2

I am returning this from server to JSON, a jquery data table but it returns error:

System.InvalidOperationException: A circular reference was detected while serializing an object of type 'System.Reflection.RuntimeModule'.
   at WebServices.himher.getUsers1(Int32 iDisplayLength, Int32 iDisplayStart, Int32 iSortCol_0, String sSortDir_0, String sSearch)

.cs code:

public void getUsers1(int iDisplayLength, int iDisplayStart, int iSortCol_0, string sSortDir_0, string sSearch)
{
    try
    {
        basicoperation bop = new basicoperation();
        DataTable dt;

        dt = bop.getUsers(iDisplayLength, iDisplayStart, iSortCol_0, sSortDir_0, sSearch); // fetching users

        dt.TableName = "usersDT1";

        //int iTotalRecords=0;
        //int iTotalDisplayRecords= 0;

        var retObj = new
        {
            iTotalRecords= 20,
            iTotalDisplayRecords= 10,
            aaData= dt
        };

        //string json = JsonConvert.SerializeObject(dt);

        JavaScriptSerializer js = new JavaScriptSerializer();

        Context.Response.Write(js.Serialize(retObj));
    }
    catch (Exception ex)
    {

        throw ex;
    }
}
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1
  • The exception message is pretty clear. You have a circular reference in your data models which cannot be serialized. Make a DTO an select only data that should reach the view, not the whole data table Commented Aug 9, 2017 at 6:21

3 Answers 3

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5

The problem is that your retObj contains a DataTable, this cannot be serialised to JSON as is, as it has circular references inside it.

This article shows different ways to serialise the datatable;

http://www.c-sharpcorner.com/UploadFile/9bff34/3-ways-to-convert-datatable-to-json-string-in-Asp-Net-C-Sharp/

My preferred is probably the last way

using Newtonsoft.JSON;  

public string DataTableToJSONWithJSONNet(DataTable table) {  
   string JSONString=string.Empty;  
   JSONString = JSONConvert.SerializeObject(table);  
   return JSONString;  
}
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0

It's pretty clear you have a circular reference here in your code aaData= dt.
You can use below code to solve this issue,

JsonConvert.SerializeObject(retObj, Formatting.None, 
                    new JsonSerializerSettings {ReferenceLoopHandling = 
                                          ReferenceLoopHandling.Ignore});
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0

An easier alternative to solve this problem is to return an string, and format that string to json with JavaScriptSerializer.

public string GetEntityInJson()
{
   JavaScriptSerializer j = new JavaScriptSerializer();
   var entityList = dataContext.Entitites.Select(x => new { ID = x.ID, AnotherAttribute = x.AnotherAttribute });
   return j.Serialize(entityList );
}

It is important the "Select" part, which choose the properties you want in your view. Some object have a reference for the parent. If you do not choose the attributes, the circular reference may appear, if you just take the tables as a whole.

Do not do this:

public string GetEntityInJson()
{
   JavaScriptSerializer j = new JavaScriptSerializer();
   var entityList = dataContext.Entitites.toList();
   return j.Serialize(entityList );
}

Do this instead if you don't want the whole table: 

public string GetEntityInJson()
{
   JavaScriptSerializer j = new JavaScriptSerializer();
   var entityList = dataContext.Entitites.Select(x => new { ID = x.ID, AnotherAttribute = x.AnotherAttribute });
   return j.Serialize(entityList );
}

This helps render a view with less data, just with the attributes you need, and makes your web run faster.

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