One of the
main goals behind relational databases design is reduce/eliminate the amount of
duplicated data. In order to do that, they split the data into multiple tables
and relate them by FK. While this works really well in database terms, they
don’t when it comes to searching or loading data (In highly normalized database
we usually need a lot of JOINs)
Continuing
with an example that we were working on previous posts (products by category)
we can see this design lines in action.
The goal of
our report is allow the users to select a category, and based on that category,
fetch the corresponding list of products. The problem is, if we look at the
products table, the product's category is and ID (numeric), which is hard to remember and
does not make any sense on his own. In this kind of scenarios, we can use the
autocomplete control. This control will allows to the user to filter by
description (category name) or any field that make sense to him/her and pass to
the report engine the corresponding ID to filter the relational data (in this
case, the category ID).
To get an
autocomplete in our dialog, we need to define a class that looks something like
this:
* Annotations
are required because we are working with a "legacy database” wich does not
follow the NRapid conventions, more on this in future posts.
As you may
already guess, CategoryName is the field that we are going to use to provide
some sort of searching feature, and CategoryID is the field we will use to query
the database.
Ones this
class is done, we only need to add a property to the nested class “Dialog”
(seen in previous posts) and NRapid will take cares of the rest.
When
executing the report, you will see a textbox labeled “category”, pressing F2
will a show a list of categories, select one and confirm the dialog.
On the next
post, customizing autocompletes. Stay tuned!
You can get the source code of NRapid from here
And the sample app from here
The Northwind database is available from download at http://www.microsoft.com/en-us/download/details.aspx?id=23654
Comments
Post a Comment