[FormBuilder] What to do with `formConfig` then building the form dynamically ?

[MangelMaxime]

Issue by MangelMaxime
Tuesday Nov 27, 2018 at 12:47 GMT
Originally opened as MangelMaxime/Thoth#88

---

The documentation explain this scenario:

let (formState, formConfig) =
    Form<Msg>
        .Create(OnFormMsg)
        .AddField(
            BasicInput
                .Create("firstname")
                .WithDefaultView()
        )
        .Build()

So caching formConfig is possible directly.

But if you have something like:

let createForm (userInfo : UserInfo) =
    Form<Msg>
        .Create(OnFormMsg)
        .AddField(
            BasicInput
                .Create("firstname")
                .WithValue(userInfo.Firstname)
                .WithDefaultView()
        )
        .Build()

Then you formConfig isn't cached by default. Current solution is to use a mutable variable to store the formConfig:

let mutable formConfig = Unchecked.defaultof<Types.Config<Msg>>

// Then to init the form
            let (state, config) =
                createForm currentUser userInfo

            formConfig <- config

            let (formState, formCmd) =
                Form.init formConfig state

Which isn't perfect. We should make formConfig cached by default and probably handle by the library in a special spaces.

One thing to take care is to destroy an old formConfig that is not useful anymore.