Hello Phong,

Thank you for posting in our community.

In order to address the root cause of your issue and provide you with better and more accurate support I will need an isolated working sample where the issue is reproducible. This will help me debug on my side and investigate further and find what is causing this behavior.

Additionally, a sample project illustrating Load on Demand functionality in igHierarchicalGrid could be found at the following link:

http://igniteui.com/hierarchical-grid/load-on-demand

Please have a look at this sample and if you still have any questions or concerns afterwards please fell free to get back to me with your isolated sample.

Looking forward to hearing from you.

In case that you have a field that you could use as a foreign key however you do not like to show in the grid you could hide it completely (even do not show it in the column chooser of Hiding feature) as following:

 GridColumnLayoutModel layout = new GridColumnLayoutModel();
 layout.AutoGenerateColumns = false;
 layout.Key = "Histories";
 layout.ForeignKey = "ProductID";
 layout.Columns.Add(new GridColumn() { HeaderText = "Something", Key = "Something", DataType = "string" });
 layout.Columns.Add(new GridColumn() { HeaderText = "ProductID", Key = "ProductID", DataType = "number" });
 layout.LoadOnDemand = false;
 layout.Features.Add(new GridHiding() { Inherit = true, ColumnSettings = new List<ColumnHidingSetting>() { 
 new ColumnHidingSetting(){ColumnKey = "ProductID",AllowHiding= false, Hidden=true }}
});

If there is no column in your underlying data source that you could use as foreign key you could use a custom implementation of load on demand. Infragistics GetData method used to retrieve the data for child layout requires this foreign key. This means that for if you choose to use a custom approach this method could not be used. Alternative approach could be to use WrappedGridResponse to send the data for your child layouts. WrappedGridResponse is a class that wraps the response in a particular way suitable for the igHierarchicalGrid. It takes data and grid model as parameters. For example in your GetChildren method you could do the following:

 public JsonResult GetChildren(string ajaxUpdateTarget, string path, string layout)
{
 if (ajaxUpdateTarget == "History")
{
 var histories = new List<ProductHistory>();
 histories.Add(new ProductHistory() { ProductID = 0, Something = "What" });
 GridModel gridModel = this.GetGridModel(ajaxUpdateTarget, 0);
 //gridModel.DataSource = histories.AsQueryable();
 WrappedGridResponse response;
 response = new WrappedGridResponse(histories, null);
 return Json(response, JsonRequestBehavior.AllowGet);
 // return gridModel.GetData(path, layout);
}
.
.

Please keep in mind that you will have to check the parent which is calling the method and you will have to filter the data by yourself in order to map corresponding data to its parent for each level. Additionally, GetData uses its internal techniques to handle all grid features enabled. Since every other approach is considered a custom implementation you will have to take care of how all the features are implemented manually.

I modified the provided sample with an illustration of my suggestion and I am attaching it for your reference. Please note that the data added for all child levels is the same because it has no foreign key defined and you will have your own relation to the parent and child to represent the correct data for each level.

I modified your sample

I hope you find my information helpful.

Please let me know if you need any further assistance with this matter.

Your requirement could be achieved by handling childGridCreating event. This event is fired before child grid is going to be created and allows the developer to override the child grid creation. In this event a reference to the parent row triggering the event could be retrieved. From the row you could get information about any cell that you would like and will help you uniquely identify your record. Afterwards, this data could be sent to the server(via the dataSource option) and there you could filter your data accordingly. For example:

//in Grid.cshtml
 $(function () {

 $("#grid-id-test").live("igchildgridcreating", function (evt, ui) {

 var parentRowId = ui.element.parents("tr[data-container='true']").prev().data("id"),
 parentGrid = ui.element.parents("table.ui-iggrid-table").data("igGrid"),
parentRowData = parentGrid.findRecordByKey(parentRowId);
 //every cell value could be retrieved using the column key
 var productNumber = parentRowData.ProductNumber;

 //afterwards this value could be send to the server via dataSource option
 ui.options.dataSource += "&productNumber=" + productNumber;

});
});
.
.
.
//in HomeController.cs
public JsonResult GetChildren(string ajaxUpdateTarget, string path, string layout, string productNumber)
        {
           
            if (ajaxUpdateTarget == "History" && productNumber=”AR-5381”)
            {
//filter your data according to your productNumber and add it to the        response
              WrappedGridResponse response;
              response = new WrappedGridResponse(histories, null);
              return Json(response, JsonRequestBehavior.AllowGet);
            }
            else
            {
 
//handle it according to you scenario
 
              
            }
        }
 

I believe this approach will help you achieve your requirement. However, we have a known issue logged in our internal system regarding firing of the childGridCreating event. This issue is fixed and currently being tested.

I have created a support case with an ID of CAS-154476-Q1J6Y4 for you and I will link it to our Development issue so you will get notification when it is released. You could view this case in your account in the Support Activity page.

Please let me know if you need any further assistance with this matter.