postgresql-orm-0.3.0: An ORM (Object Relational Mapping) and migrations DSL for PostgreSQL.

Safe HaskellNone

Database.PostgreSQL.Migrations

Contents

Description

Functions to help with building database migrations.

Most users will want to create a database migration using defaultMain as follows,

 import Database.PostgreSQL.Migrations

 main = defaultMain up down

 up = migrate $ do
       create_table "posts"
         [ column "title" "VARCHAR(255) NOT NULL"
         , column "author_id" "integer references authors(id)"]
 
 down = migrate $ drop_table "posts"

Synopsis

Utilities

defaultMainSource

Arguments

:: (Connection -> IO ())

Migration function

-> (Connection -> IO ())

Rollback function

-> IO () 

connectEnv :: IO ConnectionSource

Creates a PostgreSQL Connection using the DATABASE_URL environment variable, if it exists. If it does, it should match the format:

   postgresql://[[USERNAME@PASSWORD]HOSTNAME[:PORT]]/[DBNAME]

If it is not present, the environment variables PG_DBNAME PG_HOST etc, are used.

runSqlFile :: FilePath -> Migration ()Source

Runs the SQL file at the given path, relative to the current working directory.

DSL

columnSource

Arguments

:: ByteString

name

-> ByteString

type, definition, constraints

-> ByteString 

Returns a column defition by quoting the given name

Adding

create_tableSource

Arguments

:: ByteString

Table name

-> [ByteString]

Column definitions

-> Migration Int64 

Creates a table. See column for constructing the column list.

add_columnSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> ByteString

Column definition

-> Migration Int64 

Adds a column to the given table. For example,

   add_column "posts" "title" "VARCHAR(255)"

adds a varchar column called "title" to the table "posts".

create_indexSource

Arguments

:: ByteString

Index name

-> ByteString

Table name

-> [ByteString]

Column names

-> Migration Int64 

Creates an index for efficient lookup.

create_unique_indexSource

Arguments

:: ByteString

Index name

-> ByteString

Table name

-> [ByteString]

Column names

-> Migration Int64 

Creates a unique index for efficient lookup.

Removing

drop_columnSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> Migration Int64 

Drops a column from the given table. For example,

   drop_column "posts" "title"

drops the column "title" from the "posts" table.

drop_indexSource

Arguments

:: ByteString

Index name

-> Migration Int64 

Drops an index.

Modifying

rename_columnSource

Arguments

:: ByteString

Table name

-> ByteString

Old column name

-> ByteString

New column name

-> Migration Int64 

Renames a column in the given table. For example,

   rename_column "posts" "title" "name"

renames the column "title" in the "posts" table to "name".

change_columnSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> ByteString

Action

-> Migration Int64 

Alters a column in the given table. For example,

   change_column "posts" "title" "DROP DEFAULT"

drops the default constraint for the "title" column in the "posts" table.

Statements

create_table_stmtSource

Arguments

:: ByteString

Table name

-> [ByteString]

Column definitions

-> Query 

Returns a Query that creates a table, for example:

   create_table "posts"
     [ column "title" "VARCHAR(255) NOT NULL"
     , column "body"  "text"]

add_column_stmtSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> ByteString

Column definition

-> Query 

Returns a Query that adds a column to the given table. For example,

   add_column "posts" "title" "VARCHAR(255)"

Returns the query

   ALTER TABLE "posts" add "title" VARCHAR(255);

create_index_stmtSource

Arguments

:: Bool

Unique index?

-> ByteString

Index name

-> ByteString

Table name

-> [ByteString]

Column names

-> Query 

Returns a Query that creates an index for the given columns on the given table. For example,

   create_index_stmt "post_owner_index" "posts" "owner"

Returns the query

   CREATE INDEX "post_owner_index" ON "posts" ("owner")

drop_table_stmt :: ByteString -> QuerySource

Returns a Query that drops a table

drop_column_stmtSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> Query 

Returns a Query that drops a column from the given table. For example,

   drop_column "posts" "title"

Returns the query

   ALTER TABLE "posts" add "title";

drop_index_stmtSource

Arguments

:: ByteString

Index name

-> Query 

Returns a Query that drops an index.

   drop_index_stmt "post_owner_index"

Returns the query

   DROP INDEX "post_owner_index"

rename_column_stmtSource

Arguments

:: ByteString

Table name

-> ByteString

Old column name

-> ByteString

New column name

-> Query 

Returns a Query that renames a column in the given table. For example,

   rename_column "posts" "title" "name"

Returns the query

   ALTER TABLE "posts" RENAME "title" TO "name";

change_column_stmtSource

Arguments

:: ByteString

Table name

-> ByteString

Column name

-> ByteString

Action

-> Query 

Returns a Query that alters a column in the given table. For example,

   change_column "posts" "title" "DROP DEFAULT"

Returns the query

   ALTER TABLE "posts" ALTER "title" DROP DEFAULT;