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.NET Forum / Windows Forms / WinForm Data Binding / January 2007Designer creating duplicate DataRelation
Hi I've created a typed DataSet called MembershipDataSet. MembershipDataSet contains a baked-in DataRelation between two tables which gets created in the constructor and added to the base class DataRelationCollection. In VS forms I drag the MembershipDataSet component onto the form. Then I add a binding source which uses the MembershipDataSet instance as its DataSource and the master table name as the DataMember. I then drag a DataGridView onto the form and set the DataSource property to the binding source. Then I add a second binding source and set the DataSource to the first binding source. The DataMember is set to the name of the DataRelation which is listed in the Properties window. I then drag another DataGridView for the child table and set its DataSource to the second binding source instance. So far, so good. When I run the application I get a 'DuplicateNameException' because the designer has created and added a new DataRelation with the same name as the MembershipDataSet instance existing relationship. Catch 22 - If I don't create the DataRelation in the MembershipDataSet then I won't see it in the designer, in which case I'd have to create it by hand which, defeats the purpose of using the visual designer to work with databinding. I realise I could do the necessary to get everything working just as I'd like it to by hand, but I'm curious as to why it tries to create the DataRelation even though one already exists. Any ideas where it's/I'm going wrong? TIA Glenn Hi, > Hi > [quoted text clipped - 28 lines] > > Any ideas where it's/I'm going wrong? Not really, seems very strange. AFAIK the designer can't/won't add relations to a typed DataSet relational binding or not. I also tried a similar setup to what you described and can't reproduce the problem. When you get the Exception, does the stack trace (debug) doesn't provide any meaningfull info (like where it originated )? How do you know it's the designer that's adding the relation ? Did you look at the designer generated code (InitializeComponent inside the designer.cs file) ? HTH, Greetings > TIA > > Glenn > Hi, > [quoted text clipped - 36 lines] > relations to a typed DataSet relational binding or not. I also tried > a similar setup to what you described and can't reproduce the problem. Yes, the designer *does* do this if the relationship is defined in your database schema. Create a strongly typed dataset with both the Customers and Orders tables from Northwind in it; you will see the relation between them drawn automatically. My question for OP is this: is the MembershipDataSet's "baked-in" relation coming from the designer-generated code? Or did he add it programmatically or to the DataSet in the designer? Is there a datarelation defined in the database like a foreign key? If there is a foreign key, then there is a data relation. Robin S. Responses inline... >> Hi, >> [quoted text clipped - 44 lines] > relation coming from the designer-generated code? Or did he add it > programmatically or to the DataSet in the designer? I should have mentioned that the MembershipDataSet is generated using CodeDom, but not by Visual Studio, so essentially the DataRelation was added programmatically in the constructor. >Is there a datarelation defined in the database like a foreign key? If >there > is a foreign key, then there is a data relation. There are no foreign-key constraints in the source database, yet. The only relationship is the programmatic DataRelation in the MembershipDataSet. As I said, I should've mentioned that all the data-related types in my solution have been generated using code that I wrote. And there lies my concern, I've probably missed something. BTW I'm not a glutton for punishment. The reason for creating data access code this way is that ODP.NET and Oracle DB Lite don't work, or at least don't work very well with the DataSet Designer in VS. Thanks for all replies Glenn Hi, > Responses inline... > [quoted text clipped - 63 lines] > solution have been generated using code that I wrote. And there lies my > concern, I've probably missed something. Yes, you should have mentioned that :-) since the problem doesn't occure with the VS generated typed dataset , big chances are you've made some mistake building your own typed DataSet. It's also possible that something is wrong with your typed dataset that is making the WinForm designer add the DataRelation another time. A quick look at the VS generated typed DataSet did reveal some interesting code that prevents the WinForm designer from serializing the DataRelations (adding code inside InitializeComponent). The WinForm designer shouldn't serialize the DataRelations since they are default ones build inside the constructor. public new System.Data.DataRelationCollection Relations { get { return base.Relations; } } protected override bool ShouldSerializeRelations() { return false; } But the same thing is done for DataTables though you don't mention anything about duplicated tables... HTH, Greetings > BTW I'm not a glutton for punishment. The reason for creating data access > code this way is that ODP.NET and Oracle DB Lite don't work, or at least [quoted text clipped - 3 lines] > > Glenn Bart I hadn't overridden ShouldSerializeRelations. As simple as that. Many thanks Glenn > Hi, > [quoted text clipped - 102 lines] >> >> Glenn Hi, >> Hi, >> >>> Hi [snipped] >>> I realise I could do the necessary to get everything working just as I'd >>> like it to by hand, but I'm curious as to why it tries to create the [quoted text clipped - 10 lines] > Customers and Orders tables from Northwind in it; you will see > the relation between them drawn automatically. Yes, the DataSet designer can add relations but that's not a or the problem. But with designer i only meant the WinForm designer, the WinForm designer shouldn't add a relations to a typed dataset. Greetings > My question for OP is this: is the MembershipDataSet's "baked-in" > relation coming from the designer-generated code? Or did he add it [quoted text clipped - 3 lines] > > Robin S. > Hi, > [quoted text clipped - 24 lines] > > Greetings Gotcha. Thanks for clarifying. Robin S. Free MagazinesGet these publications absolutely FREE for up to 12 months. 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