C# - Adding A Custom Property To Entity Framework?
Oct 19, 2010
I am using the Entity Framework for the first time and want to know if the following is possible - I have generated my classes from the DB, and have one called Category.
Obviously it has all my fields in the table (ID, CategoryName, SortOrder etc..) but I want to know if I can add a custom property which is not in the table, but is actually the result of a custom method.
I want to add a new property called 'CategoryURL' which is basically the 'CategoryName' property run through a custom method and returns a hyphenated string.
My initial thought is inheriting from the generated Category class and creating something like this inside?
public string CategoryURL
{
get{ return MyCustomMethod(this.CategoryName) }
}
Is this the correct approach? And will 'this.CategoryName' work as I think it should? Basically the end result is when I return a list of 'Category' I want this to be part of the class so I can use it in my foreach loop.
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Aug 5, 2010
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Feb 2, 2011
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Apr 22, 2010
I have a question, much liket this unanswered one. I'm trying to work with the entity framework, and having a tough time getting my foreign tables to update. I have something basically like this in the DB:
Incident (table):
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Responses (table):
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And and entities that match:
Incident (entity)
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In my Webpage, I have a form to allow the user to enter all the details of an Incident, including a list of responses. I can add everything to the database when a new Incident is created, however I'm having difficulty with editing the Incident.
When the page loads for edit, I populate the form and then store the responses in the viewstate. When the user changes the list of responses (adds one, deletes one or edits one). I store this back into the viewstate. Then when the user clicks the save button, I'd like to save the changes to the Incident and the Responses back to the DB. I cannot figure out how to get the responses from the detached viewstate into the Incident object so that they can be updated together.
Currently when the user clicks save, I'm getting the Incident to edit from the db, making changes to the Incident's fields and then saving it back to the DB. However I can't figure out how to have the detached list of responses from the viewstate attach to the Incident. I have tried the following without success:
Clearning the Incident.Responses collection and adding the ones from the viewstate back in:
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for each objResponse in Viewstate("Responses")
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next
Creating an EntityCollection from my list and then assiging that to the Incident.Responses
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Iterating through the responses in Incident.Response and assigning the corresponding object from viewstate:
for each ObjResponse in Incident.Responses
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Mar 1, 2011
I've been at this same question in different forms now for a while (see e.g. Entity Framework and MVC 3: The relationship could not be changed because one or more of the foreign-key properties is non-nullable. ), and it's still bugging me, so I thought I'd put it a little more generically:
You have an entity object (using Entity Framework), say User. The User has some simple properties such as FirstName, LastName, etc. But it also has some object property lists, take the proverbial example Emails, to make this simple. Email is often designed as a list of objects so that you can add to that object properties like Address and Type (Home, Work, etc). I'm using this as an example to keep it generic, but it could be anything, the point is, you want the user to be able to add an arbitrary number of these items. You should also be able to delete items (old address, or whatever).
Now, in a normal web page you would expect to be able to add these items in the same View. But MVC as it seems designed only makes it easy to do this if you call up an entirely new View just to add the address. (In the template for an Index View you get the "Create New" link e.g.).
I've come across a couple of examples that do something close to what I mean here:
[URL]
and
[URL]
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[Code]....
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[Code]....
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[Code]....
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[Code]....
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