JSON API 响应中包含不需要的额外数组

问：

我想在处理输入后发送一个 JSON 响应，我将 Datatable 转换为 JSON 并发送它，但它包含在一个新数组中'd' : []

这是我的API JSON输入：

{
    "region_id": "ID-10",
    "document_number": "10-80/81-BIN-00005",
    "industry_no": "10-CNO-0001",
    "posting_date": "14-07-2080",
    "customer_number": "10-CNO-0001",
    "payment_for": [
      {"BillType": "पानी महशुल"}
 ] }

这是我的 API 响应。 我不确定为什么会出现："d"

{  
    "d": "[{\"CustomerNo\":\"10-CNO-0001\",\"PostingDate\":\"2023-10-31T00:00:00\",\"DocumentNo\":\"10-80/81-BIN-00005\",\"BillType\":\"5\",\"Description\":\"पानी महशुल\",\"Quantity\":0.00000,\"Rate\":0.00000,\"Amount\":1000.00,\"RegionID\":\"ID-10\",\"ExpenseID\":\"0\",\"ActivityID\":\"0\",\"SubActivityID\":\"0\",\"Dimension5ID\":\"\",\"FineAmount\":0.00,\"DiscountAmount\":-40.00,\"IsPaid\":false,\"priority\":\"2\",\"billType\":\"5\"}]"  
}

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
[AllowAnonymous]
public string InitialFetch(string region_id, string document_number, string industry_no, string posting_date, string customer_number, List<PaymentForItem> payment_for)
{
    try
    {
        // Create a dictionary to represent the processed data
        var extractedData = new Dictionary<string, object>
        {
            { "region_id", region_id },
            { "document_number", document_number },
            { "industry_no", industry_no },
            { "posting_date", posting_date },
            { "customer_number", customer_number },
            { "payment_for", payment_for.Select(item => new Dictionary<string, object> { { "BillType", item.BillType } }).ToList() }
        };

        // Call the original GetReceivableByBillTypeFromLaravel method a datatable is extracted 
        DataTable receiptData = GetReceivableByBillTypeFromLaravel(extractedData);

        // Serialize the response to JSON
        string jsonResponse = JsonConvert.SerializeObject(receiptData);

        return jsonResponse;
    }
    catch (Exception ex)
    {
        // Handle any exceptions and return an error response
        return JsonConvert.SerializeObject(new { error = "Error: " + ex.Message });
    }
}

上面是我处理 API 的代码。

我有另一组方法可以实际制定数据表，如果需要，我也会发布它。GetReceivableByBillTypeFromLaravel