Convert the results of IQueryable to a string to display in a textbox

Question

Using C#, WPF, .NET 4.5 In my program, I am trying to populate the value of a TextBox from a database. The value is obtained by a LINQ statement. I've tried all different things such as To.String() and Console.WriteLine() etc. If you can figure out a way to make this work that would be awesome, if you can find a better way to select the data and display it, i would be interested in that as well. C# Code:

private AuroraEntities auroraContext = null;    
private void LoadTB()
    { 
     this.auroraContext = new AuroraEntities();
     ObjectQuery<Inventory> inventories = auroraContext.Inventories;
     string name = ingNameCB.SelectedValue.ToString();  
     var queryResult = (from q in inventories
                        where q.InventoryName == name                          
                        select q);

    textBox1.DataContext = queryResult.ToString();
    }

XAML:

<TextBox Height="23" HorizontalAlignment="Left" Margin="70,186,0,0" Name="textBox1" VerticalAlignment="Top" Width="120" Text="{Binding Path=InventoryName, Mode=TwoWay}"

thanks!

score 4 · Accepted Answer · answered Aug 03 '13 at 19:56

Are you expecting a single result? If so, use First, or Single, or FirstOrDefault to obtain a single Inventory item (which of these options is most appropriate will depend on your situation). However, you will then have an Inventory item, an Inventory.ToString() may well not give you what you want either.

What are you trying to display from the inventory? Its name? Its description? Perhaps a combination? You should think about that very carefully - once you've decided what you're actually trying to achieve, writing the code for it is likely to be quite simple.

If your query could return multiple results, you've got even more to think about. Does it even make sense to have a single textbox? Perhaps you should be populating a table of some kind?

thanks for the tip. I would be returning only a single instance of InventoryName from the database. Eventually this would be bound to a Combobox, and changing that would populate the various TextBoxes associated with each column in the table, but this definately got me on my way and it is populating with a value now! Thanks for the fast response! — Joe K, Aug 03 '13 at 20:49

score 3 · Answer 2 · answered Aug 03 '13 at 19:59

3

Something like this:

(from q in inventories
 where q.InventoryName == name                          
 select q).FirstOrDefault().InventoryName;

You need also to check if FirstOrDefault() is not null

answered Aug 03 '13 at 19:59

Daniele

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Watch out for the possible null exception if the query resulted in no results. – Steven V Aug 03 '13 at 20:00

score 1 · Answer 3 · answered Aug 03 '13 at 20:02

1

Hi you can try it like this

var result = queryResult.FirstOrDefault();
textBox1.Text=result==null ? string.Empty :result.InventoryName;

I think there is no point of doing binding if your InventoryName dont fire NotifyPropertyChanged so its better you directly assign Text instead of DataContext

answered Aug 03 '13 at 20:02

yo chauhan

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Eventually i will be doing databinding to comboboxes, but that is a way down the road. Thanks for the help! – Joe K Aug 03 '13 at 20:50

Convert the results of IQueryable to a string to display in a textbox

3 Answers3