Database.Persist.MongoDB

Use persistent-mongodb the same way you would use other persistent libraries and refer to the general persistent documentation. There are some new MongoDB specific filters under the filters section. These help extend your query into a nested document.

However, at some point you will find the normal Persistent APIs lacking. and want lower level-level MongoDB access. There are functions available to make working with the raw driver easier: they are under the Entity conversion section. You should still use the same connection pool that you are using for Persistent.

MongoDB is a schema-less database. The MongoDB Persistent backend does not help perform migrations. Unlike SQL backends, uniqueness constraints cannot be created for you. You must place a unique index on unique fields.

Entity conversion

collectionName :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => record -> Text

docToEntityEither :: forall record. PersistEntity record => Document -> Either Text (Entity record)

docToEntityThrow :: forall m record. (MonadIO m, PersistEntity record, PersistEntityBackend record ~ MongoContext) => Document -> m (Entity record)

entityToDocument :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => record -> Document

Deprecated: use recordToDocument

recordToDocument :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => record -> Document

convert a PersistEntity into document fields. unlike toInsertDoc, nulls are included.

documentFromEntity :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => Entity record -> Document

toInsertDoc :: forall record. (PersistEntity record, PersistEntityBackend record ~ MongoContext) => record -> Document

convert a PersistEntity into document fields. for inserts only: nulls are ignored so they will be unset in the document. entityToDocument includes nulls

entityToInsertDoc :: forall record. (PersistEntity record, PersistEntityBackend record ~ MongoContext) => Entity record -> Document

updatesToDoc :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => [Update record] -> Document

filtersToDoc :: (PersistEntity record, PersistEntityBackend record ~ MongoContext) => [Filter record] -> Document

toUniquesDoc :: forall record. PersistEntity record => Unique record -> [Field]

convert a unique key into a MongoDB document

MongoDB specific queries

(->.) :: forall record emb typ. PersistEntity emb => EntityField record [emb] -> EntityField emb typ -> NestedField record typ infixr 6

Point to an array field with an embedded object and give a deeper query into the embedded object. Use with nestEq.

(~>.) :: forall record typ emb. PersistEntity emb => EntityField record [emb] -> NestedField emb typ -> NestedField record typ infixr 5

Point to an array field with an embedded object and give a deeper query into the embedded object. This level of nesting is not the final level. Use ->. or &->. to point to the final level.

(?&->.) :: forall record typ nest. PersistEntity nest => EntityField record (Maybe nest) -> EntityField nest typ -> NestedField record typ infixr 6

Same as &->., but Works against a Maybe type

(?&~>.) :: forall val nes nes1. PersistEntity nes1 => EntityField val (Maybe nes1) -> NestedField nes1 nes -> NestedField val nes infixr 5

Same as &~>., but works against a Maybe type

(&->.) :: forall record typ nest. PersistEntity nest => EntityField record nest -> EntityField nest typ -> NestedField record typ infixr 6

Point to a nested field to query. This field is not an array type. Use with nestEq.

(&~>.) :: forall val nes nes1. PersistEntity nes1 => EntityField val nes1 -> NestedField nes1 nes -> NestedField val nes infixr 5

Point to a nested field to query. This field is not an array type. This level of nesting is not the final level. Use ->. or &>. to point to the final level.

Filters

You can find example usage for all of Persistent in our test cases: https://github.com/yesodweb/persistent/blob/master/persistent-test/EmbedTest.hs#L144

These filters create a query that reaches deeper into a document with nested fields.

nestEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

nestNe :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

nestGe :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

nestLe :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

nestIn :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

nestNotIn :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Filter record infixr 4

The normal Persistent equality test ==. is not generic enough. Instead use this with the drill-down arrow operaters such as ->.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({"object.field": item})

anyEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> typ -> Filter record infixr 4

Like '(==.)' but for an embedded list. Checks to see if the list contains an item.

In Haskell we need different equality functions for embedded fields that are lists or non-lists to keep things type-safe.

using this as the only query filter is similar to the following in the mongoDB shell

db.Collection.find({arrayField: arrayItem})

nestAnyEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record [typ] -> typ -> Filter record infixr 4

Like nestEq, but for an embedded list. Checks to see if the nested list contains an item.

nestBsonEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> Value -> Filter record infixr 4

same as nestEq, but give a BSON Value

anyBsonEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> Value -> Filter record infixr 4

same as anyEq, but give a BSON Value

multiBsonEq :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> Value -> Filter record infixr 4

Deprecated: Please use anyBsonEq instead

(=~.) :: forall record searchable. (MongoRegexSearchable searchable, PersistEntity record, PersistEntityBackend record ~ MongoContext) => EntityField record searchable -> MongoRegex -> Filter record infixr 4

Filter using a Regular expression.

data NestedField record typ

Constructors

forall emb . PersistEntity emb => (EntityField record [emb]) `LastEmbFld` (EntityField emb typ)

forall emb . PersistEntity emb => (EntityField record [emb]) `MidEmbFld` (NestedField emb typ)

forall nest . PersistEntity nest => (EntityField record nest) `MidNestFlds` (NestedField nest typ)

forall nest . PersistEntity nest => (EntityField record (Maybe nest)) `MidNestFldsNullable` (NestedField nest typ)

forall nest . PersistEntity nest => (EntityField record nest) `LastNestFld` (EntityField nest typ)

forall nest . PersistEntity nest => (EntityField record (Maybe nest)) `LastNestFldNullable` (EntityField nest typ)

class PersistField typ => MongoRegexSearchable typ

Mark the subset of PersistFields that can be searched by a mongoDB regex Anything stored as PersistText or an array of PersistText would be valid

Instances

MongoRegexSearchable Text

MongoRegexSearchable rs => MongoRegexSearchable [rs]

MongoRegexSearchable rs => MongoRegexSearchable (Maybe rs)

type MongoRegex = (Text, Text)

A MongoRegex represents a Regular expression. It is a tuple of the expression and the options for the regular expression, respectively Options are listed here: http://docs.mongodb.org/manual/reference/operator/query/regex/ If you use the same options you may want to define a helper such as r t = (t, "ims")

Updates

nestSet :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Update record infixr 4

nestInc :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Update record

nestDec :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Update record

nestMul :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => NestedField record typ -> typ -> Update record

push :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> typ -> Update record infixr 4

pull :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> typ -> Update record infixr 4

pullAll :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> [typ] -> Update record infixr 4

addToSet :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => EntityField record [typ] -> typ -> Update record infixr 4

eachOp :: forall record typ. (PersistField typ, PersistEntityBackend record ~ MongoContext) => (EntityField record [typ] -> typ -> Update record) -> EntityField record [typ] -> [typ] -> Update record

equivalent to $each

eachOp push field []

eachOp pull will get translated to $pullAll

Key conversion helpers

data family BackendKey backend

Instances

Bounded (BackendKey SqlBackend)

Enum (BackendKey SqlBackend)

Eq (BackendKey MongoContext)

Eq (BackendKey SqlBackend)

Integral (BackendKey SqlBackend)

Num (BackendKey SqlBackend)

Ord (BackendKey MongoContext)

Ord (BackendKey SqlBackend)

Read (BackendKey MongoContext)

Read (BackendKey SqlBackend)

Real (BackendKey SqlBackend)

Show (BackendKey MongoContext)

Show (BackendKey SqlBackend)

ToJSON (BackendKey MongoContext)

It would make sense to define the instance for ObjectId and then use newtype deriving however, that would create an orphan instance

ToJSON (BackendKey SqlBackend)

FromJSON (BackendKey MongoContext)

FromJSON (BackendKey SqlBackend)

PathPiece (BackendKey MongoContext)

ToPathPiece is used to convert a key to/from text

PathPiece (BackendKey SqlBackend)

PersistFieldSql (BackendKey MongoContext)

PersistFieldSql (BackendKey SqlBackend)

PersistField (BackendKey MongoContext)

PersistField (BackendKey SqlBackend)

data BackendKey MongoContext = MongoKey {

• unMongoKey :: ObjectId

}

data BackendKey SqlBackend = SqlBackendKey {

• unSqlBackendKey :: Int64

}

keyToOid :: ToBackendKey MongoContext record => Key record -> ObjectId

oidToKey :: ToBackendKey MongoContext record => ObjectId -> Key record

recordTypeFromKey :: Key record -> record

readMayObjectId :: Text -> Maybe ObjectId

readMayMongoKey :: Text -> Maybe (BackendKey MongoContext)

Convert a Text to a Key

keyToText :: BackendKey MongoContext -> Text

PersistField conversion

fieldName :: forall record typ. PersistEntity record => EntityField record typ -> Label

using connections

withConnection :: (MonadIO m, Applicative m) => MongoConf -> (ConnectionPool -> m b) -> m b

withMongoPool :: (MonadIO m, Applicative m) => MongoConf -> (ConnectionPool -> m b) -> m b

withMongoDBConn :: (MonadIO m, Applicative m) => Database -> HostName -> PortID -> Maybe MongoAuth -> NominalDiffTime -> (ConnectionPool -> m b) -> m b

withMongoDBPool :: (MonadIO m, Applicative m) => Database -> HostName -> PortID -> Maybe MongoAuth -> Int -> Int -> NominalDiffTime -> (ConnectionPool -> m b) -> m b

createMongoDBPool

Arguments

:: (MonadIO m, Applicative m)

=> Database

-> HostName

-> PortID

-> Maybe MongoAuth

-> Int

pool size (number of stripes)

-> Int

stripe size (number of connections per stripe)

-> NominalDiffTime

time a connection is left idle before closing

-> m ConnectionPool

runMongoDBPool :: (MonadIO m, MonadBaseControl IO m) => AccessMode -> Action m a -> ConnectionPool -> m a

runMongoDBPoolDef :: (MonadIO m, MonadBaseControl IO m) => Action m a -> ConnectionPool -> m a

use default AccessMode

type ConnectionPool = Pool Connection

data Connection

data MongoAuth

Constructors

MongoAuth Username Password

Instances

Show MongoAuth

Connection configuration

data MongoConf

Information required to connect to a mongo database

Constructors

MongoConf

Fields

mgDatabase :: Text

mgHost :: Text

mgPort :: PortID

mgAuth :: Maybe MongoAuth

mgAccessMode :: AccessMode

mgPoolStripes :: Int

mgStripeConnections :: Int

mgConnectionIdleTime :: NominalDiffTime

mgReplicaSetConfig :: Maybe ReplicaSetConfig

YAML fields for this are rsName and rsSecondaries mgHost is assumed to be the primary

Instances

Show MongoConf

FromJSON MongoConf

PersistConfig MongoConf

type PersistConfigPool MongoConf = ConnectionPool

type PersistConfigBackend MongoConf = Action

defaultMongoConf :: Text -> MongoConf

defaultHost :: Text

defaultAccessMode :: AccessMode

defaultPoolStripes :: Int

defaultConnectionIdleTime :: NominalDiffTime

defaultStripeConnections :: Int

applyDockerEnv :: MongoConf -> IO MongoConf

docker integration: change the host to the mongodb link

using raw MongoDB pipes

type PipePool = Pool Pipe

createMongoDBPipePool

Arguments

:: (MonadIO m, Applicative m)

=> HostName

-> PortID

-> Int

pool size (number of stripes)

-> Int

stripe size (number of connections per stripe)

-> NominalDiffTime

time a connection is left idle before closing

-> m PipePool

A pool of plain MongoDB pipes. The database parameter has not yet been applied yet. This is useful for switching between databases (on the same host and port) Unlike the normal pool, no authentication is available

runMongoDBPipePool :: (MonadIO m, MonadBaseControl IO m) => AccessMode -> Database -> Action m a -> PipePool -> m a

run a pool created with createMongoDBPipePool

network type

type HostName = String

Either a host name e.g., "haskell.org" or a numeric host address string consisting of a dotted decimal IPv4 address or an IPv6 address e.g., "192.168.0.1".

data PortID :: *

Instances

Eq PortID

Ord PortID

Show PortID

MongoDB driver types

type Database = Text

type Action = ReaderT MongoContext

A monad on top of m (which must be a MonadIO) that may access the database and may fail with a DB Failure

data AccessMode :: *

Type of reads and writes to perform

Constructors

ReadStaleOk

Read-only action, reading stale data from a slave is OK.

UnconfirmedWrites

Read-write action, slave not OK, every write is fire & forget.

ConfirmWrites GetLastError

Read-write action, slave not OK, every write is confirmed with getLastError.

Instances

Show AccessMode

master :: AccessMode

Same as ConfirmWrites []

slaveOk :: AccessMode

Same as ReadStaleOk

(=:) :: Val v => Label -> v -> Field infix 0

Field with given label and typed value

data ObjectId :: *

A BSON ObjectID is a 12-byte value consisting of a 4-byte timestamp (seconds since epoch), a 3-byte machine id, a 2-byte process id, and a 3-byte counter. Note that the timestamp and counter fields must be stored big endian unlike the rest of BSON. This is because they are compared byte-by-byte and we want to ensure a mostly increasing order.

Instances

Eq ObjectId

Ord ObjectId

Read ObjectId

Show ObjectId

Val ObjectId

Serialize ObjectId

PersistFieldSql ObjectId

PersistField ObjectId

Typeable * ObjectId

data MongoContext :: *

Values needed when executing a db operation

Instances

HasMongoContext MongoContext

PersistUnique MongoContext

PersistQuery MongoContext

PersistStore MongoContext

older versions versions of haddock (like that on hackage) do not show that this defines BackendKey DB.MongoContext = MongoKey { unMongoKey :: DB.ObjectId }

HasPersistBackend MongoContext MongoContext

Eq (BackendKey MongoContext)

Ord (BackendKey MongoContext)

Read (BackendKey MongoContext)

Show (BackendKey MongoContext)

ToJSON (BackendKey MongoContext)

It would make sense to define the instance for ObjectId and then use newtype deriving however, that would create an orphan instance

FromJSON (BackendKey MongoContext)

PathPiece (BackendKey MongoContext)

ToPathPiece is used to convert a key to/from text

PersistFieldSql (BackendKey MongoContext)

PersistField (BackendKey MongoContext)

data BackendKey MongoContext = MongoKey {

• unMongoKey :: ObjectId

}

type BackendSpecificUpdate MongoContext record

type BackendSpecificFilter MongoContext record

Database.Persist

module Database.Persist