reactjs - 如何在 Fable 中实例化自定义 React 组件？

Question

我正在尝试使用 Fable 编写一个简单的 React 组件。它应该显示一个带有 + 的简单计数器和 -纽扣。也需要留言string通过 Prop 。
出乎意料的是代码可以编译，但会引发运行时错误:

Error: Objects are not valid as a React child (found: object with keys {props, context, refs, updater, state}).

If you meant to render a collection of children, use an array instead.

这是代码:

module App

open Fable.Core
open Fable.Core.JsInterop
open Fable.React
open Browser
open Browser.Types

type App (message) =
  inherit Component<string, int> (message) with

    do
      base.setInitState(0)

    override this.render () =
      div
        []
        [
          h1 [] [ str (sprintf "%s - %i" this.props this.state) ]
          button [ Props.OnClick (fun _ -> this.setState (fun s _ -> s + 1)) ] [ str "+" ]
          button [ Props.OnClick (fun _ -> this.setState (fun s _ -> s - 1)) ] [ str "-" ]
        ]


let render () =
  ReactDom.render(
    App "Counter",
    document.getElementById "root")

render ()

我的 paket.lock :

STORAGE: NONE
RESTRICTION: || (== netcoreapp3.1) (== netstandard2.0) (== netstandard2.1)
NUGET
  remote: https://api.nuget.org/v3/index.json
    Fable.Browser.Blob (1.1)
      Fable.Core (>= 3.0)
      FSharp.Core (>= 4.6.2)
    Fable.Browser.Dom (1.1)
      Fable.Browser.Blob (>= 1.1)
      Fable.Browser.Event (>= 1.0)
      Fable.Browser.WebStorage (>= 1.0)
      Fable.Core (>= 3.0)
      FSharp.Core (>= 4.6.2)
    Fable.Browser.Event (1.0)
      Fable.Core (>= 3.0)
      FSharp.Core (>= 4.5.2)
    Fable.Browser.WebStorage (1.0)
      Fable.Browser.Event (>= 1.0)
      Fable.Core (>= 3.0)
      FSharp.Core (>= 4.5.2)
    Fable.Core (3.1.5)
      FSharp.Core (>= 4.7)
    Fable.React (5.3.6)
      Fable.Browser.Dom (>= 1.0)
      Fable.Core (>= 3.0)
      FSharp.Core (>= 4.7)
    FSharp.Core (4.7)

注意:我想使用 setState (而不是钩子(Hook)或 Elmish)出于各种原因。

Answer 1

在您的 render功能，需要使用ofType像这样:

let render () =
  ReactDom.render(
    ofType<App,_,_> "Counter" [],
    document.getElementById "root")

这会渲染一些东西，但是当你点击按钮时什么也没有发生。
要解决此问题，请从 int 更改您的状态到 object :

type state = { count: int }
//..
button [ Props.OnClick (fun _ -> this.setState (fun s _ -> { s with count = s.count + 1 })) ] [ str "+" ]

最后，将您的 Prop 更改为 object .
总而言之，以下应该有效:

type props = { message: string }
type state = { count: int }

type App (props) =
  inherit Component<props, state> (props) with

    do
      base.setInitState({ count = 0 })

    override this.render () =
      div
        []
        [
          h1 [] [ str (sprintf "%s - %i" this.props.message this.state.count) ]
          button [ Props.OnClick (fun _ -> this.setState (fun s _ -> { s with count = s.count + 1 })) ] [ str "+" ]
          button [ Props.OnClick (fun _ -> this.setState (fun s _ -> { s with count = s.count - 1 })) ] [ str "-" ]
        ]


let render () =
  ReactDom.render(
    ofType<App,_,_> { message = "Counter" } [],
    document.getElementById "root")

render ()

您可以包装 ofType调用一个方便的函数:

let inline app props children = 
  ofType<App,_,_> props children

let render () =
  ReactDom.render(
    app { message = "Counter" } [],
    document.getElementById "root")
    
render ()