Elm ORM

A code generator that creates type-safe Elm queries and migrations from your Elm schema definition.

Installation

# Install globally
bun add -g @janwirth/elm-orm

# Or use directly with bun x
bun x @janwirth/elm-orm src/Schema.elm

Usage

# Basic usage
elm-orm src/Schema.elm

# Specify output directory
elm-orm src/Schema.elm --output-dir ./src/Generated

# Get help
elm-orm --help

Example

1. Create a schema file (e.g., src/Schema.elm):

module Schema exposing (..)


-- User-defined types
type alias User =
    { name : String
    , age: Int
    }


type alias Todo =
    { description : String
    , completed : Bool
    }

2. Generate the ORM files:

bun x @janwirth/elm-orm src/Schema.elm

3. This will create two files:

   • Generated/Migrations.elm: Contains SQL migration code
   • Generated/Queries.elm: Contains type-safe query builders

4. Import and use the generated files in your Elm application:

port module TestApp exposing (main)

import Browser
import Html exposing (Html, div, text)
import Json.Encode as Encode
import Task
import Time
import Generated.Queries exposing (..)
import Generated.Migrations exposing (..)


-- PORTS
port executeMigration : String -> Cmd msg
port executeQuery : { query : String, params : List Encode.Value } -> Cmd msg


-- INIT
init : () -> ( Model, Cmd Msg )
init _ =
    ( { results = [], testStatus = NotStarted }
    , executeMigration usersCreateTable
    )


-- Later in your update function
update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    case msg of
        -- After migrations are executed
        MigrationsExecuted ->
            ( { model | testStatus = QueriesExecuted }
            , Cmd.batch
                [ executeQuery { query = createUserQuery, params = [] }
                , executeQuery { query = createTodoQuery, params = [] }
                ]
            )

        -- After queries are executed
        QueriesExecuted ->
            ( { model | testStatus = TestsCompleted }
            , Cmd.batch
                [ executeQuery { query = getAllUsersQuery, params = [] }
                , executeQuery { query = getAllTodosQuery, params = [] }
                ]
            )

Features

• Type-safe query generation
• Automatic migration scripts
• Support for common data types (String, Int, Bool)
• Generated decoders for your types
• Standard CRUD operations

Requirements

• Bun runtime
• Elm compiler

License

MIT