Grouping not working

[eloyrubio]

When trying to do serverside grouping I get the following JS error:

kendo.all.js:69687 Uncaught TypeError: Cannot read property 'length' of undefined
    at init._rowsHtml (kendo.all.js:69687)
    at init._groupRowHtml (kendo.all.js:69772)
    at init._renderContent (kendo.all.js:70517)
    at init.refresh (kendo.all.js:70340)
    at init.e (jquery-3.1.1.min.js?v=HPMOWdIdSuVgr3FD9ZE-_MgiK8qk_MdQjrgCtfqp6U4:2)
    at init.trigger (kendo.all.js:164)
    at init._process (kendo.all.js:7994)
    at init.success (kendo.all.js:7690)
    at success (kendo.all.js:7581)
    at Object.n.success (kendo.all.js:6452)

That's the datasource:

 var dataSource = {
            schema:
            {
                data: "Data",
                total: "Total",
                aggregates: "Aggregates",
                groups: "Groups",
                errors: "Errors"
            },
            transport: {
                read: {
                    url: 'xxx',
                    dataType: 'json',
                    contentType: 'application/json; charset=utf-8',
                    type: 'POST'
                },
                parameterMap: function (data) {
                    return JSON.stringify(
                        {
                            dataSourceRequest: data                         
                        });
                }
            },
            pageSize: 50,
            serverPaging: true,
            serverFiltering: true,
            serverSorting: true,
            serverGrouping: true
        }

I'm using Kendo.DynamicLinqCore 3.1.1 and Telerik.UI.for.AspNet.Core 2020.3.1021. Am I missing something?

[dandrayan]

I encountered this as well when pulling data from a legacy WCF service. The error I'm seeing in my WCF service traces is: System.Runtime.Serialization.InvalidDataContractException: No set method for property 'Field' in type 'Kendo.DynamicLinqCore.GroupResult'.

To get around this, I changed the return type of my WCF method from DataSourceResult to string and used Newtonsoft.Json.JsonConvert.SerializeObject to generate the JSON instead of the built-in WCF serializer. I also had to create a custom Newtonsoft.Json.JsonConverter class to massage the GroupResult object into something that my Kendo grid could parse and display correctly:

public class GroupResultConverter : JsonConverter 
{
	public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) 
	{
		var typedValue = (GroupResult)value;
		var result = new {
			aggregates = typedValue.Aggregates ?? new object[0],
			field = typedValue.SelectorField,
			hasSubgroups = typedValue.HasSubgroups,
			items = typedValue.Items,
			total = typedValue.Count,
			value = typedValue.Value
		};
		serializer.Serialize(writer, result);
	}

	public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) 
	{
		throw new NotImplementedException();
	}

	public override bool CanConvert(Type objectType) 
	{
		return objectType == typeof(GroupResult);
	}
}

[linmasaki]

When trying to do serverside grouping I get the following JS error:

kendo.all.js:69687 Uncaught TypeError: Cannot read property 'length' of undefined
    at init._rowsHtml (kendo.all.js:69687)
    at init._groupRowHtml (kendo.all.js:69772)
    at init._renderContent (kendo.all.js:70517)
    at init.refresh (kendo.all.js:70340)
    at init.e (jquery-3.1.1.min.js?v=HPMOWdIdSuVgr3FD9ZE-_MgiK8qk_MdQjrgCtfqp6U4:2)
    at init.trigger (kendo.all.js:164)
    at init._process (kendo.all.js:7994)
    at init.success (kendo.all.js:7690)
    at success (kendo.all.js:7581)
    at Object.n.success (kendo.all.js:6452)

That's the datasource:

 var dataSource = {
            schema:
            {
                data: "Data",
                total: "Total",
                aggregates: "Aggregates",
                groups: "Groups",
                errors: "Errors"
            },
            transport: {
                read: {
                    url: 'xxx',
                    dataType: 'json',
                    contentType: 'application/json; charset=utf-8',
                    type: 'POST'
                },
                parameterMap: function (data) {
                    return JSON.stringify(
                        {
                            dataSourceRequest: data                         
                        });
                }
            },
            pageSize: 50,
            serverPaging: true,
            serverFiltering: true,
            serverSorting: true,
            serverGrouping: true
        }

I'm using Kendo.DynamicLinqCore 3.1.1 and Telerik.UI.for.AspNet.Core 2020.3.1021. Am I missing something?

This library is for Kendo UI for JQuery, so I didn't test it on Telerik.UI.for.AspNet.Core. I suggest you can check your server response data first.

[eloyrubio]

I managed to make it work by Replacing the DataMember by JsonPropertyName. More info here: https://github.com/dotnet/aspnetcore/issues/14158