不从ajax函数调用PHP脚本

this is a noob question.

这是一个不能回答的问题。

my javascript function(part of knockout.js model that I have defined):

我的javascript函数。我定义的js模型):

self.loadData = function(){
        alert("loadData got called");
        $.ajax({
            url: 'database_connection.php',
            dataType: 'json',
            success: function(data){    //json string of records returned from server
                alert('success from server call');              

            },
            error: function(){
                alert('error from server call');            
            }

        });
    };

Contents of database_connection.php:

database_connection.php内容:

<?php
    echo "this is called";
    $db = new MySqli('localhost', 'username', 'password', 'database');
    $activities = $db->query("SELECT * FROM MainActivity");
    $activities_r = array();

    while($row = $activities->fetch_array()){
        $val = $row['mActivityID'];
        $act = $row['Name'];

        $activities_r[] = array('val'=>$val, 'act' => $act);
        }

        echo json_encode($activities_r);

?>

The php is correct, coz if I directly access this file through browser, it correctly displays the result from database table.

php是正确的，因为如果我直接通过浏览器访问这个文件，它会正确地显示来自数据库表的结果。

However, when executed through the loadData function, I get two alerts: 1. "loadData is called" 2. "error from server call"

但是，当通过loadData函数执行时，我将得到两个警报:1。“loadData叫做“2。“从服务器调用错误”

the first line of database_connection.php is not being executed since I cant see the result of echo, so that means the script is not getting called.

database_connection的第一行。php没有被执行，因为我看不到echo的结果，所以这意味着脚本没有被调用。

Am I using the ajax function wrongly?

我是否错误地使用了ajax函数?

3 个解决方案

#1

Your AJAX request contains:

AJAX请求包含:

dataType: "json"

This means that if server returns invalid JSON with a 200 OK status then jQuery fires the error function

这意味着如果服务器返回无效的JSON和200 OK状态，那么jQuery将触发错误函数。

Use the following code to ensure the reponse is JSON format.. (PHP vsersion)

使用以下代码确保响应是JSON格式。(PHP vsersion)

header('Content-Type: application/json');

Note : empty response is also considered invalid JSON; you could return {} or null which validate as JSON

注意:空响应也被认为是无效的JSON;您可以返回{}或null，该值验证为JSON

#2

you need to add headers in php file, because your data type is json in ajax call.

您需要在php文件中添加头文件，因为在ajax调用中，您的数据类型是json。

header('Content-Type: application/json');
echo json_encode($activities_r);

#3

You need to set the type of your request and may be remove dataType. Also in the success callback it was one extra bracket. Check it :

您需要设置请求的类型，可以删除数据类型。在成功回调中还有一个额外的括号。检查:

self.loadData = function(){
    alert("loadData got called");
    $.ajax({
        url: 'database_connection.php',
        type : 'GET',
        // dataType: 'json',
        sucess: function(data){     //json string of records returned from server
            alert('success from server call');              

        },
        error: function(){
            alert('error from server call');            
        }

    });
};

#1