Question

解决方案（尽管我仍然喜欢解释）

如果我在preload.ts文件的TOP中直接包含接口代码（不导入），则一切正常。我可以像预期的那样投射对象。

我有一个电子应用程序编译为打字稿。如启动器example here所示，我有一个main.ts和一个preload.ts。当我将文件导入preload.ts时，应用会在使用导入的位置崩溃。我在这里做错了什么？

错误提示：

api未定义

这是完全不正确的，因为如果在以下标记的行中删除了CandleRes导入，则代码可以正常工作。

经过一些测试，我发现：

import语句本身似乎不会引起问题。当我删除导入并将接口直接放在文件中时，我仍然遇到相同的错误
当我通过复制并粘贴preload.ts文件（位于底部）来包含界面时，文件崩溃了，无论我是否对界面进行任何引用

main.ts

import { app, BrowserWindow } from "electron";
import * as path from "path";

let mainWindow: Electron.BrowserWindow;

function createWindow() {
  // Create the browser window.
  mainWindow = new BrowserWindow({
    height: 600,
    webPreferences: {
      preload: path.join(__dirname, "preload.js")
    },
    width: 800
  });

  // and load the index.html of the app.
  mainWindow.loadFile(path.join(__dirname, "../index.html"));

}

app.on("ready", createWindow);

app.on("activate", () => {
  // On OS X it"s common to re-create a window in the app when the
  // dock icon is clicked and there are no other windows open.
  if (mainWindow === null) {
    createWindow();
  }
});

preload.ts

import { CandleRes } from "./models"; //<<<<<<<<<<<<<<<<<<<<<<<<<<<<<THIS LINE CAUSES CRASH
let api: any;

// All of the Node.js APIs are available in the preload process.
// It has the same sandbox as a Chrome extension.

window.addEventListener("DOMContentLoaded", async () => {
  replaceText("colnames", "Loading data...."); //<<<<<<<<<<THIS FIRES CORRECTLY
  setupApi(); //Omitted to save space. This inits the var api
  await getDataAsync();
});

async function getDataAsync() {
  try {
    let candles: CandleRes = ( //<<<<<<<<<<<<<<<<<<<<<<<<<<<<I attempt to use import here. App crashes
      await this.api.getCandles("USD_CAD", {
        granularity: "M5",
        count: 1
      })
    ).data;
    replaceText("currencies", candles + " string: " + JSON.stringify(candles));
  } catch (e) {
    replaceText("currencies", "currencies ERR: " + e);
  }
}
const replaceText = (selector: string, text: string) => {
  const element = document.getElementById(selector);
  if (element) {
    element.innerText = selector + ":" + text;
  }
};
function setupApi() {
  var key = "xxxxxxxxxxxxxxxxxxxxxxx"; //https://www.oanda.com/demo-account/tpa/personal_token
  var acctid = "xxx-xxx-xxx-xxx"; //https://www.oanda.com/demo-account/funding
  const Oanda = require("oanda-node-api");

  const config = {
    env: "fxPractice",
    auth: `Bearer ${key}`,
    accountID: acctid,
    dateFormat: "RFC3339"
  };

  this.api = Object.create(Oanda);
  this.api.init(config);
}

models.ts

export interface OHLC {
  o: string; // "1.34288"
  h: string; //"1.34336"
  l: string; //1.34278"
  c: string; //1.34315"
}

export interface Candle {
  complete: boolean; //true
  volume: number; //283
  time: string; //2020-02-28T17:50:00.000000000Z
  mid: OHLC;
}

//{"instrument":"USD_CAD","granularity":"M5",
//"candles":[
//{"complete":true,"volume":90,"time":"2020-02-28T21:55:00.000000000Z",
//"mid":{"o":"1.33974","h":"1.33974","l":"1.33932","c":"1.33968"}}]}
export interface CandleRes {
  instrument: string; //ex: "USD_CAD"
  granularity: string; //ex "M5"
  candles: Candle[];
}

Answer 1

您在全局范围内声明了@SupportedValidationTarget(ValidationTarget.PARAMETERS) public class MyCheckValidator implements ConstraintValidator<MyCheck, Object[]> { @Override public boolean isValid( Object[] value, ConstraintValidatorContext context) { if( value.length <2 ) { return true; } if ( ! value[0].equals(value[1].myField()) { return false; } return true; } }变量，并且您尝试使用api在函数内部访问它，这是不正确的。只要看看电子示例在this.api中如何使用mainWindow。

您在main.ts中执行一次，在getDataAsync()中进行两次。将您所有的setupApi()更改为this.api，这个特殊的问题就应该解决了。

如果您想扩展该领域的知识，请阅读以下精彩文章：'this' in TypeScript

导入文件时电子应用程序崩溃了

1 个答案: