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POEntity Framework Traverse and return child records in self reference table
 

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    <p>I am using Entity Framework and have a table of BusinessUnits which can reference another record of the same type to form a child-parent hierarchy.</p> <p>I also have a set of users, and user permissions, where each user defined in this table should have access to the BusinessUnit and all sub-business units in the hierarchy. Users should not have access to the BusinessUnit above the one referenced (if exists).</p> <p>How can I go about forming LINQ queries to handle this self-referencing relationship tree and return all the business units (with child units) for which this user has access? Is it possible to do it in one query, or do I need to manually build the tree myself with a for-loop?</p> <p>I have seen schema's reference in this way from node to parent, does this mean I have to start at the furthest child node to build the tree by one parent at a time?</p> <p>Thanks in advance,</p> <p>Chris</p> <pre><code>class BusinessUnit { int BusinessUnitID {get;set;} public string BusinessName {get;set;} BusinessUnit ParentBusinessUnit {get;set;} } class User { int UserID {get;set;} string Firstname {get;set;} } class UserPermissions { [Key, ForeignKey("BusinessUnit"), Column(Order = 0)] BusinessUnit BusinessUnit {get;set;} [Key, ForeignKey("User"), Column(Order = 1)] User User {get;set;} } IEnumerable&lt;BusinessUnit&gt; GetUnitsForWhichUserHasAccess(User user) { /* Example 1 given: BusinessUnitA (ID 1) -&gt; BusinessUnitB (ID 2) -&gt; BusinessUnitC (ID 3) with user with ID 1: and UserPermissions with an entry: BusinessUnit(2), User(1) the list { BusinessUnitB, BusinessUnitC } should be returned */ /* Example 2 given: BusinessUnitA (ID 1) -&gt; BusinessUnitB (ID 2) -&gt; BusinessUnitC (ID 3) with user with ID 1: and UserPermissions with an entry: BusinessUnit(1), User(1) the list { BusinessUnitA, BusinessUnitB, BusinessUnitC } should be returned */ } </code></pre>
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