如何将指定JSON字符串正确转换为.NET对象？

Let’s walk through the problems in your original code and fix them step by step:

Key Issues in Your Current Code #

• Mismatched JSON Structure: Your JSON is a single top-level object (not a list) containing warnings, errors, and status properties. But you’re trying to deserialize it into a List<Status>, which will fail because the JSON isn’t an array.
• Incorrect Class Definition: Your Status class doesn’t mirror the JSON structure. The JSON has nested arrays of warning/error objects (each with code and message), plus a top-level status string—your class doesn’t account for any of this.
• Logical Error: Your loop tries to access status.code, but your Status class only has a status property (and no code), which would cause a compile error.

Step 1: Define Correct Class Structures #

First, create classes that exactly match the JSON’s hierarchy:

// Represents individual warning/error entries in the JSON
public class MessageEntry
{
    public int code { get; set; }
    public string message { get; set; }
}

// Represents the entire root JSON object
public class ApiResponse
{
    public List<MessageEntry> warnings { get; set; }
    public List<MessageEntry> errors { get; set; }
    public string status { get; set; }
}

Step 2: Correct Deserialization Code #

Now adjust your code to deserialize to the proper class. Below are two approaches—one using the legacy JavaScriptSerializer, and a modern alternative recommended for newer .NET versions.

Option 1: Using JavaScriptSerializer (Legacy .NET Framework) #

string sample = "{\"warnings\":[{\"code\":3,\"message\":\"Invalid number\"}],\"errors\":[{\"code\":4,\"message\":\"No recipients specified\"}],\"status\":\"failure\"}";

JavaScriptSerializer js = new JavaScriptSerializer();
ApiResponse response = js.Deserialize<ApiResponse>(sample); // Target the root class

// Example: Access the deserialized data
string responseStatus = response.status; // Will return "failure"

foreach (var warning in response.warnings)
{
    Console.WriteLine($"Warning: Code {warning.code} - {warning.message}");
}

foreach (var error in response.errors)
{
    Console.WriteLine($"Error: Code {error.code} - {error.message}");
}

Response.Write(responseStatus); // Write the actual status instead of hardcoding "success"

Option 2: Using System.Text.Json (Modern .NET Core/.NET 5+) #

For newer .NET versions, use the built-in System.Text.Json library (no external dependencies needed):

using System.Text.Json;

string sample = "{\"warnings\":[{\"code\":3,\"message\":\"Invalid number\"}],\"errors\":[{\"code\":4,\"message\":\"No recipients specified\"}],\"status\":\"failure\"}";

ApiResponse response = JsonSerializer.Deserialize<ApiResponse>(sample);

// Access data the same way as the legacy example
string responseStatus = response.status;
// ... iterate over warnings/errors as needed

Key Fixes Explained #

• Class Alignment: The ApiResponse class maps directly to the top-level JSON properties, while MessageEntry handles each nested warning/error object.
• Correct Deserialization Target: We deserialize to a single ApiResponse object (matching the JSON’s structure) instead of a list.
• Valid Data Access: You can now properly retrieve the status string and iterate over warnings/errors to access their codes and messages.

Bonus: Newtonsoft.Json (Json.NET) Alternative #

If you prefer using Newtonsoft.Json (a popular third-party library), install the NuGet package and use this code:

using Newtonsoft.Json;

ApiResponse response = JsonConvert.DeserializeObject<ApiResponse>(sample);

内容的提问来源于stack exchange，提问作者Venkatesh