Is it possible to deserialize a json array with native DataContractJsonSerializer in a Windows Store App?
Example, from:
[{"groups":[{"name":"tom","vip":false},{"name":"sam","vip":true}]},{"groups":[{"name":"pam","vip":false},{"name":"mom","vip":true}]}]
To, anything roughly in the line of:
public class Group
{
public string name { get; set; }
public bool vip { get; set; }
}
[DataContract]
public class RootObject
{
[DataMember]
public List<Group> groups { get; set; }
}
So far, my attempts always resulted in a 'null' List or 'null' IEnumerable when doing it this way:
public static T deserializeJson<T>(string result)
{
DataContractJsonSerializer jsonSer = new DataContractJsonSerializer(typeof(T));
using (MemoryStream ms = new MemoryStream(Encoding.UTF8.GetBytes(result)))
{
ms.Position = 0;
return (T)jsonSer.ReadObject(ms);
}
}
All the things are correct. Just write these line to get the object array.
protected override void OnNavigatedTo(NavigationEventArgs e)
{
string json = #"[{""groups"":[{""name"":""tom"",""vip"":false},{""name"":""sam"",""vip"":true}]},{""groups"":[{""name"":""pam"",""vip"":false},{""name"":""mom"",""vip"":true}]}]";
var res = deserializeJson<RootObject[]>(json);
//OR
var res1 = deserializeJson<List<RootObject>>(json);
}
Related
I created a SqlMapper.TypeHandler to map a Customer object into a CreditAccount class as follows:
public class CustomerTypeHandler : SqlMapper.TypeHandler<Customer>
{
public override Customer Parse(object value)
{
throw new NotImplementedException();
}
public override void SetValue(IDbDataParameter parameter, Customer
value)
{
throw new NotImplementedException();
}
}
public class CreditAccount
{
public int AccountId { get; set; }
public Customer Customer{ get; set; }
}
public class Customer
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string MiddleName { get; set; }
}
When I connect to the DB and call a sproc, the CustomerTypeHandler Parse method is never called and my CreditAccount object is populated with the AccountId only. The Customer object is null.
I am calling it as follows:
public async Task<CreditAccount> GetCreditAccount(int accountId)
{
var sql = "MY PROC NAME HERE";
var parameters = new DynamicParameters();
parameters.Add("#AccountId", accountId);
SqlMapper.AddTypeHandler(new CustomerTypeHandler());
using (IDbConnection connection = Connection)
{
connection.Open();
var account = await connection.QueryFirstAsync<CreditAccount>(sql, parameters, commandType: CommandType.StoredProcedure);
return account;
}
}
}
I placed a breakpoint in the Parse method and it is never called.
The database connection works, and I am getting the AccountId.
My environment;
.NET Core 2.2
Dapper 1.50.5
The code is simple enough. I get not exceptions. Any ideas?
A year has passed and now there is no this error in Dapper 2.0.30.
I checked it on jsonb columns in Postgres.
using Dapper;
using Newtonsoft.Json;
using Npgsql;
using System;
using System.Data;
public class CreditAccount
{
public int AccountId { get; set; }
public Customer Customer { get; set; }
}
public class Customer
{
public string FirstName { get; set; }
public string LastName { get; set; }
public string MiddleName { get; set; }
}
public class CustomerJsonObjectTypeHandler : SqlMapper.TypeHandler<Customer>
{
public override void SetValue(IDbDataParameter parameter, Customer value)
{
parameter.Value = (value == null)
? (object)DBNull.Value
: JsonConvert.SerializeObject(value);
parameter.DbType = DbType.String;
}
public override Customer Parse(object value)
{
return JsonConvert.DeserializeObject<Customer>(value.ToString());
}
}
Example using this classes - all work fine.
static void Main(string[] args)
{
using (var connection = GetDefaultConnection())
{
connection.Open();
var customer = new Customer
{
FirstName = "Gaday",
LastName = "Ivanova",
MiddleName = "Petrovich"
};
var jsonData = JsonConvert.SerializeObject(customer);
var strQuery = $"SELECT 10500 as AccountId,'{jsonData}'::jsonb as Customer";
SqlMapper.AddTypeHandler(new CustomerJsonObjectTypeHandler());
try
{
var data = connection.QueryFirst<CreditAccount>(strQuery);
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
}
}
}
In my WebApi controller I have a few methods that return objects retrieved from a database which are serialized to Json. Everything works fine if a method serializes and returns only a single object, it fails when it tries to serialize a collection of objects.
This is my model class:
[Table("Athlete")]
public partial class Athlete
{
public Athlete()
{
Event = new HashSet<Event>();
User = new HashSet<User>();
}
[Required]
[StringLength(32)]
[DisplayName("First name")]
public string FirstName { get; set; }
[Required]
[StringLength(32)]
[DisplayName("Last name")]
public string LastName { get; set; }
[StringLength(32)]
[DisplayName("Sport")]
public string Sport { get; set; }
[Key]
[Column(TypeName = "numeric")]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public decimal Athlete_ID { get; set; }
[DataMember]
[Column(TypeName = "numeric")]
public decimal? Team_Team_ID { get; set; }
[NotMapped]
[DisplayName("Team")]
public string TeamName { get; set; }
[JsonIgnore]
public virtual Team Team { get; set; }
[JsonIgnore]
public virtual ICollection<Event> Event { get; set; }
[JsonIgnore]
public virtual ICollection<User> User { get; set; }
}
This works fine:
[HttpGet]
public IHttpActionResult GetById(int id)
{
var athlete = _db.Athlete
.Where(a => a.Athlete_ID == id)
.FirstOrDefault();
if (athlete != null)
{
return Json<Athlete>(athlete);
}
return NotFound();
}
The following method causes a serialization error (System.InvalidOperationException)
(The 'ObjectContent`1' type failed to serialize the response body for content type 'application/json; charset=utf-8'.)
The inner exception's message is "Self referencing loop detected for property 'ApplicationInstance' with type 'ASP.global_asax'. Path 'Request.Properties.MS_HttpContext.ApplicationInstance.Context'."
[HttpGet]
public IHttpActionResult GetAllAthletes()
{
var athletes = _db.Athlete.ToArray();
if (athletes != null)
{
return Ok(Json<IEnumerable<Athlete>>(athletes));
}
return NotFound();
}
I've already tried to change the serialization settings in WebApiConfig.cs like in this question but nothing has worked so far.
Any help would be appreciated.
I've managed to find a way to work-around this in a semi-elegant manner. I'm not completely happy with this but a man's gotta do what a man's gotta do.
In case anyone needs this in the future:
Create a class that implements the IHttpActionResult interface:
public class MyJsonResult : IHttpActionResult
{
object _value;
HttpRequestMessage _request;
public MyJsonResult(object value, HttpRequestMessage request)
{
_value = value;
_request = request;
}
public Task<HttpResponseMessage> ExecuteAsync(CancellationToken cancellationToken)
{
var response = new HttpResponseMessage()
{
Content = new StringContent(JsonConvert.SerializeObject(_value), Encoding.UTF8, "application/json"),
RequestMessage = _request,
StatusCode = HttpStatusCode.OK
};
return Task.FromResult(response);
}
}
Then use it in a following way:
[HttpGet]
public IHttpActionResult GetAllAthletes()
{
var athletes = _db.Athlete;
if (athletes != null)
{
return new MyJsonResult(athletes, Request);
}
return NotFound();
}
So that I can store the user's screen preferences, I have ScreenSettings entity that I want to retrieve when the program starts and save when the program ends.
For this reason I don't want to keep the context open.
I am wondering about the best way to do this.
I have tried the following
however I am not comfortable with the SaveSettings function because it deletes and re-adds the object.
How do I save changes to the object without actually replacing it?
namespace ClassLibrary1
{
using System.ComponentModel.DataAnnotations;
using System.Data.Entity;
//Domain Class
public class ScreenSetting
{
#region Properties
public int Id { get; set; }
[Required]
public int WindowLeft { get; set; }
[Required]
public int WindowTop { get; set; }
#endregion
}
// Context
public class Context : DbContext
{
#region Properties
public DbSet<ScreenSetting> ScreenSettings { get; set; }
#endregion
}
// UI
public class UI
{
#region Public Methods
// Get the settings object
public ScreenSetting GetSettings(int SettingsId)
{
var Db = new Context();
ScreenSetting settings = Db.ScreenSettings.Find(SettingsId);
if (settings == null)
{
settings = new ScreenSetting { Id = SettingsId, WindowTop = 100, WindowLeft = 100 };
Db.ScreenSettings.Add(settings);
}
Db.Dispose();
return settings;
}
// Save the settings object
public void SaveSettings(ScreenSetting settings)
{
var Db = new Context();
ScreenSetting oldSettings = Db.ScreenSettings.Find(settings.Id);
if (oldSettings == null)
{
Db.ScreenSettings.Add(settings);
}
else
{
Db.ScreenSettings.Remove(oldSettings);
Db.ScreenSettings.Add(settings);
}
Db.Dispose();
}
public void test()
{
ScreenSetting setting = this.GetSettings(1);
setting.WindowLeft = 500;
setting.WindowTop = 500;
this.SaveSettings(setting);
}
#endregion
#region Methods
private static void Main()
{
var o = new UI();
o.test();
}
#endregion
}
}
You ran into a common pattern, update or insert, which is so common that it's got a name: upsert. When a pattern is common, usually there also is a common solution.
In System.Data.Entity.Migrations there is an extension method AddOrUpdate that does exactly what you want:
public void SaveSettings(ScreenSetting settings)
{
using (var db = new Context())
{
db.ScreenSettings.AddOrUpdate(settings);
db.SaveChanges();
}
}
I'm trying to consume a RESTful JSON web service using WCF on the client side. The service is 3rd party, so I cannot make any changes to the server response.
The server is sending back a response that looks something like this when there's only one data point...
Single Data Point
{
"Data":
{
"MyPropertyA":"Value1",
"MyPropertyB":"Value2"
},
}
and something like this when there's more than one data point...
Multiple Data Points
{
"Data":
[
{
"MyPropertyA":"Value1",
"MyPropertyB":"Value2"
},
{
"MyPropertyA":"Value3",
"MyPropertyB":"Value4"
},
{
"MyPropertyA":"Value5",
"MyPropertyB":"Value6"
}
],
}
I have my service contract set up like this...
[ServiceContract]
public interface IRewardStreamService
{
[OperationContract]
[WebInvoke]
MyResponse GetMyStuff();
}
and a data point's data contract like this...
[DataContract]
public class MyData
{
[DataMember]
public string MyPropertyA { get; set; }
[DataMember]
public string MyPropertyB { get; set; }
}
and the only way I can get the single data point response to work is if I have a single instance property like this, but this does not parse the multiple data point response...
Response for Single Instance
[DataContract]
public class MyResponse
{
[DataMember]
public MyData Data { get; set; }
}
and the only way I can get the multiple data point response to work is if I have an array / list instance property like this, but this does not parse the single data point response...
Response for Multiple Instance
[DataContract]
public class MyResponse
{
[DataMember]
public IList<MyData> Data { get; set; }
}
I understand the issue is that the response is omitting the brackets when there's only one data point returned, but it seems that WCF doesn't play well with deserializing that syntax. Is there some way I can tell the DataContractJsonSerializer to allow single element arrays to not include brackets and then tell my service to use that serializer? Maybe a service behavior or something?
Any direction would be helpful.
You can use a custom message formatter to change the deserialization of the JSON into the data contract you want. In the code below, the data contract is defined to have a List<MyData>; if the response contains only one data point, it will "wrap" that into an array prior to passing to the deserializer, so it will work for all cases.
Notice that I used the JSON.NET library to do the JSON modification, but that's not a requirement (it just has a nice JSON DOM to work with the JSON document).
public class StackOverflow_12825062
{
[ServiceContract]
public class Service
{
[WebGet]
public Stream GetData(bool singleDataPoint)
{
string result;
if (singleDataPoint)
{
result = #"{
""Data"":
{
""MyPropertyA"":""Value1"",
""MyPropertyB"":""Value2""
},
}";
}
else
{
result = #"{
""Data"":
[
{
""MyPropertyA"":""Value1"",
""MyPropertyB"":""Value2""
},
{
""MyPropertyA"":""Value3"",
""MyPropertyB"":""Value4""
},
{
""MyPropertyA"":""Value5"",
""MyPropertyB"":""Value6""
}
],
} ";
}
WebOperationContext.Current.OutgoingResponse.ContentType = "application/json";
return new MemoryStream(Encoding.UTF8.GetBytes(result));
}
}
[DataContract]
public class MyData
{
[DataMember]
public string MyPropertyA { get; set; }
[DataMember]
public string MyPropertyB { get; set; }
}
[DataContract]
public class MyResponse
{
[DataMember]
public List<MyData> Data { get; set; }
public override string ToString()
{
return string.Format("MyResponse, Data.Length={0}", Data.Count);
}
}
[ServiceContract]
public interface ITest
{
[WebGet]
MyResponse GetData(bool singleDataPoint);
}
public class MyResponseSingleOrMultipleClientReplyFormatter : IClientMessageFormatter
{
IClientMessageFormatter original;
public MyResponseSingleOrMultipleClientReplyFormatter(IClientMessageFormatter original)
{
this.original = original;
}
public object DeserializeReply(Message message, object[] parameters)
{
WebBodyFormatMessageProperty messageFormat = (WebBodyFormatMessageProperty)message.Properties[WebBodyFormatMessageProperty.Name];
if (messageFormat.Format == WebContentFormat.Json)
{
MemoryStream ms = new MemoryStream();
XmlDictionaryWriter jsonWriter = JsonReaderWriterFactory.CreateJsonWriter(ms);
message.WriteMessage(jsonWriter);
jsonWriter.Flush();
string json = Encoding.UTF8.GetString(ms.ToArray());
JObject root = JObject.Parse(json);
JToken data = root["Data"];
if (data != null)
{
if (data.Type == JTokenType.Object)
{
// single case, let's wrap it in an array
root["Data"] = new JArray(data);
}
}
// Now we need to recreate the message
ms = new MemoryStream(Encoding.UTF8.GetBytes(root.ToString(Newtonsoft.Json.Formatting.None)));
XmlDictionaryReader jsonReader = JsonReaderWriterFactory.CreateJsonReader(ms, XmlDictionaryReaderQuotas.Max);
Message newMessage = Message.CreateMessage(MessageVersion.None, null, jsonReader);
newMessage.Headers.CopyHeadersFrom(message);
newMessage.Properties.CopyProperties(message.Properties);
message = newMessage;
}
return this.original.DeserializeReply(message, parameters);
}
public Message SerializeRequest(MessageVersion messageVersion, object[] parameters)
{
throw new NotSupportedException("This formatter only supports deserializing reply messages");
}
}
public class MyWebHttpBehavior : WebHttpBehavior
{
protected override IClientMessageFormatter GetReplyClientFormatter(OperationDescription operationDescription, ServiceEndpoint endpoint)
{
IClientMessageFormatter result = base.GetReplyClientFormatter(operationDescription, endpoint);
if (operationDescription.Messages[1].Body.ReturnValue.Type == typeof(MyResponse))
{
return new MyResponseSingleOrMultipleClientReplyFormatter(result);
}
else
{
return result;
}
}
}
public static void Test()
{
string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
WebServiceHost host = new WebServiceHost(typeof(Service), new Uri(baseAddress));
host.Open();
Console.WriteLine("Host opened");
ChannelFactory<ITest> factory = new ChannelFactory<ITest>(new WebHttpBinding(), new EndpointAddress(baseAddress));
factory.Endpoint.Behaviors.Add(new MyWebHttpBehavior());
ITest proxy = factory.CreateChannel();
Console.WriteLine(proxy.GetData(false));
Console.WriteLine(proxy.GetData(true));
Console.Write("Press ENTER to close the host");
((IClientChannel)proxy).Close();
factory.Close();
Console.ReadLine();
host.Close();
}
}
I don't know about using WCF so I'll change to Asp.Net WCF. Here is an article that will get you one the way
http://www.west-wind.com/weblog/posts/2012/Aug/30/Using-JSONNET-for-dynamic-JSON-parsing
I just can't figure out how to determine if it's an array or a single object. Here is a little code.
[TestMethod]
public void SingleObject()
{
using (var client = new HttpClient())
{
var result = client.GetStringAsync("http://localhost:8080/api/JSONTestOne");
string content = result.Result;
JObject jsonVal = JObject.Parse(content);
dynamic aFooObj = jsonVal;
Console.WriteLine(aFooObj.afoo.A);
}
}
[TestMethod]
public void ArrayWithObject()
{
using (var client = new HttpClient())
{
var result = client.GetStringAsync("http://localhost:8080/api/JSONTest");
string content = result.Result;
JObject jsonVal = JObject.Parse(content);
dynamic foos = jsonVal;
Console.WriteLine(foos[0].A);
}
}
I have a winform powerpacks datareapter control having a picture box. This is the code snippet from the classes.
DisplaySystemUsersControl.Designer.cs
this.picBoxUserImage.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D;
this.picBoxUserImage.DataBindings.Add(new System.Windows.Forms.Binding("Image", this.UserBindingSource, "User_Image", true));
this.picBoxUserImage.Location = new System.Drawing.Point(3, 3);
this.picBoxUserImage.Name = "picBoxUserImage";
this.picBoxUserImage.Size = new System.Drawing.Size(100, 93);
this.picBoxUserImage.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;
this.picBoxUserImage.TabIndex = 0;
this.picBoxUserImage.TabStop = false;
this.picBoxUserImage.Click += new System.EventHandler(this.picBoxUserImage_Click);
DisplaySystemUsersControl.cs
public DisplaySystemUsersControl()
{
InitializeComponent();
this.dataRepeaterAccounts.DataSource = this.UserBindingSource;
LoadAccountData();
}
private void LoadAccountData()
{
SystemUserBusinessClass oSystemUserBusinessClass = new SystemUserBusinessClass();
List<SystemUserEntity_Only_For_UI_Binding> obj = oSystemUserBusinessClass.GetSystemUsersForUI();
BindingSource tempUserBindingSource = (BindingSource)dataRepeaterAccounts.DataSource;
obj.ForEach(oSystemUserEntity_Only_For_UI_Binding => tempUserBindingSource.Add(oSystemUserEntity_Only_For_UI_Binding));
}
SystemUserEntity_Only_For_UI_Binding.cs
public class SystemUserEntity_Only_For_UI_Binding
{
public string User_Id { get; set; }
public string User_Name { get; set; }
public byte[] User_Image { get; set; }
}
User ID and User name is getting loaded. But Image is not getting loaded. SystemUserEntity_Only_For_UI_Binding.User_Image() is holding the image byte array.
Can anybody please tell me what is going wrong?
Your class should look something like this:
public class SystemUserEntity_Only_For_UI_Binding
{
public string User_Id { get; set; }
public string User_Name { get; set; }
public Image User_Image { get; set; }
}
The byte array needs to be translated into an image somewhere in your code:
using (MemoryStream ms = new MemoryStream(imgBytes)) {
this.User_Image = Image.FromStream(ms);
}
public void BindRepeater (DataSet dsObj)
{
pictureBox1.DataBindings.Clear();
pictureBox1.DataBindings.Add("ImageLocation", dt, "Photo");
dataRepeater1.DataSource = dsObj;
}