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GridBlazor for ASP.NET Core MVC

Subgrids

Index

You can enable the subgrids support for your grid. Subgrids allows to view records for those tables that have a 1 to N relationship with the parent table of the main grid.

We asume that you already configured the parent grid and it's working as expected as described in the Quick start section.

We have to add a service method to get rows for subgrids. An example of this type of service is:

    public class OrderService
    {
        ...

        public ItemsDTO<OrderDetail> GetOrderDetailsGridRows(Action<IGridColumnCollection<OrderDetail>> columns, 
            object[] keys, QueryDictionary<StringValues> query)
        {
            int orderId;
            int.TryParse(keys[0].ToString(), out orderId);
            var repository = new OrderDetailsRepository(_context);
            var server = new GridServer<OrderDetail>(repository.GetForOrder(orderId), new QueryCollection(query),
                true, "orderDetailssGrid" + keys[0].ToString(), columns)
                    .Sortable()
                    .WithPaging(10)
                    .Filterable()
                    .WithMultipleFilters();

            // return items to displays
            var items = server.ItemsToDisplay;
            return items;
        }
    }

This service method is very similar to the one we used for the main grid. The only difference is that this one has a new parameter named keys. It is an array of strings with the names of required columns to find records for the subgrid. In our example this array has only one element for the OrderId field. We use it to get the subgrid rows calling the GetForOrder method from the repository.

Note that the grid name parameter we use must be unique for each subgrid. In this example we use the name "orderDetailsGrid" + keys[0].ToString().

We have to add the following elements on OnInitAsync method of the same razor page we used to render the main grid:

    protected override async Task OnInitAsync()
    {
        ...
        
        Action<IGridColumnCollection<OrderDetail>> orderDetailColumns = c =>
        {
            c.Add(o => o.OrderID);
            c.Add(o => o.ProductID);
            c.Add(o => o.Product.ProductName);
            c.Add(o => o.Quantity).Format("{0:F}");
            c.Add(o => o.UnitPrice).Format("{0:F}");
        };

        ...

        Func<object[], Task<ICGrid>> subGrids = async keys =>
        {
            var subGridQuery = new QueryDictionary<StringValues>();
            var subGridClient = new GridClient<OrderDetail>(q => orderService.GetOrderDetailsGridRows(orderDetailColumns, keys, q), 
                subGridQuery, false, "orderDetailsGrid" + keys[0].ToString(), orderDetailColumns, locale)
                    .SetRowCssClasses(item => item.Quantity > 10 ? "success" : string.Empty)
                    .Sortable()
                    .Filterable()
                    .WithMultipleFilters()
                    .WithGridItemsCount();

            await subGridClient.UpdateGrid();
            return subGridClient.Grid;
        };

    }

The new 2 elements are:

  • the column defintion for the subgrid
  • and a function to create the subgrids for each keys parameter. It's important to declare all variables needed by the contructor of the GridClient object inside the function block to avoid sharing parameters among subgrids.

Finally we have to modify the GridClient we used to create the main grid adding a SubGrid method:

    protected override async Task OnInitAsync()
    {
        ...

        var client = new GridClient<Order>(q => orderService.GetOrdersGridRows(orderColumns, q), query, false,
            "ordersGrid", orderColumns, locale)
            .SetRowCssClasses(item => item.Customer.IsVip ? "success" : string.Empty)
            .Sortable()
            .Filterable()
            .WithMultipleFilters()
            .Searchable(true, false)
            .WithGridItemsCount()
            .SubGrid(subGrids, "OrderID");

    }

SubGrid parameters

Parameter Type Description
subGrids Func<object[], Task> function that creates subgrids defined in the step before
keys params string[] variable number of strings with the names of required columns to find records for the subgrid

<- Render button, checkbox, etc. in a grid cell | Passing grid state as parameter ->

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