How to bind a variable with multiple types? LINQ

Question

I have been trying to bind a variable to WPF. I am using LINQ to get the data. The criteria is a unique int type and returns a single row of data that has 30 columns, of which there are several different types that need to be returned.

I am getting this error InvalidOperationException Class, but I can't figure out how to fix this?

This is what I have thus far,

internal class DatabaseQueries
   {
       public static IEnumerable<int> ModValues(DatabaseDataContext database, int staffNo)
            {
                return database.Staff_Mod_TBLs
                    .Where(staff => staff.Staff_No == staffNo).Cast<int>().ToList();

            }
   }

This is the code that set the variable,

int staffNumber = 192356;
            var modTblValue = DatabaseQueries.ModValues(sql, staffNumber);

And the XAML, (for some reason I can't post all the XAML, so this is an abbreviated snip of code.)

<DataGridTemplateColumn.CellTemplate>
                                    <DataTemplate>
                                        <TextBlock FontWeight="Normal" Text="{Binding Path=modTblValue, UpdateSourceTrigger=PropertyChanged}" />
                                    </DataTemplate>
                                </DataGridTemplateColumn.CellTemplate>

Bind your modTBlValue as a property. binding only works with properties. — Abin
– Abin, Commented Jun 30, 2016 at 14:19
@AbinMathew, I am not sure I follow? Sorry, still learning all this. — KyloRen
– KyloRen, Commented Jun 30, 2016 at 14:20
.Cast<int>() - where did you see that? Go and learn Select. Select, Where are pretty basic things, you can't use LINQ without knowing at least the basic constructs. — Ivan Stoev
– Ivan Stoev, Commented Jun 30, 2016 at 14:25
@IvanStoev, I believe that is called The process of learning something you don't already know. If I knew everything there was to know about LINQ, I am sure I would not be in the pickle. I am sure you can relate to when you wrote your first Hello world line of code? So you suggest using select? I followelled the error message that said I was missing a cast, that is why that is in there. I have literally searched dozens of pages to get where I am right now. — KyloRen
– KyloRen, Commented Jun 30, 2016 at 14:32

Abin · Accepted Answer · 2016-06-30 14:35:35Z

4

Create a property like below,

private string _modTblValue;
public string modTblValue 
    {
        get { return _modTblValue ; }
        set { modTblValue = value; NotifyPropertyChanged(); }
    }

Assign the value you get from DataBase to modTblValue

 modTblValue = DatabaseQueries.ModValues(sql, staffNumber);

Bind your property modTblValue with UI

<TextBlock FontWeight="Normal" Text="{Binding Path=modTblValue, UpdateSourceTrigger=PropertyChanged}" />

If you need a collection of your property to bind to a DataGrid then create a class which contain your Properties, and make a property of list of your class to bind as ItemSource of your DataGrid

Check this too.

edited Jun 30, 2016 at 14:35

answered Jun 30, 2016 at 14:23

Abin

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7 Comments

KyloRen Over a year ago

Thanks for the help, that clears up a part of all this that I was not doing correctly. But I still get an error with the query.

KyloRen Over a year ago

Yes, the LINQ query seems to be the problem. As Ivan stated in the comments, I need to use select. But, I can't get past the combine error when making one with select. InvalidOperationException Class error

Abin Over a year ago

Your return type is of IEnumerable<int> and consider reading this

KyloRen Over a year ago

I have been over that page many times, but I can't get the syntax correct to put the query into its own class???

KyloRen Over a year ago

Hey, I still can't get this syntax correct. I am going to mark this answer as the best answer. Thanks for the help.

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