How can I set column values to GridView Columns? - asp.net

Question

I have csv file like this:
I need to show this csv file with gridview. But I must change format like this:
I must select distinct just date and mount columns and use date values on gridview columns.
How can I use values of csv file for Gridview columns?

Answer 1

Assuming that reading the CSV file is not an issue and you have already something like a List<ClassName>, DataTable or List<string[]>. I'm presuming that it's a List<String[]> where the first "column" is Date, the second Mount and the last % in my following approach.
You need real DateTimes and ints to be able to sum percents by date:
var formatProvider = new CultureInfo("de-DE"); // seems to be the correct format
var mountGroups = listOfStringArray
.Select(arr => new
{
Date = DateTime.Parse(arr[0].Trim(), formatProvider).Date,
Mount = arr[1].Trim(),
Percent = int.Parse(arr[2].Trim())
})
.GroupBy(x => x.Mount);
Now you have grouped by Mount, you just need to sum the percents for every day. You can use a DataTable as datasource for the GridView. Here's code that creates the table with the dynamic columns for every day:
var dataSource = new DataTable();
dataSource.Columns.Add("Mount");
var lastWeekColumns = Enumerable.Range(0, 7)
.Select(d => new DataColumn(DateTime.Today.AddDays(-6 + d).ToShortDateString(), typeof(int)))
.ToArray();
dataSource.Columns.AddRange(lastWeekColumns);
Following loop executes the LINQ query and fills the table:
foreach(var grp in mountGroups)
{
DataRow row = dataSource.Rows.Add();
row.SetField("Mount", grp.Key); // because: GroupBy(x => x.Mount);
foreach(DataColumn dayCol in lastWeekColumns)
{
DateTime day = DateTime.Parse(dayCol.ColumnName, formatProvider);
int sumPercent = grp.Where(x => x.Date == day)
.Select(x => x.Percent)
.DefaultIfEmpty(0) // fallback value for missing days
.Sum();
row.SetField(dayCol, sumPercent);
}
}
Now you just need to use it as datasource (AuthoGenerateColumns set to true)
grid.DataSource = dataSource;
grid.DataBind();