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I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this

public enum Gender
{
    Male,
    Female
}

Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported.

Any ideas on how to do this mapping. Am I missing something on the enums.

uriDium
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2 Answers2

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If you have an int enum like this:

public enum Gender
{
    Male = 0,
    Female
}

and int column in your database, the next mapping should work without problem.

<Column Name="Gender" Type="global::Project.Models.Gender" DbType="Int NOT NULL"
        CanBeNull="false" />

It is possible that global:: keyword is a key here. I had some problems with mapping integer data types to enums without it.

Oleks
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  • I have also added the global:: from another post and the build problems have gone away and now it is saving into the database correctly. My next problem is when I do a linq select. It is giving me invalid cast exceptions. I am not sure if it is related to the enum I have used. Does the DbType have to be non null? – uriDium Apr 21 '10 at 20:14
  • @uriDium: I didn't use nullable enumerations with LINQ, but suppose it should work: set DbType="Int" and CanBeNull="true". – Oleks Apr 21 '10 at 20:20
  • Okay, I tried everything again. Maybe something got confused. I redragged the table into the designer, changed the type again and presto everything works. I thought the global:: bus was meant to have been sorted out. Guess not. Thanks – uriDium Apr 21 '10 at 20:23
  • Alex, do you have to modify the DBML by hand to do this? What happens when someone refreshes the object in the DBML designer? Does your change get wiped out? – Robert Harvey Apr 21 '10 at 20:32
  • @Robert Harvey: yes, most of the changes to model I've made by hand on my last project. The thing is: the project is expanding, alongside with project the data layer is expanding too. I have to add new fields to the database quite often. For me it is not too comfortable doing this using designer. One more thing: the designer is quite buggy (I tried to add 2 tables some time ago but the try was unsuccessful). But happily, I'm the only one person who working with the data/BLL. – Oleks Apr 21 '10 at 20:51
  • The designer is stable if you refresh the Server Explorer, and save before *and* after adding the tables, IME. – Robert Harvey Apr 22 '10 at 14:40
2

I've found that whereas 

Type="System.Boolean" DbType="bit" CanBeNull="true"

works out that the type should be a nullable[of boolean], for an enum I have to specify the type as the nullable type..

Type="WhatNextEnum?" DbType="int" CanBeNull="true"

If you don't you'll get the "DBML1005: Mapping between DbType 'int' and Type 'WhatNextEnum' ... is not supported." error

Paul Nicklin
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