380dd16 · squeal · git.iko.soy

migration docs

380dd16Eitan Chatav9 years ago

squeal-postgresql/src/Squeal/PostgreSQL/Migration.hs+20−4

@@ -8,8 +8,8 @@ Stability: experimental

8This module defines a `Migration` type to safely

9change the schema of your database over time. Let's see an example!

11−>>> :set -XDataKinds -XDeriveGeneric -XOverloadedLabels

11+>>> :set -XDataKinds -XOverloadedLabels

12−>>> :set -XOverloadedStrings -XTypeApplications -XTypeOperators

12+>>> :set -XOverloadedStrings -XFlexibleContexts -XTypeOperators

13>>> :{

14type UsersTable =

15 '[ "pk_users" ::: 'PrimaryKey '["id"] ] :=>

@@ -61,10 +61,26 @@ let

61 }

62:}

64+>>> :{

65+let

66+ numSteps

67+ :: Has "migration" schema MigrationTable

68+ => PQ schema schema IO ()

69+ numSteps = do

70+ result <- runQuery (selectStar (from (table (#migration `As` #m))))

71+ RowNumber num <- ntuples result

72+ liftBase $ print num

73+:}

74+

64>>> let migration = makeUsers :>> makeEmails :>> Done

75>>> let migration = makeUsers :>> makeEmails :>> Done

76+>>> :{

65−>>> withConnection "host=localhost port=5432 dbname=exampledb" (migrateUp migration)

77+withConnection "host=localhost port=5432 dbname=exampledb" $

78+ migrateUp migration

79+ & pqThen numSteps

80+ & pqThen (migrateDown migration)

81+:}

66NOTICE: relation "migration" already exists, skipping

82NOTICE: relation "migration" already exists, skipping

67−>>> withConnection "host=localhost port=5432 dbname=exampledb" (migrateDown migration)

83+Row 2

68NOTICE: relation "migration" already exists, skipping

84NOTICE: relation "migration" already exists, skipping

69-}

85-}