Multiple usercontrols with different data injected showing same data

Question

Working on a page where I create new instances of a usercontrol I wrote, based on data. I pass in filtered data to the user control using constructor injection. However, when the user controls render, only the last set of data injected in is rendered for all user controls. It appears I'm referencing the same instance rather than creating a new, independent one. Ideas?

 protected void Page_Init(object sender, EventArgs e)
        {
            var data = <my data comes from here>;
            var yearsInData = data.OrderByDescending(x=>x.Year).Select(x => x.Year).Distinct();

            foreach(var year in yearsInData)
            {
                var employers = data.OrderBy(x=>x.EmployerName).Where(x => x.Year == year).Select(x => x.EmployerName).Distinct();
                foreach (var employer in employers)
                {
                    var eob = data.Where(x => x.Year == year).Where(x => x.EmployerName == employer);
                    if (eob.Count() > 0)
                    {
                        var ctl = LoadControl(@"~\Shared\Controls\AnnualEOBControl.ascx", eob);
                        pnlMain.Controls.Add(ctl);
                    }
                }
            }
        }

Here is the LoadControl method:

private UserControl LoadControl(string userControlPath, params object[] constructorParameters)
        {
            var constParamTypes = new List<Type>();
            foreach (var constParam in constructorParameters)
            {
                constParamTypes.Add(constParam.GetType());
            }

            var ctl = Page.LoadControl(userControlPath) as UserControl;

            // Find the relevant constructor
            if (ctl != null)
            {
                var constructor = ctl.GetType().BaseType.GetConstructor(constParamTypes.ToArray());

                // And then call the relevant constructor
                if (constructor == null)
                {
                    throw new MemberAccessException("The requested constructor was not found on : " + ctl.GetType().BaseType);
                }
                constructor.Invoke(ctl, constructorParameters);
            }

            // Finally return the fully initialized UC
            return ctl;
        }

score 0 · Accepted Answer · edited May 23 '17 at 12:04

It smells like a closure issue. My hunch is eob is merely being reassigned a value during each iteration as opposed to recreated. Since your controls all reference eob as opposed to the data returned by eob, they would all use the same value when it's time to render.

What does your LoadControl overload look like? I read through the article you referenced, but I'd like to see what you did, specifically. I wonder if simply reassigning values from eob to a variable declared inside your LoadControl method would get you over the hump. Force the controls to use a variable from a tighter scope so they can't physically see each other's arguments.

Edit: Found an SO reference on the topic: What are 'closures' in .NET?

Give this a whirl:

private UserControl LoadControl(string userControlPath, params object[] constructorParameters)
    {
        var constParamTypes = new List<Type>();
        foreach (var constParam in constructorParameters)
        {
            constParamTypes.Add(constParam.GetType());
        }

        var ctl = Page.LoadControl(userControlPath) as UserControl;

        // Find the relevant constructor
        if (ctl != null)
        {
            var constructor = ctl.GetType().BaseType.GetConstructor(constParamTypes.ToArray());

            // And then call the relevant constructor
            if (constructor == null)
            {
                throw new MemberAccessException("The requested constructor was not found on : " + ctl.GetType().BaseType);
            }

            // constructor.Invoke(ctl, constructorParameters);
            object[] cp = constructorParameters;
            constructor.Invoke(ctl, cp);
        }

        // Finally return the fully initialized UC
        return ctl;
    }

It occurs to me that it might be a little cleaner to just call .ToArray() when you're feeding LoadControl. Same effect. — Pete M, Apr 11 '11 at 18:00
Try the .ToArray() approach. I am admittedly not a closure expert, but I can't shake the notion that this is what's going on. — Pete M, Apr 11 '11 at 18:46

score 0 · Answer 2 · answered Apr 11 '11 at 17:15

0

If I had this issue and there was a base class I could instrument and a way to produce a trace of some kind without too much trouble, I'd

put a const instance member Guid and a DateTime, both initializes it in the constructor
put a few ms sleep between separate calls to the constructor so the timestamps

I'm just thinking that might give a hint as to what's going on and lead to the root of it.

answered Apr 11 '11 at 17:15

Aaron Anodide

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Did that. I passed in DateTime.Now.Ticks in the constructor and did a Response.Write. All entries where unique. EOB data was unique also. However the grid that I'm using to display renders only last set of data sent it. I even set the grid data source to the data passed in immediately. hmmm – Bill Martin Apr 11 '11 at 18:52
maybe you marked a field static and didn't mean to? or maybe it's some wierd linq thing? (tack .ToList() on the end...) - and i'm outta ideas... good luck :) – Aaron Anodide Apr 11 '11 at 19:05

Multiple usercontrols with different data injected showing same data

2 Answers2