Database.PostgreSQL.Entity.Internal

Internal helpers used to implement the high-level API and SQL combinators.

You can re-use those building blocks freely to create your own wrappers.

Helpers

isNotNull :: Vector Field -> Text

Produce an IS NOT NULL statement given a vector of fields

>>> isNotNull [ [field| possibly_empty |] ]
"\"possibly_empty\" IS NOT NULL"

>>> isNotNull [[field| possibly_empty |], [field| that_one_too |]]
"\"possibly_empty\" IS NOT NULL AND \"that_one_too\" IS NOT NULL"

Since: 0.0.1.0

isNull :: Vector Field -> Text

Produce an IS NULL statement given a vector of fields

>>> isNull [ [field| possibly_empty |] ]
"\"possibly_empty\" IS NULL"

>>> isNull [[field| possibly_empty |], [field| that_one_too |]]
"\"possibly_empty\" IS NULL AND \"that_one_too\" IS NULL"

Since: 0.0.1.0

inParens :: Text -> Text

Wrap the given text between parentheses

Examples

>>> inParens "wrap me!"
"(wrap me!)"

Since: 0.0.1.0

quoteName :: Text -> Text

Wrap the given text between double quotes

Examples

>>> quoteName "meow."
"\"meow.\""

Since: 0.0.1.0

getTableName :: forall e. Entity e => Text

Safe getter that quotes a table name

Examples

>>> getTableName @Author
"\"authors\""

expandFields :: forall e. Entity e => Text

Produce a comma-separated list of an entity's fields.

Examples

>>> expandFields @BlogPost
"\"blogpost_id\", \"author_id\", \"uuid_list\", \"title\", \"content\", \"created_at\""

Since: 0.0.1.0

expandQualifiedFields :: forall e. Entity e => Text

Produce a comma-separated list of an entity's fields, qualified with the table name

Examples

>>> expandQualifiedFields @BlogPost
"blogposts.\"blogpost_id\", blogposts.\"author_id\", blogposts.\"uuid_list\", blogposts.\"title\", blogposts.\"content\", blogposts.\"created_at\""

Since: 0.0.1.0

expandQualifiedFields' :: Vector Field -> Text -> Text

Produce a comma-separated list of an entity's fields, qualified with an arbitrary prefix

Examples

>>> expandQualifiedFields' (fields @BlogPost) "legacy"
"legacy.\"blogpost_id\", legacy.\"author_id\", legacy.\"uuid_list\", legacy.\"title\", legacy.\"content\", legacy.\"created_at\""

Since: 0.0.1.0

qualifyFields :: Text -> Vector Field -> Vector Field

Take a prefix and a vector of fields, and qualifies each field with the prefix

Examples

>>> qualifyFields "legacy" (fields @BlogPost)
[Field "legacy.\"blogpost_id\"" Nothing,Field "legacy.\"author_id\"" Nothing,Field "legacy.\"uuid_list\"" (Just "uuid[]"),Field "legacy.\"title\"" Nothing,Field "legacy.\"content\"" Nothing,Field "legacy.\"created_at\"" Nothing]

Since: 0.0.1.0

placeholder :: Field -> Text

Produce a placeholder of the form "field" = ? with an optional type annotation.

Examples

>>> placeholder [field| id |]
"\"id\" = ?"

>>> placeholder $ [field| ids :: uuid[] |]
"\"ids\" = ?::uuid[]"

>>> fmap placeholder $ fields @BlogPost
["\"blogpost_id\" = ?","\"author_id\" = ?","\"uuid_list\" = ?::uuid[]","\"title\" = ?","\"content\" = ?","\"created_at\" = ?"]

Since: 0.0.1.0

generatePlaceholders :: Vector Field -> Text

Generate an appropriate number of “?” placeholders given a vector of fields.

Used to generate INSERT queries.

Examples

>>> generatePlaceholders $ fields @BlogPost
"?, ?, ?::uuid[], ?, ?, ?"

Since: 0.0.1.0

textToQuery :: Text -> Query

Since the Query type has an IsString instance, the process of converting from Text to String to Query is factored into this function

⚠ This may be dangerous and an unregulated usage of this function may expose to you SQL injection attacks @since 0.0.1.0

queryToText :: Query -> Text

For cases where combinator composition is tricky, we can safely get back to a Text string from a Query

⚠ This may be dangerous and an unregulated usage of this function may expose to you SQL injection attacks @since 0.0.1.0

intercalateVector :: Text -> Vector Text -> Vector Text

The intercalateVector function takes a Text and a Vector Text and concatenates the vector after interspersing the first argument between each element of the list.

Examples

>>> intercalateVector "~" []
[]

>>> intercalateVector "~" ["nyan"]
["nyan"]

>>> intercalateVector "~" ["nyan", "nyan", "nyan"]
["nyan","~","nyan","~","nyan"]

Since: 0.0.1.0