Question

我尝试用Ajax调用php函数。这是我的html文件中的JavaScript代码：

<script type="text/javascript">
    function ajax(){
        $.ajax({
            type:"POST",
            url: "SQLCommunication.php",
            dataType: "JSON",
            success : function(json){
                json = jQuery.parseJSON(json);
                alert(json.value);
            }
        }
        )
    }

    $("#btn_refresh").click(function(){
       ajax(); 
    });
</script>

我不知道是否必须指定我真正想要调用哪个PHP函数？我也不知道我是怎么做到的。

我的PHP功能：

header('Content-Type: application/json');
function readValue(){
    $conn = establishConnection();
    if($conn->connect_error){
        die("Connection failed: " . $conn->connect_error);
    }

    $sql = "SELECT datetime, value FROM tempvalues";
    $result = $conn->query($sql);

    if($result->num_rows > 0){
        $row = $result->fetch_assoc();
        $arr["datetime"] = $row["datetime"]; //return datetime and value as array
        $arr["value"] = $row["value"];
        if(is_ajax()){
            return json_encode($arr);
        } else {
            return $arr;
        }
    }

    $conn->close();
}

现在问题是，如果我按下按钮就没有任何反应。

Answer 1

如果你想在你的ajax响应中看到结果，你必须在控制器中使用echo（）或任何其他打印方法而不是返回

Answer 2

我会改写自己的风格

<强>的jQuery

<script type="text/javascript">
    $("#btn_refresh").click(function(){
        $.ajax({
            type:"POST",
            url: "SQLCommunication.php",
            dataType: "JSON",
            success : function(data){
                console.log(data);
                if(data.status === "success"){
                    alert("success");
                }else{
                    alert("error");
                }
            }
            error : function(XHR, status){
                 alert("fatal error");
            }
        })
    });
</script>

<强> PHP

header('Content-Type: application/json');
function readValue(){
    $conn = establishConnection();
    if($conn->connect_error){
        die("Connection failed: " . $conn->connect_error);
    }

    $sql = "SELECT datetime, value FROM tempvalues";
    $result = $conn->query($sql);

    if($result->num_rows > 0){
        $row = $result->fetch_assoc();
        $arr["datetime"] = $row["datetime"]; //return datetime and value as array
        $arr["value"] = $row["value"];
        $arr["status"] = "success";
    }else{
        $arr["status"] = "error";
    }

    return json_encode($arr);
    $conn->close();
}

echo readValue();

未测试

更新

的functions.php

function readValue(){
    $conn = establishConnection();
    if($conn->connect_error){
        die("Connection failed: " . $conn->connect_error);
    }

    $sql = "SELECT datetime, value FROM tempvalues";
    $result = $conn->query($sql);

    if($result->num_rows > 0){
        $row = $result->fetch_assoc();
        $arr["datetime"] = $row["datetime"]; //return datetime and value as array
        $arr["value"] = $row["value"];
        $arr["status"] = "success";
    }else{
        $arr["status"] = "error";
    }

    return json_encode($arr);
    $conn->close();
}

function writeValue(){
     ...
}

SQLCommunication.php

header('Content-Type: application/json');
if(!isset($_GET['func']) && empty($_GET['func'])){
   //make the file inaccessible without $_GET
   $arr['status'] = "error";
   echo json_encode($arr);
   exit();
)

if($_GET['func'] === "readvalue"){
   echo readValue();
}elseif($_GET['func'] === "writevalue"){
   echo writeValue();
}elseif($_GET['func'] === "whatever"){
   //whatever...
}

  ....

的jQuery

$("#btn_refresh").click(function(){
    $.ajax({
        type:"POST",
        url: "SQLCommunication.php?func=readvalue", //SQLCommunication.php?func=writevalue
        dataType: "JSON",
        success : function(data){
            console.log(data);
            if(data.status === "success"){
                alert("success");
            }else{
                alert("error");
            }
        }
        error : function(XHR, status){
             alert("fatal error");
        }
    })
});

使用JavaScript Ajax调用PHP函数以获取数据库值

2 个答案: