Filter data using a drop down

Question

User251280784 posted

Hello peeeps

I have two tables with a many-to-many relationship. I want to filter the result set from table 1 table with the assigned entities of table 2. I can't seem to get the filter to work properly. Any help would be most appreciated.

Code below:

CONTROLLER:

== CONTROLLER ==

        [HttpPost]

        public ActionResult Index(string filterMarkets)

        {

            var asrs = from a in db.ASR

                       select a;

 

            var markets = from m in db.Market

                          select m;

 

            ViewBag.assignedMarkets = new SelectList(db.Market, "MarketID", "MarketName");

 

            if (!String.IsNullOrEmpty(filterMarkets))

            {

                asrs = asrs.Where(a => a.FullName.Contains(filterMarkets.ToString()));

            }

            else if (!String.IsNullOrEmpty(filterMarkets))

            {

                markets = markets.Where(m => m.MarketName.ToUpper().Contains(filterMarkets.ToUpper()));

 

            }

            return View(asrs.ToList());

        }

==========

== VIEW ==

                @using (Html.BeginForm())

                {

                    @Html.AntiForgeryToken()

                    @Html.DropDownList("assignedMarkets", ViewBag.MarketsList as SelectList, "-- Filter By Market --", new { @onchange = "this.form.submit();", @class = "btn btn-primary dropdown-toggle btn-sm", @value = "filterMarkets" })

                }

========

Answer 1

User475983607 posted

ViewBag.MarketsList is not assigned a value in the code snippet.  Please review and run your code through the Visual Studio debugger as the code has several logic errors.

https://docs.microsoft.com/en-us/visualstudio/debugger/navigating-through-code-with-the-debugger?view=vs-2017

public ActionResult Index(string filterMarkets)
{
	var asrs = from a in db.ASR
	select a;
	var markets = from m in db.Market
	select m;
	ViewBag.assignedMarkets = new SelectList(db.Market, "MarketID", "MarketName");
	if (!String.IsNullOrEmpty(filterMarkets))
	{
		asrs = asrs.Where(a => a.FullName.Contains(filterMarkets.ToString()));
	}
	else if (!String.IsNullOrEmpty(filterMarkets))
	{
		markets = markets.Where(m => m.MarketName.ToUpper().Contains(filterMarkets.ToUpper()));
	}
	return View(asrs.ToList());
}
==========
== VIEW ==
@using (Html.BeginForm())
{
	@Html.AntiForgeryToken()
	@Html.DropDownList("assignedMarkets", ViewBag.MarketsList as SelectList, "-- Filter By Market --", new { @onchange = "this.form.submit();", @class = "btn btn-primary dropdown-toggle btn-sm", @value = "filterMarkets" })
}

Answer 2

User-943250815 posted

Is your return correct? It always return asrs

public ActionResult Index(string filterMarkets) {
  var asrs = from a in db.ASR select a;
  var markets = from m in db.Market select m;
  ViewBag.assignedMarkets = new SelectList(db.Market, "MarketID", "MarketName");
  if (!String.IsNullOrEmpty(filterMarkets)) {
    asrs = asrs.Where(a => a.FullName.Contains(filterMarkets.ToString()));
  }
  else if (!String.IsNullOrEmpty(filterMarkets))
  {
  markets = markets.Where(m => m.MarketName.ToUpper().Contains(filterMarkets.ToUpper()));
  }
  return View(asrs.ToList());
}

Answer 3

User251280784 posted

It should return the asrs. However, the filter should return the filtered asrs results. If you think it should return something other than that, let me know. I am also going to look at the previous response, it mentioned logic errors, I'll see what that's about.

Answer 4

User1520731567 posted

Hi CarCancelo,

I want to filter the result set from table 1 table with the assigned entities of table 2. I can't seem to get the filter to work properly.

if (!String.IsNullOrEmpty(filterMarkets))
	{
		asrs = asrs.Where(a => a.FullName.Contains(filterMarkets.ToString())); //line1
	}
	else if (!String.IsNullOrEmpty(filterMarkets))
	{
		markets = markets.Where(m => m.MarketName.ToUpper().Contains(filterMarkets.ToUpper())); //line2
	}
	return View(asrs.ToList());

According to your code,this does have a logic error.

Both line1 and line2 will run,but you only return asrs so that it makes line2 invalid.

I know you would like to make line1 and line2 contact and filter the data between them.

And there may be duplicate data.

So,Since I do not know what is your source,I suggest you could combine use .Intersect(), . Except(),.Add(),.Distinct()...

They will help you handle data.

Best Regards.

Yuki Tao