Entity Framework Code First: How can I determine the foreign key property used for a navigation property at runtime? -

i have entity framework code first dbcontext following entities configured. in example class bar child of class foo.

public class foo {     public guid id { get; set; }      public virtual icollection<bar> bars { get; set; } }  public class bar {     public guid id { get; set; }      public guid fooid { get; set; }      public virtual foo foo { get; set; } } 

now know internally, entity framework understands relationship between foo , bar defined foreign key bar.fooid. i'd somehow extract relationship @ runtime using expressions. i'd implement method behaves follows:

var context = new foobardbcontext(); var bar = context.set<bar>().first();  // want method return bar.fooid when passed expression b => b.foo object result = myservice.getforeignkeyvalue(bar, b => b.foo);  

now in simplistic example know bar.fooid , done. point i'm writing class believe getforeignkeyvalue method specified above cleanest interface user.

is possible query dbcontext configuration determine property used foreign key navigation property? (assuming there one)

i able determine foreign key properties using getdependentproperties method of navigationproperty class.

here code used (more or less) needed:

object[] getforeignkeypropertyvalues<tentity, trelatedentity>(tentity entity, expression<func<tentity, trelatedentity>> navigationproperty) {     if (entity == null)         return new object[] { };      // find entity metadata in object context.     // (assume have access dbcontext through property currentdbcontext.)     var objectcontext = (currentdbcontext iobjectcontextadapter).objectcontext;       var metadatanamespace = objectcontextadapter.gettype().namespace;      var entityidentity = metadatanamespace + "." + typeof(tentity).name; // hack: seems work retrieve entitytype entity.     var entitymetadata = objectcontext.metadataworkspace.getitem<entitytype>(entityidentity, dataspace.cspace);      // todo: verify entity metadata found.      // navigation property metadata parsing name navigation property expression.     var navigationpropertyname = getpropertyname(navigationproperty);     var navigationpropertymetadata = entitymetadata.navigationproperties.firstordefault(np => np.name == navigationpropertyname);      // todo: (jmb) verify navigation property metadata found.      // extract foreign key columns navigation property.     var foreignkeypropertymetadatas = navigationpropertymetadata.getdependentproperties();      // create property getters each foreign key property.     var foreignkeypropertygetters = foreignkeypropertymetadatas         .select(propertymetadata => makepropertygetter<tentity>(propertymetadata.name))         .toarray();      // execute foreign key property getters foreign key property values specified entity.     var foreignkeypropertyvalues = foreignkeypropertygetters         .select(propertygetter => propertygetter(entity))         .toarray();      return foreignkeypropertyvalues; }  static string getpropertyname<tentity, tproperty>(expression<func<tentity, tproperty>> navigationproperty) {     var lambda = navigationproperty lambdaexpression;     var member = lambda.body memberexpression;      return member.member.name; }  static func<tentity, object> makepropertygetter<tentity>(type entitytype, string propertyname) {     var parameterexpression = expression.parameter(typeof(tentity), "entity");     var propertyexpression = expression.propertyorfield(parameterexpression, propertyname);      var lambdaexpression = expression.lambda(propertyexpression, parameterexpression);     var lambdafunction = lambdaexpression.compile();      return (func<tentity, object>)lambdafunction; }