linq - C# - How do I get an anonymous type and then use the same selector to create an object? -

so i'm trying out azure's new documentdb. unfortunately doesn't allow selectors type. won't let me do:

public ienumerable<u> getall<u>(expression<func<t, u>> selector) {     return client.createdocumentquery<t>(collection.documentslink)         .select(selector)         .asenumerable(); } 

and use as:

// doesn't work return getall(t => new myviewmodel {     id = t.id,     name = t.name,     email = t.email,     url = t.url }); 

it says supports anonymous types. (i imagine since it's new change @ point).

i can solve problem using second select:

return getall(t => new {     id = t.id,     name = t.name,     email = t.email,     url = t.url }).select(t => new myviewmodel() {     id = t.id,     name = t.name,     email = t.email,     url = t.url }).asenumerable(); 

however pain.

is there way use same selector twice , make anonymous first time?

you'll notice signature getall contains expression<func<t, u>> selector. expression part says argument being passed expression tree , not func delegate. it's done way provider can parse selector , generate appropriate database calls (often sql) fetch data.

now, when use specific custom type - in case myviewmodel - provider hits problem - doesn't know how convert type database calls. know how translate anonymous type though.

in returns ienumerable<u> data returned getall in memory can perform subsequent creation of myviewmodel type. there's no need translate database calls more.

so answer design. unlikely new feature in future.