ORMLITE - What is the best way to get an IQueryable object ?

[jpolvora]

I'm using the repository pattern with OrmLite. I have a "Get" method
on which I pass a function to filter the query.
Previously, I was using Entity Framework working with IDbSet/
IObjectSet. The query is performed only when iterating the IEnumerable
object, based on a IQueryable filter.

I was looking the extensions methods of OrmLite, and I found the Each
method, returning IEnumerable, then I can cast it to IQueryable
easily.

Is there another way to achieve this without selecting all data from
DB ?

[Demis Bellot]

Hi Jone,

Firstly there's no IQueryable or Linq in OrmLite it's pretty much just using SQL or filters.

Methods with "Each" in them return back a lazily evaluated list.

Generally you just query by passing in a "where sql", "anon types" or full sql, eg:

var results = dbCmd.Select<Poco>("Name = {0}", name);

var results = dbCmd.Where<Poco>("Name", name);

var results = dbCmd.Where<Poco>(new { Name = name });

var results = dbCmd.Select<Poco>("Select * from Poco Where Name = {0}", name);

var results = dbCmd.Query<Poco>("Select * from Poco Where Name = @name", new { name });

For building of queries the latest version uses a SqlBuilder class which @samsaffron talks about here:

http://samsaffron.com/archive/2011/09/05/Digging+ourselves+out+of+the+mess+Linq-2-SQL+created

You can return a builder class that other code uses to construct the query and then use the builder output in a new dbCmd query, e.g:

var count = dbCmd.QuerySingle<Poco>(count.RawSql, count.Parameters);
var rows = dbCmd.Query<Poco>(selector.RawSql, selector.Parameters);

Micro ORM's are not for everyone and if you have existing code using IQueryable, it might be better to just leave it as-is.

Cheers,

--
- Demis

http://twitter.com/demisbellot

http://www.servicestack.net/mythz_blog