5

我有一个在 aspnet 核心上运行的 react-redux 应用程序，使用 aspnet 预渲染进行服务器端渲染。

假设我犯了一个编程错误，在子组件中我尝试访问一个未定义的道具，因为一个愚蠢的错字。

import {Child} from './child'
export class Parent extends React.Component {
  render () {
    const someProp = {
      something: "something"
    };
    return <Child someProp={someProp} />;
  }
}

export class Child extends React.Component {
  render() {
    return <div>this.props.someprop.something</div>;
         //typo: should be someProp instead of someprop
}

如果没有服务器渲染，我会遇到类似于此的错误：无法在 x:yy 行访问未定义的内容但是使用服务器渲染我得到：

处理请求时发生未处理的异常。

异常：调用节点模块失败并出现错误：预渲染在 30000 毫秒后超时，因为“ClientApp/src/boot-server”中的引导函数返回了一个未解析或拒绝的承诺。确保你的引导函数总是解决或拒绝它的承诺。您可以使用“asp-prerender-timeout”标签助手更改超时值。

这使得调试非常困难，当你没有得到任何关于哪里出错的反馈时。如果出现故障，任何人都知道如何设置拒绝？或者甚至可以调试服务器端呈现的代码？

这是我的引导服务器文件，如果您需要更多文件，请告诉我。 

import * as React from 'react';
import { Provider } from 'react-redux';
import { renderToString } from 'react-dom/server';
import configureStore from './store/configureStore';
import {getFormById} from './actions/getFormActions';
import {updateUserLocale} from './actions/userLocaleActions';
import FormResponder from './components/mainComponents/formResponder';

export default function renderApp (params) {

    return new Promise((resolve, reject) => {

        const store = configureStore();
        store.dispatch(getFormById(params.data.id, params.data.config, params.data.authenticationToken));
        store.dispatch(updateUserLocale(params.data.userLocale));
        const app = (
            <Provider store={ store }>
                <FormResponder />
            </Provider>
        );

    // Perform an initial render that will cause any async tasks (e.g., data access) to begin
    renderToString(app);

    // Once the tasks are done, we can perform the final render
    // We also send the redux store state, so the client can continue execution where the server left off
    params.domainTasks.then(() => {
        resolve({
            html: renderToString(app),
            globals: {
                initialReduxState: store.getState(), 
                authenticationToken: params.data.authenticationToken, 
                config: params.data.config
            }
        });
    }, reject); // Also propagate any errors back into the host application
});
}
4

3 回答 3

5

我在使用 Visual Studio 2017 时也有过类似的经验。我最终意识到原始错误的诊断信息实际上在“输出”窗口中。

于 2017-05-05T18:41:37.673 回答
2

找到了一个适合我的解决方案：我在最终的 renderToString 上插入了一个 try/catch。在哪里捕获我发送一个带有错误的调度。

更新了 boot-server.jsx

params.domainTasks.then(() => {
        let html;
        try {
            html = renderToString(app);
        }
        catch (err) {
            store.dispatch(loadFormFailed( {message: err.toString() } ));
        }

        resolve({
            html: html,
            globals: {
                initialReduxState: store.getState(), 
                authenticationToken: params.data.authenticationToken, 
                config: params.data.config,
                disableReactServerRendring: false
            }
        });
        }, reject);
        // Also propagate any errors back into the host application
    });
于 2016-10-14T13:19:14.150 回答
2

我做了一些研究，得出的结论是暂时无法调试初始服务器呈现的代码。

我所做的是实现逻辑，以便我可以禁用服务器渲染。

这是它的样子：

public async Task<IActionResult> Index(string id, string userLocale = "en", bool server = true)
{ 
    Guid positionId;
    if (!Guid.TryParse(id, out positionId))
    {
        throw new Exception("Invalid position id");        
    }

    var token = await _apiClient.GetToken();

    var formData = new ApplicationFormViewModel()
    {
        Id = positionId,
        UserLocale = userLocale,
        AuthenticationToken = token.AccessToken,
        Server = server
    };
    return View(formData);
}

视图.cshtml：

@{if (@Model.Server) {
    <div 
    class="container"
    id="react-app"
    asp-prerender-module="ClientApp/src/boot-server"
    asp-prerender-data="new {
        Id = @Model.Id, 
        UserLocale = @Model.UserLocale, 
        AuthenticationToken = @Model.AuthenticationToken, 
        Config = new { 
            ApplicationPostUrl = @Url.Action("SaveApplication"),
            AttachmentPostUrl = @Url.Action("UploadAttachment"),
            FormGetUrl = @Url.Action("GetForm")
        }
     }" 
     asp-prerender-webpack-config="webpack.config.js" >
        Loading...
</div>
}
else {
    <script>
        var id= '@Model.Id'; 
        var config= {
            applicationPostUrl: '@Url.Action("SaveApplication")',
            attachmentPostUrl: '@Url.Action("UploadAttachment")',
            formGetUrl: '@Url.Action("GetForm")'
        };
        var userLocale='@Model.UserLocale'; 
        var authenticationToken='@Model.AuthenticationToken'; 
        var server = false;
    </script>
    <div class="container" id="react-app">loading</div>

}
}



@section scripts {

    <script src="~/dist/main.js" asp-append-version="true"></script>
}

引导服务器.jsx：

export default function renderApp (params) {

    return new Promise((resolve, reject) => {

        const store = configureStore();
        store.dispatch(getFormById(params.data.id, params.data.config, params.data.authenticationToken));
        store.dispatch(updateUserLocale(params.data.userLocale));
        const app = (
            <Provider store={ store }>
                <FormResponder />
            </Provider>
        );

    // Perform an initial render that will cause any async tasks (e.g., data access) to begin
    renderToString(app);

    // Once the tasks are done, we can perform the final render
    // We also send the redux store state, so the client can continue execution where the server left off
    params.domainTasks.then(() => {
        resolve({
            html: renderToString(app),
            globals: {
                initialReduxState: store.getState(), 
                authenticationToken: params.data.authenticationToken, 
                config: params.data.config,
                server: true
            }
        });
        }, reject); // Also propagate any errors back into the host application
});
}

引导客户端.jsx：

// Grab the state from a global injected into server-generated HTML
const {id, initialReduxState, authenticationToken, config, server, userLocale } = window;

if (server) {


// Get the application-wide store instance, prepopulating with state from the server where available.
const store = configureStore(initialReduxState);
// This code starts up the React app when it runs in a browser.
ReactDOM.render(
    <Provider store={ store }>
        <FormResponder authenticationToken={authenticationToken} config={config} />
    </Provider>,
    document.getElementById('react-app')
);


}
else {

    const store = configureStore();
    store.dispatch(getFormById(id, config, authenticationToken));
    store.dispatch(updateUserLocale(userLocale));

    render(
        <Provider store ={store}>
            <FormResponder authenticationToken={authenticationToken} config={config} />
        </Provider>,
        document.getElementById('react-app')
    ); // Take our FormBuilder component and attach it with DOM element "app"
}

所以现在我可以通过在 url 末尾添加 ?server=false 来简单地关闭服务器渲染，然后开始调试:)

于 2016-10-11T09:34:47.250 回答