Linq to Sql - How to handle Foreign Keys RSS

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  NewToDotNet

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  734 Posts

  Linq to Sql - How to handle Foreign Keys

  Aug 09, 2010 01:17 PM|LINK

  I am building an ASP.NET 3.5 web application using C# and Linq to SQL.  This is my first attempt at using Linq to SQL so I have a few questions. 

  This application is pretty much data driven as opposed to domain driven (not my choice).  In this application have have the following tables:

  • VendorMaster
  • VendorAddresses
  • Addresses

  The VendorAddresses table has two Foreign Keys

  1. VendorMaster
  2. Addresses

  I was working on creating a new VendorAddress record and I ran into all sorts of problems on my InsertOnSubmit/SubmitChanges.  At first I thought that I could just set the VendorMaster ID and the Addresses ID properties on the VendorAddresses record, but that didn't work as Linq to Sql threw an error.  It seems that the only way that I could get around the problems that I was having was to either read or attach the VendorMaster and Addresses record to the VendorAddresses record.

  My questions are as follows:

  1. Can anyone explain why this has to be done as opposed to setting the foreign key id's like VendorMaster ID and Address ID on the VendorAddresses entity?
  2. If I decided I wanted to create a new VendorMaster and a new VendorAddress address record would the InsertOnSubmit to the VendorMaster record be enough if the VendorMaster entity had an attached VendorAddress or would I still need to do a seperate InsertOnSubmit for the VendorAddress?  In other words is Linq to Sql smart enough to look at the entity and apply the proper changes?
  3. If there a good book or blog that describes how to handle foreign key relationships using Linq to SQL?

  Thanks

  ps. If it makes any difference, I move the data from the entity classes into DTO classes when I read the data and move the data from DTO classes to the entity classes when I write the data.

   

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  Ahmed.Mostaf...

  Member

  309 Points

  54 Posts

  Re: Linq to Sql - How to handle Foreign Keys

  Aug 09, 2010 01:32 PM|LINK

  check the post below 

  http://forums.asp.net/t/1577799.aspx

  
  

  categoryAttribute ct = new categoryAttribute();
  
  
  ct.category = new category();
  
  
  ct.category.blablabla  = "blablabla";
  
  
  ct.blablabla= "blablabla';
  
  
  DatacontextObj.categoryAttributes.InsertOnsubmit(ct);
  
  
  DatacontextObj.SubmitChanges();

  
  
  

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  NewToDotNet

  Participant

  1052 Points

  734 Posts

  Re: Linq to Sql - How to handle Foreign Keys

  Aug 09, 2010 01:51 PM|LINK

  Ahmed.Mostafa

  check the post below 

  http://forums.asp.net/t/1577799.aspx

  
  

   

  <div class=dp-highlighter> <div class=bar> <div class=tools>view plaincopy to clipboardprint?</div></div>

  1. categoryAttribute ct = new categoryAttribute();   
  2.   
  3. ct.category = new category();   
  4.   
  5. ct.category.blablabla  = "blablabla";   
  6.   
  7. ct.blablabla= "blablabla';   
  8.   
  9. DatacontextObj.categoryAttributes.InsertOnsubmit(ct);   
  10.   
  11. DatacontextObj.SubmitChanges();  

  </div>

  categoryAttribute ct = new categoryAttribute();
  
  
  ct.category = new category();
  
  
  ct.category.blablabla  = "blablabla";
  
  
  ct.blablabla= "blablabla';
  
  
  DatacontextObj.categoryAttributes.InsertOnsubmit(ct);
  
  
  DatacontextObj.SubmitChanges();

   

  I would like to thank you for the quick response.  While I do understand what you posted, it would help me understand why as to opposed to how to handle foreign keys if you could answer the questions I posed.  For instance, why can't I just set the ID fields on my VendorAddresses table, or if doing one insertonsubmit to my VendorMaster entity also save changes to the attached VendorAddress?

  Thanks