I have been thinking a lot about how Typed DataSets are generated and was spelunking through the code again when it got me thinking. The Typed DataSet generator doesn't really generate the code based on the .xsd, but on the DataSet. It simply loads the .xsd into a DataSet then interrogates the DataSet directly for everything (tables, columns, relationships, constraints). So if the Typed DataSet Designer cannot handle something (like relationships *without* constraints, see below), but the DataSet schema allows it...simply create the DataSet and save the .xsd file to see what it produces! This gets around some fundamental problems with the designer. It does require you start looking and understanding .xsd, but it is a useful skill to have anyway...right?
So my first relevation was how to add unconstrained relationships (no foreign key constraint, simply a way to navigate the data). Since the designer does not allow this, I looked at the .xsd and found that the DataSet handles this with a schema annotation:
I have been reviewing a bunch of code that utilizes ADO.NET's DataAdapters. This code has been some samples that are on the Internet, some questions directly to http://wildermuth.com and others from DevelopMentor's .NET Mailing Lists. One thing I have noticed is that much of that code is opening the database connection before using the DataAdapter to fill a DataSet.
This does work, but there seems to be some confusion about how this should work. In fact, under the covers all DataAdapters open and close the database if it has not already been done. This is because the DataAdapter knows when to open and close the connection to the database to minimize the length of time that the precious resource (the connection) is actually open. This is what the code looks like that I've been reviewing:
Why is everyone so down on using DataSets in .NET Web Services? Sure, I’ll admit that using DataSets directly as Web Service parameters are indeed a problem. But why throw the baby out with the bath water?
For the uninitiated, DataSets are a problem as Web Service parameters because XML that is automatically generated as the parameter is a DiffGram of the DataSet. Unfortunately DiffGrams are simply not interop-friendly. At the end of the day the obvious use of DataSets in .NET Web Services are simply a bad idea.
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|Application Name||WilderBlog||Environment Name||Production|
|Application Ver||v4.0.30319||Runtime Framework||x86|
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|Operating System||Microsoft Windows 10.0.14393||Runtime Arch||X86|