Unity HTTP下载配置变更及WWW上传JSON至数据库问题咨询

Hey there, let's break down why your second JSON upload method is failing and fix it up. First, let's recap your setup to make sure we're on the same page:

You've got two serializable classes for your data:

[Serializable]
public class pushdatawrapper{
    public string email;
    public pushdata[] shotsArray=new pushdata[1];
}
[Serializable]
public class pushdata{
    public string timehappened;
    public string clubtype;
    public pushdata(string timestamp_,string clubtype_) {
        timehappened = timestamp_;
        clubtype = clubtype_;
    }
}

And you're using Unity's WWW class to upload data to a database—one method works, the other throws exceptions. Let's dive into the most common culprits here.

The #1 Cause: Unity's JsonUtility Hates Parameterized Constructors #

Unity's built-in JsonUtility (which you're almost certainly using to serialize your data) has a strict requirement: all serializable classes must have a parameterless (no-args) constructor. Your pushdata class only has a constructor that takes two strings, which breaks JsonUtility's ability to instantiate objects during serialization/deserialization.

This is probably why your second method fails—if it's relying on direct serialization of pushdata instances created with that constructor, or trying to deserialize incoming JSON back into pushdata objects, JsonUtility can't create the instances properly.

Fixes to Get Your Second Method Working #

1. Add a Parameterless Constructor to pushdata #

Update your pushdata class to include an empty constructor. You can keep your parameterized one for manual object creation:

[Serializable]
public class pushdata{
    public string timehappened;
    public string clubtype;

    // Required for JsonUtility
    public pushdata() {}

    public pushdata(string timestamp_,string clubtype_) {
        timehappened = timestamp_;
        clubtype = clubtype_;
    }
}

2. Never Serialize Arrays Directly (Use Your Wrapper!) #

If your second method tries to serialize the pushdata[] array directly (without wrapping it in pushdatawrapper), JsonUtility won't handle it correctly. Unity's JsonUtility doesn't support top-level arrays—they need to be nested inside a serializable class (which is exactly what your pushdatawrapper is for).

Bad (will fail):

string badJson = JsonUtility.ToJson(shotsArray); // Won't work for top-level arrays

Good (what your working method is probably doing):

pushdatawrapper wrapper = new pushdatawrapper();
wrapper.shotsArray = new pushdata[] { new pushdata("2024-05-20", "Iron") };
string goodJson = JsonUtility.ToJson(wrapper);

3. Ensure You're Setting the Correct Request Header #

When uploading JSON with WWW, you need to tell the server you're sending JSON data by setting the Content-Type header. If your second method skips this, the backend might reject or misparse your data:

Dictionary<string, string> headers = new Dictionary<string, string>();
headers.Add("Content-Type", "application/json");

byte[] jsonBytes = Encoding.UTF8.GetBytes(serializedJson);
WWW www = new WWW("your-database-url", jsonBytes, headers);
yield return www;

4. Ditch WWW for UnityWebRequest (Bonus!) #

Quick heads-up: Unity's WWW class is obsolete now. The official replacement is UnityWebRequest, which is more efficient, has better error handling, and supports modern web features. Here's how you'd rewrite your upload with it:

using UnityEngine.Networking;

// ...

pushdatawrapper wrapper = new pushdatawrapper();
wrapper.email = "player@example.com";
wrapper.shotsArray[0] = new pushdata(DateTime.Now.ToString(), "Driver");

string json = JsonUtility.ToJson(wrapper);
byte[] jsonBytes = Encoding.UTF8.GetBytes(json);

UnityWebRequest request = UnityWebRequest.PostWwwForm("your-database-url", "");
request.uploadHandler = new UploadHandlerRaw(jsonBytes);
request.SetRequestHeader("Content-Type", "application/json");

yield return request.SendWebRequest();

if (request.result != UnityWebRequest.Result.Success) {
    Debug.LogError($"Upload failed: {request.error}");
} else {
    Debug.Log($"Upload successful! Response: {request.downloadHandler.text}");
}

Common Second-Method Pitfalls to Check #

• Did you forget to initialize the shotsArray properly (e.g., leaving it as null instead of creating a new array instance)?
• Are you trying to deserialize the server's response back into a pushdata array without a wrapper?
• Did you accidentally use a different serialization library (like Newtonsoft Json) that has different requirements than Unity's JsonUtility?

内容的提问来源于stack exchange，提问作者batuman