Rails server with React Native project getting error: Unhandled promise rejection: TypeError: Object is not a function

Question

我是 Rails Ruby 的初学者。目前在 Rails 服务器上有一个 Ruby，我正试图与 React Native/Expo 应用程序进行交互。我正在使用 rails s 启动服务器，它似乎是运行以下输出

=> Booting Puma
=> Rails 5.2.4.6 application starting in development 
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.12.6 (ruby 2.6.6-p146), codename: Llamas in Pajamas
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://localhost:3000
Use Ctrl-C to stop

在另一个终端 window 我正在使用以下命令启动 postgresql 数据库：pg_ctl -D /usr/local/var/postgres start

一切似乎都很好。

我正在对服务器进行示例调用。它似乎没有到达服务器，我得到以下输出：

[Unhandled promise rejection: TypeError: Object is not a function (near '...fetch...')]
at screens/rankingsPage/Rankings.jsx:28:22 in handlePress
at screens/rankingsPage/Rankings.jsx:28:22 in handlePress
at node_modules/react-native/Libraries/Pressability/Pressability.js:691:17 in _performTransitionSideEffects
at node_modules/react-native/Libraries/Pressability/Pressability.js:628:6 in _receiveSignal
at node_modules/react-native/Libraries/Pressability/Pressability.js:524:8 in responderEventHandlers.onResponderRelease
at [native code]:null in forEach
at [native code]:null in callFunctionReturnFlushedQueue

这是我的提取调用。有谁知道问题出在哪里以及我该如何解决？谢谢。

export const emailNewAccount = async (email, password, passwordConfirmation, username) => {
  console.log("test call"); // <-- successfully logging
  const url = `${serverUrl}/api/v1/create_account`; // <-- "http://localhost:3000/api/v1/create_account
  const responseData = await fetch(url, {
    headers: { "Content-Type": "application/json" },
    method: "POST",
    body: JSON.stringify(email, password, passwordConfirmation, username)
  });

  const json = await responseData.json();
  console.log("json : ", json); // <-- not logging

  return json;
};

Answer 1

好的！您正试图在那里记录 JSON 数据，这是不可能的。它必须是一个字符串。请尝试将代码更改为此

const jsonData = await responseData 
const stringifiedData = JSON.stringify(jsonData) 
console.log("json : ", stringifiedData);

Answer 2

事实证明，在服务器上工作的人使用 node-fetch 作为导入。

import * as fetch from "node-fetch";

所以当使用 fetch 时，我们使用 node-fetch 而不是使用原生 fetch。当我们注释掉导入（或删除它）并简单地使用 React Native 原生的 fetch 时，它起作用了。

Rails server with React Native project getting error: Unhandled promise rejection: TypeError: Object is not a function

Rails server with React Native project getting error: Unhandled promise rejection: TypeError: Object is not a function

ruby

postgresql

ruby-on-rails

fetch

react-native