如何使用 fetch 发送数组？（Javascript）

Question

我正在尝试使用 fetch 发送一个数组，如下所示：

{"cards":[[189,2],[211,2],[238,2],[778,2],[985,2],[1008,2],[1073,2],[1171,2],[48886,2],[49161,2],[49164,2],[49184,1],[49356,2],[50372,2],[51722,1],[52422,2]],"heroes":[1066],"format":2}

这是我正在尝试的：

 getCardsForDeck = deck => {
    var stringifiedDeck = JSON.stringify(deck);
    console.log("stringifiedDeck:" + stringifiedDeck);
    fetch(`http://localhost:3001/api/getCardsForDeck`, {
      method: "PUT",
      body: stringifiedDeck
    })
      .then(cards => cards.json())
      .then(res => this.setState({ cards: res.cards }));
  };

我收到一个错误：

Unhandled Rejection (SyntaxError): Unexpected token < in JSON at position 0

如果不使用 JSON.stringify() 或我是否必须编辑数据以删除括号，我该如何发送这些数据？

检查网络选项卡中的api后，它给了我这个：

     SyntaxError: Unexpected token o in JSON at position 1
[0]     at JSON.parse (<anonymous>)
[0]     at parse (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\body-parser\lib\types\json.js:89:19)
[0]     at C:\Users\User\projects\webapp\deck-editor\backend\node_modules\body-parser\lib\read.js:121:18
[0]     at invokeCallback (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:224:16)
[0]     at done (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:213:7)
[0]     at IncomingMessage.onEnd (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:273:7)
[0]     at IncomingMessage.emit (events.js:194:15)
[0]     at endReadableNT (_stream_readable.js:1125:12)
[0]     at process._tickCallback (internal/process/next_tick.js:63:19)
[0] SyntaxError: Unexpected token o in JSON at position 1
[0]     at JSON.parse (<anonymous>)
[0]     at parse (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\body-parser\lib\types\json.js:89:19)
[0]     at C:\Users\User\projects\webapp\deck-editor\backend\node_modules\body-parser\lib\read.js:121:18
[0]     at invokeCallback (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:224:16)
[0]     at done (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:213:7)
[0]     at IncomingMessage.onEnd (C:\Users\User\projects\webapp\deck-editor\backend\node_modules\raw-body\index.js:273:7)
[0]     at IncomingMessage.emit (events.js:194:15)
[0]     at endReadableNT (_stream_readable.js:1125:12)
[0]     at process._tickCallback (internal/process/next_tick.js:63:19)

Answer 1

你似乎在期待http://localhost:3001/api/getCardsForDeck送JSON回您发送JSON后给它。它很可能是用 HTML 响应，而不是 JSON。

该代码中还有另外两个错误：

1. 您需要说明要发送的内容，因为它不是默认的 URI 编码数据：

   fetch(`http://localhost:3001/api/getCardsForDeck`, {
     method: "PUT",
     body: stringifiedDeck,
     headers: {                              // ***
       "Content-Type": "application/json"    // ***
     }                                       // ***
   })
   

2. 您需要检查响应的状态。（每个人都会错过这一点。）最简单的方法是检查ok响应上的标志：

   fetch(`http://localhost:3001/api/getCardsForDeck`, {
     method: "PUT",
     body: stringifiedDeck,
     headers: {
       "Content-Type": "application/json"
     }
   })
   .then(response => {
     if (!response.ok) {                                  // ***
       throw new Error("HTTP error " + response.status);  // ***
     }                                                    // ***
     // ...use `response.json`, `response.text`, etc. here
   })
   .catch(error => {
     // ...handle/report error
   });