Adding Serial# column programatically using DbContext

How can a serial# (auto-incremented integer) column be added on-the-fly, at the 0th index, to the Data/List returned by a data-fetching command such as follows:

var averages = dbContextObj.MinuteAverages
.Where(x => x.ID == selectedID &&
x.Timestamp >= startDate &&
x.Timestamp <= endDate)
.OrderBy(x => x.Timestamp).ToList();


This column along with actual data from MinuteAverages has to be added to a DataGridView and should be bound to corresponding retrieved records (as I assume it would) for sorting purposes.

MinuteAverages

DataGridView

1 Answer
1

First method

Create a ViewModel to extends the MinuteAverage properties
You can use Automapper to make your code easier

//remembet to add nuget and => using AutoMapper;
public class AveragesVM:MinuteAverage //inherit from your entity class retrieved from dbContextObj.MinuteAverages
{
public int Id{get;set;}
public AveragesVM:MinuteAverage(MinuteAverage minuteAverage)
{
var mapper= Mapper.Initialize(cfg => cfg.CreateMap<MinuteAverage,AveragesVM>());
return mapper.Map<AveragesVM>(minuteAverage);
}
}


And then, convert the MinuteAverage collection to an AveragesVM collection with the Id filled.

//remeber to add using System.Linq;

var averagesWithId = averages.Select(new AveragesVM(x))
.ForEach(x=> x.Id= averages.Indexof(x));


Second method

Also you can listen to databound event

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
GridViewRow row = e.Row;
row.Attributes["id"]=grdNews.DataKeys[e.Row.RowIndex].Value.ToString();
}
}


new AveragesVM(x)

x

GridView1_RowDataBound

var mapper= Mapper.Initialize...

Initialize()

void

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