Dynamically build select list from linq to entities query

Question

I\'m looking for a way to dynamically create a select list from a iQueryable object.

Concrete example, i want to do something like the following:

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Answer 1

I believe this is what you need:

var entities = new List();

entities.Add(new User { Name = "First", Type = "TypeA" });
entities.Add(new User { Name = "Second", Type = "TypeB" });

string[] columns = { "Name", "Type" };

var selectResult = new List();

foreach (var columnID in columns)
{
    selectResult.AddRange(entities.Select(e => e.GetType().GetProperty(columnID).GetValue(e, null).ToString()));
}

foreach (var result in selectResult)
{
    Console.WriteLine(result);
}

This code outputs:

• First
• Second
• TypeA
• TypeB

UPDATE (according to comments)

// initialize alist of entities (User)
var entities = new List();
entities.Add(new User { Name = "First", Type = "TypeA", SomeOtherField="abc" });
entities.Add(new User { Name = "Second", Type = "TypeB", SomeOtherField = "xyz" });

// set the wanted fields
string[] columns = { "Name", "Type" };

// create a set of properties of the User class by the set of wanted fields
var properties = typeof(User).GetProperties()
                        .Where(p => columns.Contains(p.Name))
                        .ToList();

// Get it with a single select (by use of the Dynamic object)
var selectResult = entities.Select(e =>
{
    dynamic x = new ExpandoObject();
    var temp = x as IDictionary;
    foreach (var property in properties)
        temp.Add(property.Name, property.GetValue(e));
    return x;
});

// itterate the results
foreach (var result in selectResult)
{
    Console.WriteLine(result.Name);
    Console.WriteLine(result.Type);
}

This code outputs:

• First
• TypeA
• Second
• TypeB