public void TreeCreated(DbCommandTreeInterceptionContext interceptionContext)
{
var queryCommand = interceptionContext.Result as DbQueryCommandTree;
if (queryCommand != null)
{
var context = interceptionContext.DbContexts.FirstOrDefault();
if (context != null)
{
DbExpressionVisitor <DbExpression> visitor;
#if (USE_CSPACE)
// Intercepting CSpace instead of SSpace gives us access to all of the navigation properties
// so we are able to handle filters on them as well!
if (interceptionContext.OriginalResult.DataSpace == DataSpace.CSpace)
{
visitor = new DynamicFilterQueryVisitorCSpace(context);
}
else if ((interceptionContext.OriginalResult.DataSpace == DataSpace.SSpace) && DynamicFilterQueryVisitorCSpace.DoesNotSupportElementMethod(context))
{
// Some database (currently Oracle & MySQL) do not support the DbExpression.Element() method that
// is needed when applying filters to child entities. To work around that, we need to also
// visit the query using this SSpace visitor which will apply those filters on all of the DbScan visits.
visitor = new DynamicFilterQueryVisitorSSpace(context);
}
else
{
return;
}
#else
// Old method of visiting only in SSpace. Does not support navigation properties but left
// here in case need to revert or compare results.
if (interceptionContext.OriginalResult.DataSpace == DataSpace.SSpace)
{
visitor = new DynamicFilterQueryVisitorOld(context);
}
else
{
return;
}
#endif
var newQuery = queryCommand.Query.Accept(visitor);
// When using CSpace, must set the useDatabaseNullSemantics parameter to false or nullable types will not have
// null values translated to sql like this: ([Extent1].[TenantID] = @p__linq__0) OR (([Extent1].[TenantID] IS NULL) AND (@p__linq__0 IS NULL))
// and will instead just generate sql like this: [Extent1].[TenantID] = @p__linq__0
// If the parameter is not specified, it defaults to true...
interceptionContext.Result = new DbQueryCommandTree(queryCommand.MetadataWorkspace, queryCommand.DataSpace, newQuery, true,
(interceptionContext.OriginalResult.DataSpace != DataSpace.CSpace));
}
}
// Can also check for other command types such as DbDeleteCommandTree and DbUpdateCommandTree to change
// their behaviors as well. See https://github.com/rowanmiller/Demo-TechEd2014/blob/master/FakeEstate.ListingManager/Models/EFHelpers/SoftDeleteInterceptor.cs
//}
}
private Expression MapAnyOrAllExpression(MethodCallExpression node)
{
if (_DataSpace != DataSpace.CSpace)
{
throw new ApplicationException("Filters on child collections are only supported when using CSpace");
}
if ((node.Arguments == null) || (node.Arguments.Count > 2))
{
throw new ApplicationException("Any function call has more than 2 arguments");
}
// Visit the first argument so that we can get the DbPropertyExpression which is the source of the method call.
var sourceExpression = Visit(node.Arguments[0]);
var collectionExpression = GetDbExpressionForExpression(sourceExpression);
// Visit this DbExpression using the QueryVisitor in case it has it's own filters that need to be applied.
var queryVisitor = new DynamicFilterQueryVisitorCSpace(_DbContext);
collectionExpression = collectionExpression.Accept(queryVisitor);
DbExpression dbExpression;
if (node.Arguments.Count == 2)
{
// The method call has a predicate that needs to be evaluated. This must be done against the source
// argument - not the current binding.
var binding = collectionExpression.Bind();
// Visit the lambda expression against this binding (which will evaluate all of the
// conditions in the expression against this binding and for this filter).
var lambdaExpression = node.Arguments[1] as LambdaExpression;
var visitor = new LambdaToDbExpressionVisitor(_Filter, binding, _DbContext, _DataSpace);
var subExpression = visitor.Visit(lambdaExpression) as LambdaExpression;
var subDbExpression = visitor.GetDbExpressionForExpression(subExpression.Body);
// Create an "Any" or "All" DbExpression from the results
if (node.Method.Name == "All")
{
dbExpression = DbExpressionBuilder.All(binding, subDbExpression);
}
else
{
dbExpression = DbExpressionBuilder.Any(binding, subDbExpression);
}
}
else
{
// This should not even be possible - linq/IEnumerable does not have such a method!
if (node.Method.Name == "All")
{
throw new ApplicationException("All() with no parameters is not supported");
}
// No predicate so just create an Any DbExpression against the collection expression
dbExpression = DbExpressionBuilder.Any(collectionExpression);
}
MapExpressionToDbExpression(node, dbExpression);
return(node);
}
