How to perform database queries in GHCi in Yesod Application

ghci, haskell, persistent, yesod

Solution

If you just want to do Persistent queries in ghci you can do this without creating a Yesod application. Unfortunately doing this is differs quite a bit depending on the specific back end you want to use.

For SQLite:

> import Database.Persist.Sqlite
> import Model
> pool <- createSqlitePool "yesod-test.sqlite3" 2
> runSqlite "yesod-test.sqlite3" (runMigration migrateAll)
> userId <- runSqlite "yesod-test.sqlite3" (insert (User "foo@bar.com" Nothing))

For Postgresql:

-- In Shell: $ createdb yesod-test
> import Database.PostgreSQL.Simple
> con <- connectPostgreSQL  "dbname=yesod-test"
> import Database.Persist.Postgresql
> pcon <- openSimpleConn con
> import Model
> runSqlPersistM (runMigration migrateAll) pcon
> userId <- runSqlPersistM (insert (User "foo@bar.com" Nothing)) pcon
> Just user <- runSqlPersistM (get userId) pcon
> userIdent user

Problem

How to, for example, insert a new User into a database using Yesod application's models? Or is there a better way? I am dealing with scaffolded application. Now I created `App` instance and dont know how to perform requests using it. ``` :i Extra data Extra = Extra {extraCopyright :: Data.Text.Internal.Text, extraAnalytics :: Maybe Data.Text.Internal.Text} -- Defined in `Settings let e = Extra "asdf" Nothing let c = AppConfig {appEnv = Development, appPort = 3000, appRoot = "/", appHost = "localhost", appExtra = e} f <- makeFoundation c :t f f :: App :i App data App = App {settings :: AppConfig DefaultEnv Extra, getStatic :: Yesod.Static.Static, connPool :: persistent-1.2.3.0:Database.Persist.Class.PersistConfig.PersistConfigPool PersistConf, httpManager :: http-client-0.2.0.1:Network.HTTP.Client.Types.Manager, persistConfig :: PersistConf, appLogger :: Yesod.Core.Types.Logger} -- Defined in `Foundation' ``` What next?

Original source