如何在C#中的linq的选择中放置条件

Question

I want to select values from LINQ

but these values depend on another control in my windows form in C#

Here is my code

var lstInfo = grdBreakDown.Rows.Cast<DataGridViewRow>()
    .Where(x => !x.IsNewRow)
    .Select(x => (tag: x.Cells["tag"].Value.ToString(), Scheme: x.Cells["Scheme"].Value.ToString(), Value: x.Cells["Value"].Value.ToString()))
    .Distinct()
    .ToList();

lvwInfo.Items.AddRange( lstInfo
    .Select(x => new ListViewItem(new string[] { x.tag, x.Scheme, x.Value }))
    .ToArray()
);

This code works perfectly and displays all Schemes something like this

    Tag  Scheme  Value
    Red  Master  88
    Red  Master  14
    Red  Admin   39
    Red  Admin   31
    Blue Master  91
    Blue Master  10
    Blue Admin   54
    Blue Admin   04

But I want to make a few changes and only displays Schemes & Value when a checkbox in the windows form is ticked and if not ticked just display empty string

something like this

    .Select(x => (
        tag: x.Cells["tag"].Value.ToString(),
        Scheme:
            if(
                (!cbxMaster.checked &&  x.Cells["Scheme"].Value.ToString() == "Master")
                ||
                (!cbxAdmin.checked &&  x.Cells["Scheme"].Value.ToString() == "Admin"), "", x.Cells["Scheme"].Value.ToString()
            ),
        Value:
            if((!cbxMaster.checked &&  x.Cells["Scheme"].Value.ToString() == "Master")
                ||
                (!cbxAdmin.checked &&  x.Cells["Scheme"].Value.ToString() == "Admin"), "", x.Cells["Value"].Value.ToString()
            )
    )

So if Master ticked an Admin is not ticked

output will be like this

    Tag  Scheme  Value
    Red  Master  88
    Red  Master  14
    Red     
    Blue Master  91
    Blue Master  10
    Blue 

but this is not working.

how to do that with linq?

Answer 1

To modify what you have selected, you have to browse through the entire selection.

var lstInfo = grdBreakDown.Rows.Cast<DataGridViewRow>()
                               .Where(x => !x.IsNewRow)
                               .Select(x => (tag: x.Cells["tag"].Value.ToString(), Scheme: x.Cells["Scheme"].Value.ToString(), Value: x.Cells["Value"].Value.ToString()))
                               .Distinct()
                               .ToList()
                               .foreach (elem=>{
                                     if(elem.Sheme.equals("Admin")){
                                         elem.Sheme="";
                                         elem.value="";}
                                });

Answer 2

Why not try a conditional operator for the value you are searching for?

.Where(x => x.Cells["Scheme"].Value.ToString() == ((checked) ? "Master" : "Admin") )

Checked could be a bollean value or whether the tickbox is ticked. I think this will work

Answer 3

Define the problem

You could translate that to: Get the values of the Admin and/or Master rows if the corresponding CheckBox controls are checked. Otherwise, get their distinct tags.

Thus:

private void PopulateListView()
{
    // Local function...
    (string tag, string scheme, string value) GetItems(DataGridViewRow row) =>
        (chkAdmin.Checked && row.Cells["scheme"].Value.ToString() == "Admin") ||
        (chkMaster.Checked && row.Cells["scheme"].Value.ToString() == "Master")
        ? (
        row.Cells["tag"].Value.ToString(),
        row.Cells["scheme"].Value.ToString(),
        row.Cells["value"].Value.ToString())
        : (
        row.Cells["tag"].Value.ToString(),
        string.Empty,
        string.Empty);

    var lstInfo = dgv.Rows.Cast<DataGridViewRow>()
        .Where(x => !x.IsNewRow)
        .Select(x => GetItems(x))
        .Distinct()
        .Select(x => new[] { x.tag, x.scheme, x.value });

    lvwInfo.Items.Clear();
    lvwInfo.Items.AddRange(lstInfo.Select(x => new ListViewItem(x)).ToArray());
}