如何在Kotlin中解析JSON数组 [英] How do I parse through JSON Arrays in Kotlin

问题描述

所以我正在开发一个Android应用程序，我需要从mysql数据库中获取用户列表，并将其数据放入kotlin应用程序中的User类中.

so I am working on an Android app and I need to get a list of users from my mysql database and put their data into a User class in my kotlin app.

php api正常工作，我在JSON中收到Postman的以下响应:

The php api is working correctly and I get this response with Postman in JSON:

{
    "id": "5f69bbc1b264c6.07041576",
    "username": "Test F",
    "email": "[e-mail]",
    "profileimagepath": "../uploads/profileimages/5f69bbc1b264c6.07041576.jpg"
}{
    "id": "5f69c5708632f7.37478122",
    "username": "Test H",
    "email": "[e-mail]",
    "profileimagepath": "../uploads/profileimages/5f69c5708632f7.37478122.jpg"
}

kotlin中的用户类如下:

The user class in kotlin looks like this:

class UserItem(val id: String, val username: String, val email: String){
    constructor(): this("","","")
}

https请求的响应侦听器如下所示:

And the response listener for the https request looks like this:

val request = JsonObjectRequest(Request.Method.POST,url,jsonObject,
            Response.Listener { response ->
                // Process the json
                try {
                    Log.d("loadTag", response.toString())
                    if(response.getString("error") == "false"){
                        Toast.makeText(applicationContext, "Loading completed!", Toast.LENGTH_SHORT).show()
                    }
                    else if(response.getString("error") == "true" && response.getString("message") == "Invalid code"){
                        Toast.makeText(applicationContext, "Invalid code.", Toast.LENGTH_LONG).show()
                    }
                    else if(response.getString("error") == "true" && response.getString("message") == "Required Parameters are missing"){
                        Toast.makeText(applicationContext, "Invalid user details or fields are empty.", Toast.LENGTH_LONG).show()
                    }
                    else if(response.getString("error") == "true"){
                        Toast.makeText(applicationContext, "Error. Something went wrong. Please try again.", Toast.LENGTH_LONG).show()
                    }

                }catch (e:Exception){
                    Toast.makeText(applicationContext, "Something went wrong. Please try again.", Toast.LENGTH_LONG).show()
                }

            }, Response.ErrorListener{
                // Error in request
                Toast.makeText(applicationContext, "Error in http request. Please contact the developer.", Toast.LENGTH_LONG).show()
            })

我已经尝试了很多东西，在这里和其他帖子上都读到了，但是我总是只得到一行(用户"Test F")

I've tried so many things that I've read here and on other posts but I always only get one row (user "Test F")

使用杰克逊进行更新

我仍然只有一个使用此代码的用户

I still get only one of the users using this code

when {
                        response.getString("error") == "true" && response.getString("message") == "Required Parameters are missing" -> {
                            Toast.makeText(applicationContext, "Invalid user details or fields are empty.", Toast.LENGTH_LONG).show()
                        }
                        response.getString("error") == "true" -> {
                            Toast.makeText(applicationContext, "Something went wrong. Please try again.", Toast.LENGTH_LONG).show()
                        }
                        else -> {
                            val mapper = ObjectMapper()
                            val users: UserItem = mapper.readValue(response.toString(), UserItem::class.java)
                            System.out.println(users)
                            Toast.makeText(applicationContext, "Loading completed.", Toast.LENGTH_LONG).show()
                        }
                    }

我通过以下代码从api获得json响应:

I get my json response from the api through this code:

$stmt2 = $this->con->prepare("SELECT id,username,email FROM accounts WHERE id=?");
                $stmt2->bind_param("s", $friendsArray2);
                if($stmt2->execute()){
                    $result2 = $stmt2->get_result();
                    $num_of_rows2 = $result2->num_rows;
                    while($row2 = mysqli_fetch_assoc($result2)){
                        $index++;
                        $index2++;
                        echo json_encode($row2);
                    }
                }

还有更多代码，但这是给我响应的部分，因为我希望在sql语句中找到行

There is more code but this is the part that gives me the response as I want the rows found in the sql statement

推荐答案

已经有一段时间没有使用PHP了，但是如果我理解正确的话，您想将对象数组作为Json服务.

Haven't used PHP for a while, but if I understand correctly you want to serve the array of Objects as Json.

$stmt2 = $this->con->prepare("SELECT id,username,email FROM accounts WHERE id=?");
$stmt2->bind_param("s", $friendsArray2);
if($stmt2->execute()){
    $result2 = $stmt2->get_result();
    $num_of_rows2 = $result2->num_rows;
    $result_array = array();
    while($row2 = mysqli_fetch_assoc($result2)){
        $index++;
        $index2++;
        result_array[] = $row2;
    }

    echo json_encode(result_array);  // echo or do whatever with the encoded json
}

这会将所有行数据推送到数组，最后将数据编码为正确的Json表示形式，然后回显(输出)到控制台/服务器.

This will push all the row data to the array, and finally will encode the data as a proper Json representation, then will echo (output) to the console/server.

然后，您可以使用 kotlinx.serialization 轻松地将JsonArray解码为列表:

And then you can easily decode the JsonArray into list using kotlinx.serialization:

@Serializable 
data class Project(val id: String, val username: String, val email: String)

// response <= the Json response body, you get from HTTP response
val list: List<UserItem> = JSON.parse(UserItem.serializer().list, response)

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