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1. getEntityIdField :: EntityDef -> Maybe FieldDef

   persistent	Database.Persist.EntityDef

   No documentation available.

2. setEntityId :: FieldDef -> EntityDef -> EntityDef

   persistent	Database.Persist.EntityDef

   Set an entityId to be the given FieldDef.

3. setEntityIdDef :: EntityIdDef -> EntityDef -> EntityDef

   persistent	Database.Persist.EntityDef

   No documentation available.

4. data EntityIdDef

   persistent	Database.Persist.EntityDef.Internal

   The definition for the entity's primary key ID.

5. EntityIdField :: FieldDef -> EntityIdDef

   persistent	Database.Persist.EntityDef.Internal

   The entity has a single key column, and it is a surrogate key - that is, you can't go from rec -> Key rec.

6. EntityIdNaturalKey :: CompositeDef -> EntityIdDef

   persistent	Database.Persist.EntityDef.Internal

   The entity has a natural key. This means you can write rec -> Key rec because all the key fields are present on the datatype. A natural key can have one or more columns.

7. entityId :: EntityDef -> !EntityIdDef

   persistent	Database.Persist.EntityDef.Internal

   The entity's primary key or identifier.

8. fieldIsImplicitIdColumn :: FieldDef -> !Bool

   persistent	Database.Persist.FieldDef.Internal

   True if the field is an implicit ID column. False otherwise.

9. module Database.Persist.ImplicitIdDef

   This module contains types and functions for creating an ImplicitIdDef, which allows you to customize the implied ID column that persistent generates. If this module doesn't suit your needs, you may want to import Database.Persist.ImplicitIdDef.Internal instead. If you do so, please file an issue on GitHub so we can support your needs. Breaking changes to that module will *not* be accompanied with a major version bump.

10. data ImplicitIdDef

    persistent	Database.Persist.ImplicitIdDef

    A specification for how the implied ID columns are created. By default, persistent will give each table a default column named id (customizable by PersistSettings), and the column type will be whatever you'd expect from BackendKey yourBackendType. For The SqlBackend type, this is an auto incrementing integer primary key. You might want to give a different example. A common use case in postgresql is to use the UUID type, and automatically generate them using a SQL function. Previously, you'd need to add a custom Id annotation for each model.

    User
    Id   UUID default="uuid_generate_v1mc()"
    name Text
    
    Dog
    Id   UUID default="uuid_generate_v1mc()"
    name Text
    user UserId
    

    Now, you can simply create an ImplicitIdDef that corresponds to this declaration.

    newtype UUID = UUID ByteString
    
    instance PersistField UUID where
    toPersistValue (UUID bs) =
    PersistLiteral_ Escaped bs
    fromPersistValue pv =
    case pv of
    PersistLiteral_ Escaped bs ->
    Right (UUID bs)
    _ ->
    Left "nope"
    
    instance PersistFieldSql UUID where
    sqlType _ = SqlOther UUID
    

    With this instance at the ready, we can now create our implicit definition:

    uuidDef :: ImplicitIdDef
    uuidDef = mkImplicitIdDef @UUID "uuid_generate_v1mc()"
    

    And we can use setImplicitIdDef to use this with the MkPersistSettings for our block.

    mkPersist (setImplicitIdDef uuidDef sqlSettings) [persistLowerCase| ... |]
    

    TODO: either explain interaction with mkMigrate or fix it. see issue #1249 for more details.

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