如果php文件中有文本，Ajax不会返回json

I'm pretty new to Jquery Ajax and sorry if that's a simple thing.

我是Jquery Ajax的新手，对不起，如果那是一件简单的事情。

So my problem here is that I want to retrieve a json object from my php file, but it only works when I echo only one Json object like this :

所以我的问题是我想从我的php文件中检索一个json对象，但只有当我只回显一个这样的Json对象时它才有效：

<?php
header('Content-type: application/json; charset=utf-8');
$arr = array ('Lastname'=>'Doe','Firstname'=>'John','Age'=>109);
echo json_encode($arr);

When I want to echo another json or some text returned as json in my javascript file, I don't get anything back from the ajax call.

当我想在我的javascript文件中回显另一个json或一些以json形式返回的文本时，我从ajax调用中得不到任何回复。

  <?php
// This code doesn't work
    header('Content-type: application/json; charset=utf-8');
    $arr = array ('Lastname'=>'Doe','Firstname'=>'John','Age'=>109);
    echo 'hi there';
    $json = 'Hello people';
    echo json_encode($json);
    echo json_encode($arr);

My ajax call is this :

我的ajax电话是这样的：

$.ajax({
        url: 'test.php',
        type: 'GET',
        success: function (response) {
            console.log(response);
        }
    });

So my final question is : what's wrong in my code, and what's not allowed in ajax call

所以我的最后一个问题是：我的代码有什么问题，以及ajax调用中不允许的内容

4 个解决方案

#1

So, the output of this code

所以，这段代码的输出

// This code doesn't work
header('Content-type: application/json; charset=utf-8');
$arr = array ('Lastname'=>'Doe','Firstname'=>'John','Age'=>109);
echo 'hi there';
$json = 'Hello people';
echo json_encode($json);
echo json_encode($arr);

Will be:

将会：

hi there"Hello people"{"Lastname":"Doe","Firstname":"John","Age":109}

Which is not valid JSON

哪个是无效的JSON

Correct way of responding with JSON is to use just one call to json_encode:

使用JSON进行响应的正确方法是只使用一次调用json_encode：

header('Content-type: application/json; charset=utf-8')
$response = [
    'message' => 'hi there',
    'people' => [
        ['Lastname'=>'Doe', 'Firstname'=>'John', 'Age'=>109],
    ],
];
echo json_encode($response);

#2

You can only put one JSON object in a response. If you have more than one thing you want to send, just make an array:

您只能在响应中放置一个JSON对象。如果您要发送多个内容，只需创建一个数组：

echo json_encode([
    'user' => ['Lastname'=>'Doe', 'Firstname'=>'John', 'Age'=>109],
    'other' => 'some other stuff',
    'more' => ['even', 'more', 'suff'],
]);

You also don't want any extraneous output before or after the JSON, so remove this:

您也不希望在JSON之前或之后有任何无关的输出，因此请删除此：

echo 'hi there';

#3

You cannot merge two JSON encoded objects as this results in invalid JSON syntax.

您无法合并两个JSON编码对象，因为这会导致无效的JSON语法。

What you can do is build a single array/object, encode into JSON and echo the resulting string.

你可以做的是构建一个数组/对象，编码成JSON并回显结果字符串。

The encoded string is the only output you can send back to the client.

编码的字符串是您可以发送回客户端的唯一输出。

#4

You cannot send multiple JSON responses via single output. Use Websockets for that or group responses into bag:

您无法通过单个输出发送多个JSON响应。使用Websockets将响应或组响应分组到包中：

json_decode([$json, $arr])

#1