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A general validation attribute for checking uniqueness in a linq to sql data context

Posted By:      Posted Date: September 04, 2010    Points: 0   Category :ASP.Net
I've been programming asp.net for, oh, a couple of days now. Here's a question I can't even begin to figure out for myself. I hope it's obvious from the code what I want to accomplish, and I have, but it's not pretty. Furthermore I'd like to use it on whatever table, whatever field, i.e. check the uniqueness of a value against a table and field I specify, passing it all into the attribute constructor. public class UniqueEmailAttribute : ValidationAttribute{    public UniqueEmailAttribute()    {    }    public override Boolean IsValid(Object value)    {        //not pretty. todo: do away with this.        var db = new CoinDataContext();        int c = db.Emails.Count(e => e.Email1 == value.ToString());        return (Boolean) (c == 0);    }}

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I'm not sure how to structure the code for this but what I want to do is be able to add data to a database, and once this has completed successfully, then email the user to say the details have been added successfully to the database.

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The type 'System.Data.Linq.DataContext' is defined in an assembly that is not referenced. You must



This is frustrating, and I don't know how to solve it.

I have a strange problem. I am adding a LinqDatasource object, and set the context:

        protected void LinqDataSource_ContextCreating(object sender, LinqDataSourceContextEventArgs e)
            e.ObjectInstance = new KaruselaDataContext(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString);

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On web.config I already have this:
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NOTE: The datacontext is in a different project (DLL proect) where I added a refernce to System.Data.Linq.

is there another way adding a refernce to a web project? or only though teh web.config?


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