StrataFrame Forum » .NET Forums » General .NET Discussion » Need help decifering a concept...

Need help decifering a concept...

StarkMike — Fri, 11 Aug 2006 15:52:09 GMT

Can someone help me decifer this line of code? I saw it somewhere and have used it a couple of times but I'm not sure what the concept is called or why it works.

Me.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue)("LocationID").ToString

If this piece of code were to take up two lines this is what it would look like this

Dim row As DataRowView = Me.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue)
Messagebox.Show(row("LocationID").ToString)

I'm referring to the way I can butt the set of parenthesis together.

Thanks for the help. :cool:

RE: Need help decifering a concept...

StrataFrame Team — Fri, 11 Aug 2006 15:52:09 GMT

No problem :)

RE: Need help decifering a concept...

StarkMike — Fri, 11 Aug 2006 15:50:04 GMT

Thanks Ben! Good stuff!

RE: Need help decifering a concept...

StrataFrame Team — Fri, 11 Aug 2006 15:48:43 GMT

In CSharp, the indexer properties cannot use the property name, but instead, they use the square brackets, so it looks like this instead:

this.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue)["LocationID"].ToString();

RE: Need help decifering a concept...

StrataFrame Team — Fri, 11 Aug 2006 15:47:18 GMT

Hi Mike,

The reason you can butt the parenthasis together is because of the way the properties work. It is the same concept as that of chaining together a bunch of dots, like this:

Me.TextBox1.Text

The first dot tells the "Me" variable that we are accessing one of its properties. The second dot tells the TextBox that we are accessing one of its properties.

Now, there are special properties called "indexers." An indexer is a "default" property that allows you to leave off the property name because it is understood. So, When you execute the GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue) method, it returns an instance to a DataRowView. If you were to put a dot at the end of those parenthasis, you would be telling the DataRowView that you want to access it's properties. So, you could do this: Me.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue).Row which would return the DataRow wrapped by the DataRowView. So, we combine this with the indexer property of the DataRowView item, which accepts a column name and returns the value within the field. So, since the property is the indexer (its the "Item" propery), you can leave off the .PropetyName because it's understood. So, the parenthasis are butted together because the ".Item" is understood, and therefore, left off.

Me.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue)("LocationID").ToString()

Me.cboDivisions.Properties.GetDataSourceRowByKeyValue(Me.cboDivisions.EditValue).Item("LocationID").ToString()