MVC Hierarchical grid - Load on demand - throwing Object reference error

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Singh
Points 205
Replied On: Fri, Apr 28 2017 11:24 AM Reply

Hi,

I am trying to use a hierarchical grid using MVC 5. I am suppose to have three levels of data in the grid - parent , child and grand child.

I am able to bind the parent but not the child using Load on demand from the controller.

--Model
public class ParentViewModel
{
  public int PId {get; set;}
  public string Name {get; set;}
  public ICollection ChildDetails
}


Public class ChildViewModel
{
  public int CId {get; set;}
  public int PId {get; set;}
  public int CData {get; set;}
}

--View
@model Infragistics.Web.Mvc.GridModel

(Html.Infragistics().Grid(Model))

--Controller

private GridModel GetGridModel()
{  

            GridModel model = new GridModel();
            model.AutoGenerateColumns = false;
            model.AutoCommit = true;
            model.PrimaryKey = "PId";
            model.AutoGenerateLayouts = false;
            model.ID = "igGrid";

            model.LoadOnDemand = true;

            model.Columns.Add(new GridColumn { Key = "PId", Hidden = true, DataType = "number" });
            model.Columns.Add(new GridColumn { Key = "Name", HeaderText = "Parent Name ", DataType = "string" });
            model.DataSourceUrl = (Url.Action("BindParentDetails"));
           

            GridColumnLayoutModel childModel = new GridColumnLayoutModel();
            childModel.Key = "ChildDetails";
            childModel.PrimaryKey = "PID";
            childModel.ForeignKey = "CId";
            childModel.AutoGenerateColumns = false;
            childModel.Columns.Add(new GridColumn { Key = "CId", HeaderText = "Child ID", DataType = "number" });
            childModel.Columns.Add(new GridColumn { Key = "CData", HeaderText = "Child Data", DataType = "number" });
            childModel.DataSourceUrl = Url.Action("BindChildDetails");

            model.ColumnLayouts.Add(childModel);
            
            return model;
}


        public JsonResult BindParentDetails()
        {
            GridModel rModel = GetGridModel();

            var p = _service.GetPDetails();

            rModel.DataSource = p.AsQueryable();
            var res = rModel.GetData();
            return res;
        }

        public JsonResult BindChildDetails(string path, string layout)
        {
            var pid = path.Substring(path.LastIndexOf(':') + 1);


            GridModel grd = GetGridModel();

            var p = _service.GetChildDetails(pId);
            grd.DataSource = p.AsQueryable();
            var res = grd.GetData(path, layout);
            return res;
        }

When I run the solution it binds the parent grid correctly. On clicking the + icon it goes into BindChildDetails function and breaks on:

var res = grd.GetData(path, layout);

An exception of type 'System.NullReferenceException' occurred in Infragistics.Web.Mvc.dll but was not handled in user code

Additional information: Object reference not set to an instance of an object.

It has correct values in path and layout

grd.DataSource  is set correctly with the data from the DB.

The version of Infragistics.Web.Mvc we are using is 5.16.2.2040

Can anyone please help me with this?

  • Post Points: 20

All Replies

Singh
Points 205
Replied On: Tue, May 16 2017 12:48 PM Reply

Hi Mike,

Thanks for your reply. I will give this a try.

What do I need to do for sorting?

Regards

S

  • Post Points: 20
[Infragistics]Mike P
Points 23,565
Infragistics Employee
Replied On: Tue, May 16 2017 4:48 PM Reply

Hello Singh,

For sorting you would have to handle it in the same way of getting the info out of the request and using that to return the data you want in the order you want. Same for filtering. When you use load on demand in MVC you are responsible for returning the data. Note with sorting and filtering the key will be unique for each column.

Sincerely,
Mike P.
Software Developer
Infragistics, Inc.
www.infragistics.com

  • Post Points: 20
Singh
Points 205
Replied On: Wed, May 17 2017 10:51 AM Reply

Thanks Mike.

Can you please send me some links regarding sorting, paging and coloring the grid or a working example so it will be helpful.

Regarding your question:

What would be the reason you would be unable to save rows? You mean like they fail validation?

It is the requirement that if I there is a newer version of the data exists in the DB then I will not save the data therefore I would want to refresh the grid with the new data and color the row which wasn't saved.

What are the functions or property exposed by the grid to maintain the state?

Again if there are any links it will be really helpful

Regards

S

  • Post Points: 20
[Infragistics]Mike P
Points 23,565
Infragistics Employee
Replied On: Wed, May 17 2017 11:54 AM Reply

Hello Singh,

Concerning paging and sorting, here is the documentation we have:

Paging:
https://www.igniteui.com/help/iggrid-paging

http://www.igniteui.com/help/api/2016.2/ui.iggridpaging

Sorting:
https://www.igniteui.com/help/iggrid-sorting-overview

http://www.igniteui.com/help/api/2016.2/ui.iggridsorting

There isn’t specific documentation on how this behaviors interact with load on demand and as I said if you want them to be done remotely you will have to go through the request find the key you need and check if that key exists and then what the request param is for that key.

For adding styles to rows you would use jQuery’s addClass:
https://api.jquery.com/addclass/

https://www.igniteui.com/help/ighierarchicalgrid-styling-and-theming

For saving the state of the grid you would have to use the API methods to get the state of the grid to save it:
http://www.igniteui.com/help/api/2016.2/ui.ighierarchicalgrid

http://www.igniteui.com/help/api/2016.2/ui.iggrid_hg

Sincerely,
Mike P.
Software Developer
Infragistics, Inc.
www.infragistics.com

  • Post Points: 20
Singh
Points 205
Replied On: Thu, Jun 1 2017 7:50 AM Reply

Hi Mike,

Thanks for your reply above. I am still trying to do sorting in the grand child level but it doesn't seem to be working.

In Request.Params do not have any property related to sorting. I am trying to access Request.Params in my  BindGrandChildDetails(string path, string layout) method.

Can you send me any working example for this please?

Also I am trying to use Infragistics Datepicker in one of my pages like below:

in cshtml

@(Html.Infragistics().DatePicker()

.ID("Date")

.ButtonType(TextEditorButtonType.DropDown)

.AddClientEvent("valueChanged", "onChangeDate")

.Value(@ViewBag.Date)

.Render())

 and in script:

$("#Date").igDatePicker({

value: new Date(y, m, d),

dateDisplayFormat: "dd/MM/yyyy",

minValue : new Date(y -1 , m, d)

});

I am able to select date but when I hover over the dropdown of the datepicker it clears the textbox which had date in it but when I hover out it shows the date.

Can I remove this property to hide the date on hovering over the dropdown arrow?

Regards

S

  • Post Points: 20
[Infragistics]Mike P
Points 23,565
Infragistics Employee
Replied On: Thu, Jun 8 2017 10:52 AM Reply

Hello Singh,

What are you looking for when you search the params? As I mentioned sorting is unique for each column say for example you have a column called “QuatityPerUnit” the param key would look like the following: "sort(QuantityPerUnit)"

Concerning the behavior you are seeing with the igDatePicker I am unable to reproduce this behavior. Do you have a sample that demonstrates the behavior?

Sincerely,
Mike P.
Software Developer
Infragistics, Inc.
www.infragistics.com

  • Post Points: 5
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