Nested classes using entity framework and linq

Question

I have these classes:

public class RegionResult
{
    public string Region { get; set; }
    public List<Unicorn> Unicorns { get; set; }
}

public class Unicorn
{
    public string Name { get; set; }
    public string Color { get; set; }
    public Dictionary<string, string> Parameters { get; set; }
}

And I would assign data to a List from my datacontext. "Flat" query would look like:

SELECT * FROM Regions R 
JOIN Unicorns U ON R.X = U.X
LEFT JOIN Parameters P ON U.X = P.X

I would like to have it grouped by region, and for each region populate with unicorns, and parameters if not null. How would that query look like?

List<RegionResult> regions = (from a in (_entites.Regions).AsEnumerable().GroupBy(...)
.select new... a = a.Unicorn.Name..  new .ToDictionary(key, value)?

Thanks in advance

/Lasse

Jan · Accepted Answer · 2011-08-25 17:37:19Z

2

If i understand you right, you just want to load the Regions with associated Unicorns and Parameters.

You dont have to group, just load the regions and include the related entities (This is for EF 4.1):

List<RegionResult> regions = 
     _entites.Regions.Include(r => r.Unicorns.Select(u => u.Parameters);

But i don't think, that you can map a Dictionary Type with Entity Framework.

answered Aug 25, 2011 at 17:37

Jan

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3 Comments

Lasse Edsvik Over a year ago

I got entity framework 4.1 installed and I cant use lamda expressions for some reason.. only string parameter avalible

Lasse Edsvik Over a year ago

Seems you have some class that extends objectquery

Jan Over a year ago

@Lasse Edsvik: Its an extension method. You have to include the namespace System.Data.Entity. See this walkthrough on EF 4.1: blogs.msdn.com/b/adonet/archive/2011/01/31/…

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