Linq-to-SQL ToDictionary()

Question

How do I properly convert two columns from SQL (2008) using Linq into a Dictionary (for caching)?

I currently loop through the IQueryable b/c I can't get the ToDictionary method to work. Any ideas? This works:

var query = from p in db.Table
            select p;

Dictionary<string, string> dic = new Dictionary<string, string>();

foreach (var p in query)
{
    dic.Add(sub.Key, sub.Value);
}

What I'd really like to do is something like this, which doesn't seem to work:

var dic = (from p in db.Table
             select new {p.Key, p.Value })
            .ToDictionary<string, string>(p => p.Key);

But I get this error: Cannot convert from 'System.Linq.IQueryable' to 'System.Collections.Generic.IEnumerable'

Answer 1

var dictionary = db
    .Table
    .Select(p => new { p.Key, p.Value })
    .AsEnumerable()
    .ToDictionary(kvp => kvp.Key, kvp => kvp.Value)
;

Answer 2

You are only defining the key, but you need to include the value also:

var dic = (from p in db.Table
             select new {p.Key, p.Value })
            .ToDictionary(p => p.Key, p=> p.Value);

Answer 3

Thanks guys, your answers helped me fix this, should be:

var dic = db
        .Table
        .Select(p => new { p.Key, p.Value })
        .AsEnumerable()
        .ToDictionary(k=> k.Key, v => v.Value);

Answer 4

Why would you create an anonymous object for every item in the table just to convert it?

You could simply use something like: IDictionary<string, string> dic = db.Table.ToDictionary(row => row.Key, row => row.Value); You may need to include an AsEnumerable() call between Table and ToDictionary(). I don't know the exact type of db.Table.

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Also correct the first sample, your second loop variable is mismatching at declaration and usage.