jQuery AJAX 如何使用对象数组？

Question

所以我有两个文件：index.php 和 query.php。

问题是，我不知道如何使用ajax 检索到的数组（msg.d）。我的数组的输出是：

{"s":0,"d":[{"userPostID":"1","userID":"1","postID":"1","choice":"1"},{"userPostI‌​D":"2","userID":"1","postID":"2","choice":"0"},{"userPostID":"3","userID":"1","pos‌​tID":"3","choice":"1"}]}

我想要做的是遍历数组以便

while (i < array.length){ 
      if (msg.d[i]['choice'] = 1) {
           //do something with msg.d[i]['postID']
      } else if (msg.d[i]['choice'] = 0) {
           //do something else with msg.d[i]['postID']
      }
      i++
}

我以前从未使用过对象数组，从我所能收集到的数据来看，我正在尝试做的事情相当复杂，我无法弄清楚我找到的示例。

index.php

<script type="text/javascript">
$(document).ready(function() {
// set $checked values

    $.ajax({
        url: 'query.php',
        type: 'POST',
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        async: true,
        cache: false,
        success: function (msg) {
                console.log(msg);
                },
        error: function (x, e) {
            alert("The call to the server side failed.");
        }
    });
});
</script>

<?php
$data = mysql_query("SELECT * FROM Posts LEFT JOIN userPosts ON Posts.postID = userPosts.postID AND userPosts.userID = $userID") or die(mysql_error());

while($row = mysql_fetch_array( $data )){
?>

查询.php

<?php

$query = mysql_query("SELECT * FROM userPosts WHERE userPosts.userID = $userID") or die(mysql_error());

if (mysql_num_rows($query) == 0)
{
echo 'error';
}
else
{

echo json_encode(mysql_fetch_assoc($query));
}
?>

我知道，我很接近... 没有错误！

Answer 1

试试这样的：

您需要解析成功时的响应http://api.jquery.com/jQuery.parseJSON/

然后循环遍历它http://api.jquery.com/jQuery.each/

$.ajax(
        {
            type: "POST",
            url: 'query.php',
            data: 'userID=' + userID,
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            async: true,
            cache: false,
            success: function (msg) {
                var obj = $.parseJSON(msg);
                    $.each(obj, function(i, val) {
                        alert(JSON.stringify(val));
                    });
            },
            error: function (x, e) {
                alert("The call to the server side failed.");
            }
        });

Answer 2

我认为您想要做的是将整个记录集获取到一个数组中，然后将其作为 JSON 传递给客户端。现在，您只需拨打mysql_fetch_assoc 一次。这意味着您只能获得第一行。

我的设置方式是这样的（注意 - 我没有测试过这段代码）：

query.php

<?php
$query = mysql_query("SELECT * FROM userPosts WHERE userPosts.userID = $userID");

// Return array contents:
// s = Status value, d = Data
// s == 0 -> Success
// s == 1 -> Error
// s == 2 -> No rows returned
$rtrn = array('s' => 1, 'd' => array());
//Check for error
if (mysql_errno() == 0) {
    //Check for no rows returned
    if (mysql_num_rows($query) == 0) {
        $rtrn['s'] = 2;
    } else {
        //Set status value to 0
        $rtrn['s'] = 0;
        //Get all rows from the query
        while($row = mysql_fetch_array($query)){
            //Append row to the data array
            $rtrn['d'][] = $row;
        }
    }
}
//Echo the return array
echo json_encode($rtrn);
?>

index.php（仅成功回调）

success: function (msg) {
    if (msg.s == 0) {
        //Loop through returned data array using: msg.d
        //For example: msg.d[0] is the first row.
    } else if (msg.s == 2) {
        alert('No rows returned!');
    } else {
        alert('Error!');
    }
},

基本上，我在这里所做的是确保始终返回 JSON 对象，即使在错误期间也是如此。该对象有一个状态部分，所以你知道发生了什么，还有一个数据部分，所以你可以返回信息。对于状态，0 始终是成功，1 始终是错误，但您可以将其他数字用于不同的结果，例如不返回任何记录。这使您可以使您的应用程序更加健壮。

如果其中任何一项无法正常工作，请告诉我，因为正如我所说，我还没有测试过。

Answer 3

我想通了！

<script type="text/javascript">
$(document).ready(function() {
// set $checked values

    $.ajax({
        url: 'query.php',
        type: 'POST',
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        async: true,
        cache: false,
        success: function (msg) {
                if (msg.s == 0) {
                    //Loop through returned data array using: msg.d
                    for (var key in msg.d) {
                        var obj = msg.d[key];
                        for (var prop in obj) {
                            if (prop == "postID"){
                                if (obj['choice'] == 1){
                                //do something with liked posts.
                                } else if (obj['choice'] == 0){
                                //do something with disliked posts.
                                }
                            }
                        }
                    }
                } else if (msg.s == 2) {
                    alert('No rows returned!');
                } else {
                    alert('Error!');
                }
            },
        });
    });
</script>