Grid Grouping, group headers, footers

Grouping can be enabled or disabled for the whole grid by using the .Groupable(bool) and can be set for each column by setting the Column.Groupable

Column.Group - defines initial column grouped state
Column.GroupRank - group rank for this column
Column.GroupRemovable - (default is true) if set to false grouped column won't have the remove group button
.ShowGroupedColumn - default true, show grouped columns
GridModelBuilder.MakeHeader - defines a function for creating the GroupHeader
GridModelBuilder.MakeFooter - function for creating a group footer

GridDemo/GroupingContent.cshtml

@model AweCoreDemo.ViewModels.Input.GridDemoGroupingCfgInput

@(Html.Awe().Grid("GroupingGrid")
      .Columns(
          new Column{Bind = "Id", Width = 75},
          new Column{Bind = "Person", Group = Model.PersonGrouped, 
              GroupRemovable = Model.PersonRem, Groupable = Model.PersonGroupable, GroupRank = Model.PersonRank},
          new Column{Bind = "Food.Name",  Group = Model.FoodGrouped, 
              GroupRemovable = Model.FoodRem, Groupable = Model.FoodGroupable, GroupRank = Model.FoodRank},
          new Column{Bind = "Date", Width = 180},
          new Column{Bind = "Price", Width = 80},
          new Column{Bind = "Location"},
          new Column{Bind = "Chef.FirstName,Chef.LastName", Prop = "ChefName", Header = "Chef", FooterClientFormat = ".(ChefCount)"}
      )
      .Height(450)
      .ShowGroupBar(Model.ShowGroupBar)
      .Groupable(Model.Groupable)
      .ShowGroupedColumn(Model.ShowGroupedColumn)
      .Parameter("collapsed", Model.Collapsed)
      .Url(Url.Action("GetItems","GroupingGrid")))

Demos/Grid/GroupingGridController.cs

public class GroupingGridController : Controller
{
    public IActionResult GetItems(GridParams g, bool collapsed)
    {
        var query = Db.Lunches.AsQueryable();

        // passing MakeFooter and MakeHeader to customize header and add footer
        var gmb = new GridModelBuilder<Lunch>(query, g)
        {
            KeyProp = o => o.Id,
            Map = o => new
            {
                o.Id,
                o.Person,
                FoodName = o.Food.Name,
                Date = o.Date.ToShortDateString(),
                o.Price,
                o.Location,
                ChefName = o.Chef.FullName
            },
            MakeFooter = MakeFooter,
            MakeHeader = gpinf => MakeHeader(gpinf, collapsed)
        };

        return Json(gmb.Build());
    }

    private GroupHeader MakeHeader(GroupInfo<Lunch> g, bool collapsed)
    {
        // get first item in the group
        var first = g.Items.First();

        // get the grouped column value(s) for the first item
        var val = string.Join(" ", AweUtil.GetColumnValue(g.Column, first).Select(ToStr));

        return new GroupHeader
        {
            Content = string.Format(" {0} : {1} ( Count = {2}, Max Price = {3} )",
                g.Header,
                val,
                g.Items.Count(),
                g.Items.Max(o => o.Price)),
            Collapsed = collapsed
        };
    }

    private object MakeFooter(GroupInfo<Lunch> info)
    {
        // will add the word Total at the grid level footer (Level == 0)
        var pref = info.Level == 0 ? "Total " : "";

        return new
        {
            Food = pref + " count = " + info.Items.Count(),
            Location = info.Items.Select(o => o.Location).Distinct().Count() + " distinct locations",
            Date = pref + " max: " + info.Items.Max(o => o.Date).Date.ToShortDateString(),
            Price = info.Items.Sum(o => o.Price),
            ChefCount = info.Items.Select(o => o.Chef.Id).Distinct().Count() + " chefs"
        };
    }

    private static string ToStr(object o)
    {
        return o is DateTime ? ((DateTime)o).ToShortDateString() : o.ToString();
    }
}