如何在C＃中将类对象转换为json数组？ [英] How to convert class object to json array in C#?

问题描述

我通过winform调用web api，当我将数据传递给类并调用函数时，它向我显示错误。

无法将当前JSON对象（例如{name：value}）反序列化为类型Properties.Model.Tenant.TenantListItem []，因为该类型需要JSON数组（例如[ 1,2,3]）正确反序列化。

我尝试过：

 [DataContract] 
  public   class  TenantFilter 
 {
 [DataMember] 
  public   string  TenantName { get ;  set ; } 
 [DataMember] 
  public   long  AreaID {获得;  set ; } 
} 
 
  //  我的网络API代码 
 
  public   async 任务< list>< tenantlistitem>> GetAllTenant（TenantFilter过滤器）
 {
  var  result =  new 列表< tenantlistitem> （）; 
 尝试 
 {
  var  response =  await  TenantCore.LoadTenantGrid（filter）; 
  if （response！=  null ）
 {
 result = （列表与LT; tenantlistitem>）响应; 
 
} 
} 
  catch （System.Exception ex）
 {
 
 
} 
 返回结果; 
} 
  //  通过winform调用 
  private   async 任务< ienumerable>< tenantlistitem>> PopulateTenantGridView（）
 {
  var  result =  new 列表< tenantlistitem>（） ; 
 尝试 
 {
 使用（ var  client =  new  HttpClient（））
 {
  var  name = txtName.Text; 
  var  area =（cmbArea.SelectedValue ==  null ？ 0  :(  long ）cmbArea.SelectedValue）; 
 
  var  tenantfilter =  new  TenantFilter 
 {
 TenantName = name，
 AreaID = area 
}; 
 
  var  serializedProduct = JsonConvert.SerializeObject（tenantfilter，Formatting.Indented）; 
  var  content =  new  StringContent（serializedProduct，Encoding.UTF8，  application / json）; 
  var  response =  await  client.PostAsync（   http：// localhost：64456 / api / Tenant / GetAllTenant /，content）; 
 
  if （response.IsSuccessStatusCode）
 {
  var  Jsonstring =  await  response.Content.ReadAsStringAsync（）; 
  var  tenant = JsonConvert.DeserializeObject< tenantlistitem [] > （Jsonstring）.ToList（ ）; 
 如果（租户！=  null ）
 {
 
 result = tenant.Take（ 100 ）。ToList（）; 
} 
} 
} 
 
} 
  catch （例外情况）
 {
 MessageBox.Show（ex.Message）; 
 
} 
 返回结果; 
} 

解决方案

那是因为，你的JSON可能只是这样，

< pre lang =c＃> { / * 此处的文档数据。 * / }

但是，您执行的代码要求您的JSON文档包含对象数组，以<$ c开头$ c> [并以结尾] 。这是您遇到的错误。更新服务器上的JSON文档，以便您的客户端代码可以正常工作。如果这不起作用，那么你必须自己使用 try ... catch 块来解决问题。



阅读我写的以下文章以及我之前的一些答案，这些文章将帮助您更好地理解这个概念：



使用C＃从JSON中的零到英雄 [ ^ ]

http://www.codeproject.com/Answers/1109587/How-to-deserialize-my-json-data-to-relevent-object#answer1 [ ^ ]

http ：//www.codeproject.com/Answers/836988/how-to-remove-d uplicate-a-json-file＃answer2 [ ^ ]

http://www.codeproject.com/Answers/879055/How-do-I-get-Ajax-to -read-my-json-string＃answer1 [ ^ ]

http://www.codeproject.com/Answers/828795/How-do-I-write-a- Csharp-program-to-read-json-data＃answer2 [ ^ ]

  VAR  tenantfilter =  new  TenantFilter 
 {
 TenantName = name，
 AreaID = area 
}; 
 
  var  serializedProduct = JsonConvert.SerializeObject（tenantfilter，Formatting.Indented）; 

此序列化为1个对象{name：value}您可以将代码更改为：

  var  tenantfilter =  new  TenantFilter 
 {
 TenantName = name，
 AreaID = area 
}; 
 
  var  tenantFilterList =  new  List< tenantfilter>（）; 
 tenantFilterList.Add（tenantFilter）; 
 
  var  serializedProduct = JsonConvert.SerializeObject（tenantfilterList，Formatting.Indented）; 

这序列化为包含1个对象[{name：value}]的数组...注意[]差异表示数组

如果你向列表添加更多对象那么它将是序列化，如[{name：value}，{name：value2}，... etc]

在使用Get方法的立场我正在使用Post在Web api然后我修复了问题。



以下是我的代码



[HttpPost]

[Route（PopulateTenantGrid）]

  public   async 任务< list>< tenantlistitem>> GetAllTenant（TenantFilter过滤器）
 {
  var  result =  new 列表< tenantlistitem> （）; 
 尝试 
 {
  var  response =  await  TenantCore.LoadTenantGrid（filter）; 
  if （response！=  null ）
 {
 result = （列表与LT; tenantlistitem>）响应; 
 
} 
} 
  catch （System.Exception ex）
 {
 
 
} 
 返回结果; 
} 

i am calling web api through winform when i pass data to the class and call the function its show me the error.

Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'Properties.Model.Tenant.TenantListItem[]' because the type requires a JSON array (e.g. [1,2,3]) to deserialize correctly.

What I have tried:

[DataContract]
    public class TenantFilter
    {
        [DataMember]
        public string TenantName { get; set; }
        [DataMember]
        public long AreaID { get; set; }
    }

// my web api code 

 public async Task<list><tenantlistitem>> GetAllTenant(TenantFilter filter)
        {
            var result = new List<tenantlistitem>();
            try
            {
                var response = await TenantCore.LoadTenantGrid(filter);
                if (response != null)
                {
                    result = (List<tenantlistitem>)response;

                }
            }
            catch (System.Exception ex)
            {


            }
            return result;
        }
// calling through winform
private async Task<ienumerable><tenantlistitem>> PopulateTenantGridView()
        {
            var result = new List<tenantlistitem>();
            try
            {
                using (var client = new HttpClient())
                {
                    var name = txtName.Text;
                    var area = (cmbArea.SelectedValue == null ? 0 : (long)cmbArea.SelectedValue);

                    var tenantfilter = new TenantFilter
                    {
                        TenantName = name,
                        AreaID = area
                    };

                    var serializedProduct = JsonConvert.SerializeObject(tenantfilter,Formatting.Indented);
                    var content = new StringContent(serializedProduct, Encoding.UTF8, "application/json");
                    var response = await client.PostAsync("http://localhost:64456/api/Tenant/GetAllTenant/", content);

                    if (response.IsSuccessStatusCode)
                    {
                        var Jsonstring = await response.Content.ReadAsStringAsync();
                        var tenant = JsonConvert.DeserializeObject<tenantlistitem[]>(Jsonstring).ToList();
                        if (tenant != null)
                        {

                             result = tenant.Take(100).ToList();
                        }
                    }
                }

            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);

            }
            return result;
        }

解决方案

That is because, your JSON might be only like this,

{ /* document data here. */ }

But, the code that you are executing requires that your JSON document to be containing an array of the objects, which starts with [ and ends with ]. That is the error that you are encountering. Update the JSON document on the server so that your client-side code would work. If that doesn't work, then you would have to handle the problem yourself by using a try...catch block.

Read the following articles that I wrote and a bunch of my previous answers that would help you understand this concept even more:

From zero to hero in JSON with C#[^]
http://www.codeproject.com/Answers/1109587/How-to-deserialize-my-json-data-to-relevent-object#answer1[^]
http://www.codeproject.com/Answers/836988/how-to-remove-duplicate-records-in-a-json-file#answer2[^]
http://www.codeproject.com/Answers/879055/How-do-I-get-Ajax-to-read-my-json-string#answer1[^]
http://www.codeproject.com/Answers/828795/How-do-I-write-a-Csharp-program-to-read-json-data#answer2[^]

var tenantfilter = new TenantFilter
                    {
                        TenantName = name,
                        AreaID = area
                    };

                   var serializedProduct = JsonConvert.SerializeObject(tenantfilter,Formatting.Indented); 

this serializes to 1 object {"name":"value"} You can change the code to:

var tenantfilter = new TenantFilter
                    {
                        TenantName = name,
                        AreaID = area
                    };

var tenantFilterList = new List<tenantfilter>();
tenantFilterList.Add(tenantFilter);

                   var serializedProduct = JsonConvert.SerializeObject(tenantfilterList,Formatting.Indented);

this serializes to array which contains 1 object [ {"name":"value"} ] ...note the [ ] difference which indicates array
if you add more objects to list then it would be serialized such as [ {"name":"value"}, {"name":"value2"}, ...etc]

in stand of using Get Method I am using Post In Web api then i fixed the problem.

below is my code

[HttpPost]
[Route("PopulateTenantGrid")]

public async Task<list><tenantlistitem>> GetAllTenant(TenantFilter filter)
        {
            var result = new List<tenantlistitem>();
            try
            {
                var response = await TenantCore.LoadTenantGrid(filter);
                if (response != null)
                {
                    result = (List<tenantlistitem>)response;
 
                }
            }
            catch (System.Exception ex)
            {
 

            }
            return result;
        }

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