PHP中的json_decode为有效json返回null

我从jquery提交的表单如下：

                    var submitForm = $('<form></form>').attr("action", "proceed.php").attr("method", "post");
                    var input = $('<input>').attr("type", "hidden").attr("name", "jsondata");//.attr("value", "");
                    var data = [];
                    elmProductSelected.children("option").each(function(n) {
                        var pIdx = $(this).attr("rel"); 
                        var pObj = products[pIdx]; 

                        var pname = pObj.manufacturer + " " + pObj.name;
                        var pdesc = pObj.description;
                        var pprice = pObj.price;
                        var pimg = pObj.img;

                        var jsonProd = new Object();
                        jsonProd.pname = pname;
                        jsonProd.pdesc = pdesc;
                        jsonProd.pprice = pprice;
                        jsonProd.pimg = pimg;

                        data.push(jsonProd);
                    });                 
                    input.attr("value",data);

                    submitForm.append(input);
                    submitForm.appendTo(document.body).submit();

if(isset($_POST["jsondata"])) {
    echo "data received :   ";
    $data = json_decode($_POST["jsondata"], true);
    var_dump($data); 
} else {
  echo 'no data received';
  die();
}

[
{
    "pname": "Yamaha AES1500 ELECTRIC GUITAR ORANGE STAIN / CASE",
    "pdesc": "AES1500 combines the classic look and tone from the golden era of full-bodied rock with the modern advantages of precision engineering. Offered with the option of the famous Bigsby vibrato tailpiece, the AES1500 combines the character of classic American archtop-electric design with Yamaha high quality construction. The semi-thinline AES1500, a classy, comfortable archtop cutaway design, is an instrument that successfully straddles the rock, country and jazz genres. The two custom Q100 DiMarzio humbuckers possess a powerful warmth perfectly balanced by the clear, well defined cut-through of the maple body construction. Moreover, each pickup can be coil split, which in conjunction with the three-way pickup selector lends a whole new dimension of tonal versatility and subtlety.",
    "pprice": 207101.43,
    "pimg": "5b2f8d703c899290cbcbe325058dfaeb"
},
{
    "pname": "Yamaha AES1500 ELECTRIC GUITAR RED STAIN / CASE",
    "pdesc": "AES1500 combines the classic look and tone from the golden era of full-bodied rock with the modern advantages of precision engineering. Offered with the option of the famous Bigsby vibrato tailpiece, the AES1500 combines the character of classic American archtop-electric design with Yamaha high quality construction. The semi-thinline AES1500, a classy, comfortable archtop cutaway design, is an instrument that successfully straddles the rock, country and jazz genres. The two custom Q100 DiMarzio humbuckers possess a powerful warmth perfectly balanced by the clear, well defined cut-through of the maple body construction. Moreover, each pickup can be coil split, which in conjunction with the three-way pickup selector lends a whole new dimension of tonal versatility and subtlety.",
    "pprice": 207101.43,
    "pimg": "5b2f8d703c899290cbcbe325058dfaeb"
}
]

我从服务器上得到的是：

data received : NULL

我的JSON是有效的，用

http://jsonlint.com/

它看起来是这样的：

                    var submitForm = $('<form></form>').attr("action", "proceed.php").attr("method", "post");
                    var input = $('<input>').attr("type", "hidden").attr("name", "jsondata");//.attr("value", "");
                    var data = [];
                    elmProductSelected.children("option").each(function(n) {
                        var pIdx = $(this).attr("rel"); 
                        var pObj = products[pIdx]; 

                        var pname = pObj.manufacturer + " " + pObj.name;
                        var pdesc = pObj.description;
                        var pprice = pObj.price;
                        var pimg = pObj.img;

                        var jsonProd = new Object();
                        jsonProd.pname = pname;
                        jsonProd.pdesc = pdesc;
                        jsonProd.pprice = pprice;
                        jsonProd.pimg = pimg;

                        data.push(jsonProd);
                    });                 
                    input.attr("value",data);

                    submitForm.append(input);
                    submitForm.appendTo(document.body).submit();

if(isset($_POST["jsondata"])) {
    echo "data received :   ";
    $data = json_decode($_POST["jsondata"], true);
    var_dump($data); 
} else {
  echo 'no data received';
  die();
}

[
{
    "pname": "Yamaha AES1500 ELECTRIC GUITAR ORANGE STAIN / CASE",
    "pdesc": "AES1500 combines the classic look and tone from the golden era of full-bodied rock with the modern advantages of precision engineering. Offered with the option of the famous Bigsby vibrato tailpiece, the AES1500 combines the character of classic American archtop-electric design with Yamaha high quality construction. The semi-thinline AES1500, a classy, comfortable archtop cutaway design, is an instrument that successfully straddles the rock, country and jazz genres. The two custom Q100 DiMarzio humbuckers possess a powerful warmth perfectly balanced by the clear, well defined cut-through of the maple body construction. Moreover, each pickup can be coil split, which in conjunction with the three-way pickup selector lends a whole new dimension of tonal versatility and subtlety.",
    "pprice": 207101.43,
    "pimg": "5b2f8d703c899290cbcbe325058dfaeb"
},
{
    "pname": "Yamaha AES1500 ELECTRIC GUITAR RED STAIN / CASE",
    "pdesc": "AES1500 combines the classic look and tone from the golden era of full-bodied rock with the modern advantages of precision engineering. Offered with the option of the famous Bigsby vibrato tailpiece, the AES1500 combines the character of classic American archtop-electric design with Yamaha high quality construction. The semi-thinline AES1500, a classy, comfortable archtop cutaway design, is an instrument that successfully straddles the rock, country and jazz genres. The two custom Q100 DiMarzio humbuckers possess a powerful warmth perfectly balanced by the clear, well defined cut-through of the maple body construction. Moreover, each pickup can be coil split, which in conjunction with the three-way pickup selector lends a whole new dimension of tonal versatility and subtlety.",
    "pprice": 207101.43,
    "pimg": "5b2f8d703c899290cbcbe325058dfaeb"
}
]

如果我不发送此数据，而是发送以下内容：

var a ="{\"id\":\"1\"}";                        
input.attr("value",a);

服务器成功获取json:

data received : array(1) { ["id"]=> string(1) "1" }

问题：第一个请求可能有什么问题

谢谢。

输入.attr（“值”，数据）设置默认值，而不是当前值。要设置当前值，请使用

.val（）

此外，问题的真正原因是您拥有的是一个对象，而不是json。如果要将其作为json发送，则应将其转换为json，否则实际上会发送无效的json

[object object，object object]

input.val(JSON.stringify(data));

---

请发布完整的PHP代码（一个有问题的工作示例）在json_解码之前？因为解码你发布的json对Metat是有效的。转储接收到的JSON，而不是调试此代码的解码结果。@DonRhummy，这是完整的代码。@NielsKeurentjes他正在向服务器发送（或试图发送）JSON，而不是从服务器接收。是的，就是这样。谢谢