"6\"}@ does not compare to
    --     @{\"NS\":[\"6\", \"2\", \"1\"]}@
    ExpectedAttributeValue -> Maybe ComparisonOperator
comparisonOperator :: Prelude.Maybe ComparisonOperator,
    -- | Causes DynamoDB to evaluate the value before attempting a conditional
    -- operation:
    --
    -- -   If @Exists@ is @true@, DynamoDB will check to see if that attribute
    --     value already exists in the table. If it is found, then the
    --     operation succeeds. If it is not found, the operation fails with a
    --     @ConditionCheckFailedException@.
    --
    -- -   If @Exists@ is @false@, DynamoDB assumes that the attribute value
    --     does not exist in the table. If in fact the value does not exist,
    --     then the assumption is valid and the operation succeeds. If the
    --     value is found, despite the assumption that it does not exist, the
    --     operation fails with a @ConditionCheckFailedException@.
    --
    -- The default setting for @Exists@ is @true@. If you supply a @Value@ all
    -- by itself, DynamoDB assumes the attribute exists: You don\'t have to set
    -- @Exists@ to @true@, because it is implied.
    --
    -- DynamoDB returns a @ValidationException@ if:
    --
    -- -   @Exists@ is @true@ but there is no @Value@ to check. (You expect a
    --     value to exist, but don\'t specify what that value is.)
    --
    -- -   @Exists@ is @false@ but you also provide a @Value@. (You cannot
    --     expect an attribute to have a value, while also expecting it not to
    --     exist.)
    ExpectedAttributeValue -> Maybe Bool
exists :: Prelude.Maybe Prelude.Bool,
    -- | Represents the data for the expected attribute.
    --
    -- Each attribute value is described as a name-value pair. The name is the
    -- data type, and the value is the data itself.
    --
    -- For more information, see
    -- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes Data Types>
    -- in the /Amazon DynamoDB Developer Guide/.
    ExpectedAttributeValue -> Maybe AttributeValue
value :: Prelude.Maybe AttributeValue
  }
  deriving (ExpectedAttributeValue -> ExpectedAttributeValue -> Bool
forall a. (a -> a -> Bool) -> (a -> a -> Bool) -> Eq a
/= :: ExpectedAttributeValue -> ExpectedAttributeValue -> Bool
$c/= :: ExpectedAttributeValue -> ExpectedAttributeValue -> Bool
== :: ExpectedAttributeValue -> ExpectedAttributeValue -> Bool
$c== :: ExpectedAttributeValue -> ExpectedAttributeValue -> Bool
Prelude.Eq, ReadPrec [ExpectedAttributeValue]
ReadPrec ExpectedAttributeValue
Int -> ReadS ExpectedAttributeValue
ReadS [ExpectedAttributeValue]
forall a.
(Int -> ReadS a)
-> ReadS [a] -> ReadPrec a -> ReadPrec [a] -> Read a
readListPrec :: ReadPrec [ExpectedAttributeValue]
$creadListPrec :: ReadPrec [ExpectedAttributeValue]
readPrec :: ReadPrec ExpectedAttributeValue
$creadPrec :: ReadPrec ExpectedAttributeValue
readList :: ReadS [ExpectedAttributeValue]
$creadList :: ReadS [ExpectedAttributeValue]
readsPrec :: Int -> ReadS ExpectedAttributeValue
$creadsPrec :: Int -> ReadS ExpectedAttributeValue
Prelude.Read, Int -> ExpectedAttributeValue -> ShowS
[ExpectedAttributeValue] -> ShowS
ExpectedAttributeValue -> String
forall a.
(Int -> a -> ShowS) -> (a -> String) -> ([a] -> ShowS) -> Show a
showList :: [ExpectedAttributeValue] -> ShowS
$cshowList :: [ExpectedAttributeValue] -> ShowS
show :: ExpectedAttributeValue -> String
$cshow :: ExpectedAttributeValue -> String
showsPrec :: Int -> ExpectedAttributeValue -> ShowS
$cshowsPrec :: Int -> ExpectedAttributeValue -> ShowS
Prelude.Show, forall x. Rep ExpectedAttributeValue x -> ExpectedAttributeValue
forall x. ExpectedAttributeValue -> Rep ExpectedAttributeValue x
forall a.
(forall x. a -> Rep a x) -> (forall x. Rep a x -> a) -> Generic a
$cto :: forall x. Rep ExpectedAttributeValue x -> ExpectedAttributeValue
$cfrom :: forall x. ExpectedAttributeValue -> Rep ExpectedAttributeValue x
Prelude.Generic)

-- |
-- Create a value of 'ExpectedAttributeValue' with all optional fields omitted.
--
-- Use <https://hackage.haskell.org/package/generic-lens generic-lens> or <https://hackage.haskell.org/package/optics optics> to modify other optional fields.
--
-- The following record fields are available, with the corresponding lenses provided
-- for backwards compatibility:
--
-- 'attributeValueList', 'expectedAttributeValue_attributeValueList' - One or more values to evaluate against the supplied attribute. The
-- number of values in the list depends on the @ComparisonOperator@ being
-- used.
--
-- For type Number, value comparisons are numeric.
--
-- String value comparisons for greater than, equals, or less than are
-- based on ASCII character code values. For example, @a@ is greater than
-- @A@, and @a@ is greater than @B@. For a list of code values, see
-- <http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters>.
--
-- For Binary, DynamoDB treats each byte of the binary data as unsigned
-- when it compares binary values.
--
-- For information on specifying data types in JSON, see
-- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DataFormat.html JSON Data Format>
-- in the /Amazon DynamoDB Developer Guide/.
--
-- 'comparisonOperator', 'expectedAttributeValue_comparisonOperator' - A comparator for evaluating attributes in the @AttributeValueList@. For
-- example, equals, greater than, less than, etc.
--
-- The following comparison operators are available:
--
-- @EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN@
--
-- The following are descriptions of each comparison operator.
--
-- -   @EQ@ : Equal. @EQ@ is supported for all data types, including lists
--     and maps.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, Binary, String Set, Number Set, or Binary
--     Set. If an item contains an @AttributeValue@ element of a different
--     type than the one provided in the request, the value does not match.
--     For example, @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @NE@ : Not equal. @NE@ is supported for all data types, including
--     lists and maps.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String, Number, Binary, String Set, Number Set, or Binary Set. If an
--     item contains an @AttributeValue@ of a different type than the one
--     provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @LE@ : Less than or equal.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @LT@ : Less than.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String, Number, or Binary (not a set type). If an item contains an
--     @AttributeValue@ element of a different type than the one provided
--     in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @GE@ : Greater than or equal.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @GT@ : Greater than.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @NOT_NULL@ : The attribute exists. @NOT_NULL@ is supported for all
--     data types, including lists and maps.
--
--     This operator tests for the existence of an attribute, not its data
--     type. If the data type of attribute \"@a@\" is null, and you
--     evaluate it using @NOT_NULL@, the result is a Boolean @true@. This
--     result is because the attribute \"@a@\" exists; its data type is not
--     relevant to the @NOT_NULL@ comparison operator.
--
-- -   @NULL@ : The attribute does not exist. @NULL@ is supported for all
--     data types, including lists and maps.
--
--     This operator tests for the nonexistence of an attribute, not its
--     data type. If the data type of attribute \"@a@\" is null, and you
--     evaluate it using @NULL@, the result is a Boolean @false@. This is
--     because the attribute \"@a@\" exists; its data type is not relevant
--     to the @NULL@ comparison operator.
--
-- -   @CONTAINS@ : Checks for a subsequence, or value in a set.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If the target
--     attribute of the comparison is of type String, then the operator
--     checks for a substring match. If the target attribute of the
--     comparison is of type Binary, then the operator looks for a
--     subsequence of the target that matches the input. If the target
--     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
--     \"@BS@\"), then the operator evaluates to true if it finds an exact
--     match with any member of the set.
--
--     CONTAINS is supported for lists: When evaluating \"@a CONTAINS b@\",
--     \"@a@\" can be a list; however, \"@b@\" cannot be a set, a map, or a
--     list.
--
-- -   @NOT_CONTAINS@ : Checks for absence of a subsequence, or absence of
--     a value in a set.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If the target
--     attribute of the comparison is a String, then the operator checks
--     for the absence of a substring match. If the target attribute of the
--     comparison is Binary, then the operator checks for the absence of a
--     subsequence of the target that matches the input. If the target
--     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
--     \"@BS@\"), then the operator evaluates to true if it /does not/ find
--     an exact match with any member of the set.
--
--     NOT_CONTAINS is supported for lists: When evaluating
--     \"@a NOT CONTAINS b@\", \"@a@\" can be a list; however, \"@b@\"
--     cannot be a set, a map, or a list.
--
-- -   @BEGINS_WITH@ : Checks for a prefix.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String or Binary (not a Number or a set type). The target attribute
--     of the comparison must be of type String or Binary (not a Number or
--     a set type).
--
-- -   @IN@ : Checks for matching elements in a list.
--
--     @AttributeValueList@ can contain one or more @AttributeValue@
--     elements of type String, Number, or Binary. These attributes are
--     compared against an existing attribute of an item. If any elements
--     of the input are equal to the item attribute, the expression
--     evaluates to true.
--
-- -   @BETWEEN@ : Greater than or equal to the first value, and less than
--     or equal to the second value.
--
--     @AttributeValueList@ must contain two @AttributeValue@ elements of
--     the same type, either String, Number, or Binary (not a set type). A
--     target attribute matches if the target value is greater than, or
--     equal to, the first element and less than, or equal to, the second
--     element. If an item contains an @AttributeValue@ element of a
--     different type than the one provided in the request, the value does
--     not match. For example, @{\"S\":\"6\"}@ does not compare to
--     @{\"N\":\"6\"}@. Also, @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@
--
-- 'exists', 'expectedAttributeValue_exists' - Causes DynamoDB to evaluate the value before attempting a conditional
-- operation:
--
-- -   If @Exists@ is @true@, DynamoDB will check to see if that attribute
--     value already exists in the table. If it is found, then the
--     operation succeeds. If it is not found, the operation fails with a
--     @ConditionCheckFailedException@.
--
-- -   If @Exists@ is @false@, DynamoDB assumes that the attribute value
--     does not exist in the table. If in fact the value does not exist,
--     then the assumption is valid and the operation succeeds. If the
--     value is found, despite the assumption that it does not exist, the
--     operation fails with a @ConditionCheckFailedException@.
--
-- The default setting for @Exists@ is @true@. If you supply a @Value@ all
-- by itself, DynamoDB assumes the attribute exists: You don\'t have to set
-- @Exists@ to @true@, because it is implied.
--
-- DynamoDB returns a @ValidationException@ if:
--
-- -   @Exists@ is @true@ but there is no @Value@ to check. (You expect a
--     value to exist, but don\'t specify what that value is.)
--
-- -   @Exists@ is @false@ but you also provide a @Value@. (You cannot
--     expect an attribute to have a value, while also expecting it not to
--     exist.)
--
-- 'value', 'expectedAttributeValue_value' - Represents the data for the expected attribute.
--
-- Each attribute value is described as a name-value pair. The name is the
-- data type, and the value is the data itself.
--
-- For more information, see
-- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes Data Types>
-- in the /Amazon DynamoDB Developer Guide/.
newExpectedAttributeValue ::
  ExpectedAttributeValue
newExpectedAttributeValue :: ExpectedAttributeValue
newExpectedAttributeValue =
  ExpectedAttributeValue'
    { $sel:attributeValueList:ExpectedAttributeValue' :: Maybe [AttributeValue]
attributeValueList =
        forall a. Maybe a
Prelude.Nothing,
      $sel:comparisonOperator:ExpectedAttributeValue' :: Maybe ComparisonOperator
comparisonOperator = forall a. Maybe a
Prelude.Nothing,
      $sel:exists:ExpectedAttributeValue' :: Maybe Bool
exists = forall a. Maybe a
Prelude.Nothing,
      $sel:value:ExpectedAttributeValue' :: Maybe AttributeValue
value = forall a. Maybe a
Prelude.Nothing
    }

-- | One or more values to evaluate against the supplied attribute. The
-- number of values in the list depends on the @ComparisonOperator@ being
-- used.
--
-- For type Number, value comparisons are numeric.
--
-- String value comparisons for greater than, equals, or less than are
-- based on ASCII character code values. For example, @a@ is greater than
-- @A@, and @a@ is greater than @B@. For a list of code values, see
-- <http://en.wikipedia.org/wiki/ASCII#ASCII_printable_characters>.
--
-- For Binary, DynamoDB treats each byte of the binary data as unsigned
-- when it compares binary values.
--
-- For information on specifying data types in JSON, see
-- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/DataFormat.html JSON Data Format>
-- in the /Amazon DynamoDB Developer Guide/.
expectedAttributeValue_attributeValueList :: Lens.Lens' ExpectedAttributeValue (Prelude.Maybe [AttributeValue])
expectedAttributeValue_attributeValueList :: Lens' ExpectedAttributeValue (Maybe [AttributeValue])
expectedAttributeValue_attributeValueList = forall s a b t. (s -> a) -> (s -> b -> t) -> Lens s t a b
Lens.lens (\ExpectedAttributeValue' {Maybe [AttributeValue]
attributeValueList :: Maybe [AttributeValue]
$sel:attributeValueList:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe [AttributeValue]
attributeValueList} -> Maybe [AttributeValue]
attributeValueList) (\s :: ExpectedAttributeValue
s@ExpectedAttributeValue' {} Maybe [AttributeValue]
a -> ExpectedAttributeValue
s {$sel:attributeValueList:ExpectedAttributeValue' :: Maybe [AttributeValue]
attributeValueList = Maybe [AttributeValue]
a} :: ExpectedAttributeValue) forall b c a. (b -> c) -> (a -> b) -> a -> c
Prelude.. forall (f :: * -> *) (g :: * -> *) s t a b.
(Functor f, Functor g) =>
AnIso s t a b -> Iso (f s) (g t) (f a) (g b)
Lens.mapping forall s t a b. (Coercible s a, Coercible t b) => Iso s t a b
Lens.coerced

-- | A comparator for evaluating attributes in the @AttributeValueList@. For
-- example, equals, greater than, less than, etc.
--
-- The following comparison operators are available:
--
-- @EQ | NE | LE | LT | GE | GT | NOT_NULL | NULL | CONTAINS | NOT_CONTAINS | BEGINS_WITH | IN | BETWEEN@
--
-- The following are descriptions of each comparison operator.
--
-- -   @EQ@ : Equal. @EQ@ is supported for all data types, including lists
--     and maps.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, Binary, String Set, Number Set, or Binary
--     Set. If an item contains an @AttributeValue@ element of a different
--     type than the one provided in the request, the value does not match.
--     For example, @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @NE@ : Not equal. @NE@ is supported for all data types, including
--     lists and maps.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String, Number, Binary, String Set, Number Set, or Binary Set. If an
--     item contains an @AttributeValue@ of a different type than the one
--     provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not equal @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @LE@ : Less than or equal.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @LT@ : Less than.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String, Number, or Binary (not a set type). If an item contains an
--     @AttributeValue@ element of a different type than the one provided
--     in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @GE@ : Greater than or equal.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @GT@ : Greater than.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If an item
--     contains an @AttributeValue@ element of a different type than the
--     one provided in the request, the value does not match. For example,
--     @{\"S\":\"6\"}@ does not equal @{\"N\":\"6\"}@. Also,
--     @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@.
--
-- -   @NOT_NULL@ : The attribute exists. @NOT_NULL@ is supported for all
--     data types, including lists and maps.
--
--     This operator tests for the existence of an attribute, not its data
--     type. If the data type of attribute \"@a@\" is null, and you
--     evaluate it using @NOT_NULL@, the result is a Boolean @true@. This
--     result is because the attribute \"@a@\" exists; its data type is not
--     relevant to the @NOT_NULL@ comparison operator.
--
-- -   @NULL@ : The attribute does not exist. @NULL@ is supported for all
--     data types, including lists and maps.
--
--     This operator tests for the nonexistence of an attribute, not its
--     data type. If the data type of attribute \"@a@\" is null, and you
--     evaluate it using @NULL@, the result is a Boolean @false@. This is
--     because the attribute \"@a@\" exists; its data type is not relevant
--     to the @NULL@ comparison operator.
--
-- -   @CONTAINS@ : Checks for a subsequence, or value in a set.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If the target
--     attribute of the comparison is of type String, then the operator
--     checks for a substring match. If the target attribute of the
--     comparison is of type Binary, then the operator looks for a
--     subsequence of the target that matches the input. If the target
--     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
--     \"@BS@\"), then the operator evaluates to true if it finds an exact
--     match with any member of the set.
--
--     CONTAINS is supported for lists: When evaluating \"@a CONTAINS b@\",
--     \"@a@\" can be a list; however, \"@b@\" cannot be a set, a map, or a
--     list.
--
-- -   @NOT_CONTAINS@ : Checks for absence of a subsequence, or absence of
--     a value in a set.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ element
--     of type String, Number, or Binary (not a set type). If the target
--     attribute of the comparison is a String, then the operator checks
--     for the absence of a substring match. If the target attribute of the
--     comparison is Binary, then the operator checks for the absence of a
--     subsequence of the target that matches the input. If the target
--     attribute of the comparison is a set (\"@SS@\", \"@NS@\", or
--     \"@BS@\"), then the operator evaluates to true if it /does not/ find
--     an exact match with any member of the set.
--
--     NOT_CONTAINS is supported for lists: When evaluating
--     \"@a NOT CONTAINS b@\", \"@a@\" can be a list; however, \"@b@\"
--     cannot be a set, a map, or a list.
--
-- -   @BEGINS_WITH@ : Checks for a prefix.
--
--     @AttributeValueList@ can contain only one @AttributeValue@ of type
--     String or Binary (not a Number or a set type). The target attribute
--     of the comparison must be of type String or Binary (not a Number or
--     a set type).
--
-- -   @IN@ : Checks for matching elements in a list.
--
--     @AttributeValueList@ can contain one or more @AttributeValue@
--     elements of type String, Number, or Binary. These attributes are
--     compared against an existing attribute of an item. If any elements
--     of the input are equal to the item attribute, the expression
--     evaluates to true.
--
-- -   @BETWEEN@ : Greater than or equal to the first value, and less than
--     or equal to the second value.
--
--     @AttributeValueList@ must contain two @AttributeValue@ elements of
--     the same type, either String, Number, or Binary (not a set type). A
--     target attribute matches if the target value is greater than, or
--     equal to, the first element and less than, or equal to, the second
--     element. If an item contains an @AttributeValue@ element of a
--     different type than the one provided in the request, the value does
--     not match. For example, @{\"S\":\"6\"}@ does not compare to
--     @{\"N\":\"6\"}@. Also, @{\"N\":\"6\"}@ does not compare to
--     @{\"NS\":[\"6\", \"2\", \"1\"]}@
expectedAttributeValue_comparisonOperator :: Lens.Lens' ExpectedAttributeValue (Prelude.Maybe ComparisonOperator)
expectedAttributeValue_comparisonOperator :: Lens' ExpectedAttributeValue (Maybe ComparisonOperator)
expectedAttributeValue_comparisonOperator = forall s a b t. (s -> a) -> (s -> b -> t) -> Lens s t a b
Lens.lens (\ExpectedAttributeValue' {Maybe ComparisonOperator
comparisonOperator :: Maybe ComparisonOperator
$sel:comparisonOperator:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe ComparisonOperator
comparisonOperator} -> Maybe ComparisonOperator
comparisonOperator) (\s :: ExpectedAttributeValue
s@ExpectedAttributeValue' {} Maybe ComparisonOperator
a -> ExpectedAttributeValue
s {$sel:comparisonOperator:ExpectedAttributeValue' :: Maybe ComparisonOperator
comparisonOperator = Maybe ComparisonOperator
a} :: ExpectedAttributeValue)

-- | Causes DynamoDB to evaluate the value before attempting a conditional
-- operation:
--
-- -   If @Exists@ is @true@, DynamoDB will check to see if that attribute
--     value already exists in the table. If it is found, then the
--     operation succeeds. If it is not found, the operation fails with a
--     @ConditionCheckFailedException@.
--
-- -   If @Exists@ is @false@, DynamoDB assumes that the attribute value
--     does not exist in the table. If in fact the value does not exist,
--     then the assumption is valid and the operation succeeds. If the
--     value is found, despite the assumption that it does not exist, the
--     operation fails with a @ConditionCheckFailedException@.
--
-- The default setting for @Exists@ is @true@. If you supply a @Value@ all
-- by itself, DynamoDB assumes the attribute exists: You don\'t have to set
-- @Exists@ to @true@, because it is implied.
--
-- DynamoDB returns a @ValidationException@ if:
--
-- -   @Exists@ is @true@ but there is no @Value@ to check. (You expect a
--     value to exist, but don\'t specify what that value is.)
--
-- -   @Exists@ is @false@ but you also provide a @Value@. (You cannot
--     expect an attribute to have a value, while also expecting it not to
--     exist.)
expectedAttributeValue_exists :: Lens.Lens' ExpectedAttributeValue (Prelude.Maybe Prelude.Bool)
expectedAttributeValue_exists :: Lens' ExpectedAttributeValue (Maybe Bool)
expectedAttributeValue_exists = forall s a b t. (s -> a) -> (s -> b -> t) -> Lens s t a b
Lens.lens (\ExpectedAttributeValue' {Maybe Bool
exists :: Maybe Bool
$sel:exists:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe Bool
exists} -> Maybe Bool
exists) (\s :: ExpectedAttributeValue
s@ExpectedAttributeValue' {} Maybe Bool
a -> ExpectedAttributeValue
s {$sel:exists:ExpectedAttributeValue' :: Maybe Bool
exists = Maybe Bool
a} :: ExpectedAttributeValue)

-- | Represents the data for the expected attribute.
--
-- Each attribute value is described as a name-value pair. The name is the
-- data type, and the value is the data itself.
--
-- For more information, see
-- <https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/HowItWorks.NamingRulesDataTypes.html#HowItWorks.DataTypes Data Types>
-- in the /Amazon DynamoDB Developer Guide/.
expectedAttributeValue_value :: Lens.Lens' ExpectedAttributeValue (Prelude.Maybe AttributeValue)
expectedAttributeValue_value :: Lens' ExpectedAttributeValue (Maybe AttributeValue)
expectedAttributeValue_value = forall s a b t. (s -> a) -> (s -> b -> t) -> Lens s t a b
Lens.lens (\ExpectedAttributeValue' {Maybe AttributeValue
value :: Maybe AttributeValue
$sel:value:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe AttributeValue
value} -> Maybe AttributeValue
value) (\s :: ExpectedAttributeValue
s@ExpectedAttributeValue' {} Maybe AttributeValue
a -> ExpectedAttributeValue
s {$sel:value:ExpectedAttributeValue' :: Maybe AttributeValue
value = Maybe AttributeValue
a} :: ExpectedAttributeValue)

instance Prelude.Hashable ExpectedAttributeValue where
  hashWithSalt :: Int -> ExpectedAttributeValue -> Int
hashWithSalt Int
_salt ExpectedAttributeValue' {Maybe Bool
Maybe [AttributeValue]
Maybe AttributeValue
Maybe ComparisonOperator
value :: Maybe AttributeValue
exists :: Maybe Bool
comparisonOperator :: Maybe ComparisonOperator
attributeValueList :: Maybe [AttributeValue]
$sel:value:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe AttributeValue
$sel:exists:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe Bool
$sel:comparisonOperator:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe ComparisonOperator
$sel:attributeValueList:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe [AttributeValue]
..} =
    Int
_salt
      forall a. Hashable a => Int -> a -> Int
`Prelude.hashWithSalt` Maybe [AttributeValue]
attributeValueList
      forall a. Hashable a => Int -> a -> Int
`Prelude.hashWithSalt` Maybe ComparisonOperator
comparisonOperator
      forall a. Hashable a => Int -> a -> Int
`Prelude.hashWithSalt` Maybe Bool
exists
      forall a. Hashable a => Int -> a -> Int
`Prelude.hashWithSalt` Maybe AttributeValue
value

instance Prelude.NFData ExpectedAttributeValue where
  rnf :: ExpectedAttributeValue -> ()
rnf ExpectedAttributeValue' {Maybe Bool
Maybe [AttributeValue]
Maybe AttributeValue
Maybe ComparisonOperator
value :: Maybe AttributeValue
exists :: Maybe Bool
comparisonOperator :: Maybe ComparisonOperator
attributeValueList :: Maybe [AttributeValue]
$sel:value:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe AttributeValue
$sel:exists:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe Bool
$sel:comparisonOperator:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe ComparisonOperator
$sel:attributeValueList:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe [AttributeValue]
..} =
    forall a. NFData a => a -> ()
Prelude.rnf Maybe [AttributeValue]
attributeValueList
      seq :: forall a b. a -> b -> b
`Prelude.seq` forall a. NFData a => a -> ()
Prelude.rnf Maybe ComparisonOperator
comparisonOperator
      seq :: forall a b. a -> b -> b
`Prelude.seq` forall a. NFData a => a -> ()
Prelude.rnf Maybe Bool
exists
      seq :: forall a b. a -> b -> b
`Prelude.seq` forall a. NFData a => a -> ()
Prelude.rnf Maybe AttributeValue
value

instance Data.ToJSON ExpectedAttributeValue where
  toJSON :: ExpectedAttributeValue -> Value
toJSON ExpectedAttributeValue' {Maybe Bool
Maybe [AttributeValue]
Maybe AttributeValue
Maybe ComparisonOperator
value :: Maybe AttributeValue
exists :: Maybe Bool
comparisonOperator :: Maybe ComparisonOperator
attributeValueList :: Maybe [AttributeValue]
$sel:value:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe AttributeValue
$sel:exists:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe Bool
$sel:comparisonOperator:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe ComparisonOperator
$sel:attributeValueList:ExpectedAttributeValue' :: ExpectedAttributeValue -> Maybe [AttributeValue]
..} =
    [Pair] -> Value
Data.object
      ( forall a. [Maybe a] -> [a]
Prelude.catMaybes
          [ (Key
"AttributeValueList" forall kv v. (KeyValue kv, ToJSON v) => Key -> v -> kv
Data..=)
              forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
Prelude.<$> Maybe [AttributeValue]
attributeValueList,
            (Key
"ComparisonOperator" forall kv v. (KeyValue kv, ToJSON v) => Key -> v -> kv
Data..=)
              forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
Prelude.<$> Maybe ComparisonOperator
comparisonOperator,
            (Key
"Exists" forall kv v. (KeyValue kv, ToJSON v) => Key -> v -> kv
Data..=) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
Prelude.<$> Maybe Bool
exists,
            (Key
"Value" forall kv v. (KeyValue kv, ToJSON v) => Key -> v -> kv
Data..=) forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
Prelude.<$> Maybe AttributeValue
value
          ]
      )