Using HashDB In a Scaffolded Site

Sibi Prabakaran edited this page Jun 22, 2016 · 9 revisions
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[WARNING] Yesod Cookbook has moved to a new place. Please contribute there.

Example with Yesod Scaffold and Your Own Model:

  1. Your object representing clients must provide a unique identifier field, a field for the password hash, and a field for the password salt. Example:

    -- in config/models
        email    Text
        password Text
        UniqueEmail email
        deriving Typeable

    In this example, 'email' will be the unique identifier.

  2. You must provide

    instance HashDBUser (<yourObject>Generic backend)

    in the module that shares your model. In the scaffolded site, that module is Model. Continuing the Person example,

    -- in Model.hs
    import Yesod.Auth.HashDB (HashDBUser(..))
    instance HashDBUser Person where
        userPasswordHash = Just . personPassword
        setPasswordHash h p = p { personPassword = h }
  3. Now, in Foundation.hs, we hook Auth.HashDB into your foundation. You must add an import of Yesod.Auth.HashDB, of course,

    import Yesod.Auth.HashDB (authHashDB, getAuthIdHashDB)

    and then modify the YesodAuth instance like so:

    -- in Foundation.hs
    instance YesodAuth <MySite> where
        type AuthId <MySite> = PersonId
        -- ... loginDest, etc.
        getAuthId creds = getAuthIdHashDB AuthR (Just . UniqueEmail) creds
        authPlugins _ = [authHashDB (Just . UniqueEmail)]

Further examples can be found in the module documentation