how can I code a recursive query in an Entity Framework model?

I have a model which includes NODES, and RELATIONSHIPS (that tie the nodes together, via a parent_node, child_node arrangement).

Q1 - Is there any way in EF / Linq-to-entities to perform a query on nodes (e.g. context.Nodes..) to find say "all parents" or "or children" in the graph?

Q2 - If there's not in Linq-to-entities, is there any other way to do this other than writing a method that manually goes through and doing it?

Q3 - If manual is the only way to do it, should I be concerned about the number of database hits that will be going out to the database as the method keeps recursing through the data? Or mor开发者_JS百科e specifically, is there any EF caching type feature that might assist here in ensuring the method is performance from a "number of database hits" point of view?

thanks

thanks

There is no such elegant way to flaten a tree. you can (in stored proc or in entity framework) create a loop that will run untill no change happend, in which iteration you will bind parent and child's child in some temp table or collection. in the end you will have a collection of parents, sucsessor two-ples.

When you are using Microsoft SQL Server 2005 or up, you can use CTEs (Common Table Expressions). They allow you do define a recursive query. While SQL Server under the covers doesn't do much more than firing a bunch of queries for you, it does this completely server side, so it saves you from having a lot of client-server communication.

You will have to do this using a stored proc or a normal SQL query, because there is no way EF can do this for you.