tilmans / elm-firebase

Firebase bindings for Elm

WARNING

The current state of this is very limited, and this is very much in alpha. Consider the API in flux.

It is completely possible that master will be broken at any given time until we hit a stable 1.x.

elm-firebase

elm-firebase is a set of bindings between Elm >= 0.18 and Firebase 3.x.

Goals

• Be as close to the javascript api as possible.
• Follow the elm architecture.

Getting started

First, you'll need to install elm-github-install.

$ npm install elm-github-install -g

Then you can add elm-firebase to your elm-package.json like so:

{
  "dependencies": {
    "pairshaped/elm-firebase": "0.0.5 <= v < 1.0.0"
  },
  "dependency-sources": {
    "pairshaped/elm-firebase": {
      "url": "https://github.com/pairshaped/elm-firebase.git",
      "ref": "master"
    }
  }
}

Now you're ready to install!

$ elm-github-install

Connecting to your firebase database

import Html
import Firebase
import Firebase.Database.Types
import Firebase.Database.Reference
import Firebase.Database.Snapshot



main =
  Html.program
      { init = init
      , update = update
      , subscriptions = \_ -> Sub.none
      , view = -- ...
      }

type alias Model =
    { app : Firebase.App
    , db : Firebase.Database.Types.Database
    }


init : ( Model, Cmd Msg )
init =
  let
      app : Firebase.App
      app =
          Firebase.init
              { apiKey: "your firebase api key"
              , databaseURL: "https://your-firebase-app.firebaseio.com"
              , -- These are necessary for just connecting to your database
                authDomain: ""
              , storageBucket: ""
              , messagingSenderId: ""
              }

      {-
          It's not necessary to store the database, but it will make it easier
          since all your database interactions are going to either be in `update`
          or `subscriptions`, and both have access to your model.
      -}
      db : Firebase.Database.Types.Database
      db =
          Firebase.Database.init app

      initialModel : Model
      initialModel =
          { app = app
          , db = db
          }
  in
      ( initialModel
      , Cmd.none
      )

Getting the value of a reference

import Firebase
import Firebase.Database.Types
import Firebase.Database.Reference
import Firebase.Database.Snapshot



-- Same main/model/init stuff as above...


type Msg
    = GetValueOfFoo
    | FooValue Firebase.Database.Types.Snapshot


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    GetValueOfFoo ->
        let
            fooRef : Firebase.Database.Types.Reference
            fooRef =
                model.db
                    |> Firebase.Database.ref (Just "foo")
        in
            ( model
            , Task.perform FooValue (Firebase.Database.Reference.once "value" fooRef)
            )

    FooValue snapshot ->
        let
            {-
              This decodes the value of "/foo" as a string.
            -}
            value : Result String String
            value =
                snapshot
                    |> Firebase.Database.Snapshot.value           -- Gives us a Json.Decode.Value
                    |> Json.Decode.decodeValue Json.Decode.string -- Convert into a Result String a (where a is a String)
                    |> Debug.log "FooValue.value.result"          -- Output the result (either `Err decodeMessage` or `Ok value`)
        in
            ( model
            , Cmd.none
            )

Subscribing to changes of a reference

import Firebase
import Firebase.Database.Types
import Firebase.Database.Reference
import Firebase.Database.Snapshot



main =
  Html.program
      { init = init
      , update = update
      , subscriptions = subscriptions
      , view = -- ...
      }



-- Same model/init as above...


type Msg
    = FooValue Firebase.Database.Types.Snapshot


update : Msg -> Model -> ( Model, Cmd Msg )
update msg model =
    FooValue snapshot ->
        let
            {-
              This decodes the value of "/foo" as a string.
            -}
            value : Result String String
            value =
                snapshot
                    |> Firebase.Database.Snapshot.value           -- Gives us a Json.Decode.Value
                    |> Json.Decode.decodeValue Json.Decode.string -- Convert into a Result String a (where a is a String)
                    |> Debug.log "FooValue.value.result"          -- Output the result (either `Err decodeMessage` or `Ok value`)
        in
            ( model
            , Cmd.none
            )


subscriptions : Model -> Sub Msg
subscriptions model =
    let
        fooRef : Firebase.Database.Types.Reference
        fooRef =
            model.db
                |> Firebase.Database.ref (Just "foo")
    in
      Sub.batch
          [ Firebase.Database.Reference.on "value" fooRef FooValue
          ]

Example

Check out the kitchen sink or writer examples for information.

Alternatives

• elmfire