/// <summary>
/// Performs expression replacement and then delegates to the wrapped provider to create an
/// <see cref="ObjectQuery" />.
/// </summary>
protected ObjectQuery CreateObjectQuery(Expression expression)
{
DebugCheck.NotNull(expression);
expression = new DbQueryVisitor().Visit(expression);
return((ObjectQuery)((IQueryProvider)_provider).CreateQuery(expression));
}
private static Expression CreateObjectQueryConstant(object dbQuery)
{
ObjectQuery objectQuery = DbQueryVisitor.ExtractObjectQuery(dbQuery);
if (objectQuery == null)
return (Expression) null;
Type key = ((IEnumerable<Type>) objectQuery.GetType().GetGenericArguments()).Single<Type>();
Func<ObjectQuery, object> func;
if (!DbQueryVisitor._wrapperFactories.TryGetValue(key, out func))
{
func = (Func<ObjectQuery, object>) Delegate.CreateDelegate(typeof (Func<ObjectQuery, object>), typeof (ReplacementDbQueryWrapper<>).MakeGenericType(key).GetDeclaredMethod("Create", typeof (ObjectQuery)));
DbQueryVisitor._wrapperFactories.TryAdd(key, func);
}
object obj = func(objectQuery);
return (Expression) Expression.Property((Expression) Expression.Constant(obj, obj.GetType()), "Query");
}
private static DbContext GetContextFromConstantExpression(
Expression expression,
MemberInfo member)
{
if (expression == null)
return DbQueryVisitor.GetContextFromMember(member, (object) null);
ConstantExpression constantExpression = expression as ConstantExpression;
if (constantExpression != null)
{
object obj = constantExpression.Value;
if (obj != null)
return DbQueryVisitor.GetContextFromMember(member, obj);
}
return (DbContext) null;
}
protected override Expression VisitMember(MemberExpression node)
{
Check.NotNull<MemberExpression>(node, nameof (node));
PropertyInfo member = node.Member as PropertyInfo;
MemberExpression expression = node.Expression as MemberExpression;
if (member != (PropertyInfo) null && expression != null && (typeof (IQueryable).IsAssignableFrom(member.PropertyType) && typeof (DbContext).IsAssignableFrom(node.Member.DeclaringType)))
{
DbContext constantExpression = DbQueryVisitor.GetContextFromConstantExpression(expression.Expression, expression.Member);
if (constantExpression != null)
{
Expression objectQueryConstant = DbQueryVisitor.CreateObjectQueryConstant(member.GetValue((object) constantExpression, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, (Binder) null, (object[]) null, (CultureInfo) null));
if (objectQueryConstant != null)
return objectQueryConstant;
}
}
return base.VisitMember(node);
}
protected override Expression VisitMethodCall(MethodCallExpression node)
{
Check.NotNull<MethodCallExpression>(node, nameof (node));
if (typeof (DbContext).IsAssignableFrom(node.Method.DeclaringType))
{
MemberExpression memberExpression = node.Object as MemberExpression;
if (memberExpression != null)
{
DbContext constantExpression = DbQueryVisitor.GetContextFromConstantExpression(memberExpression.Expression, memberExpression.Member);
if (constantExpression != null && !node.Method.GetCustomAttributes<DbFunctionAttribute>(false).Any<DbFunctionAttribute>() && node.Method.GetParameters().Length == 0)
{
Expression objectQueryConstant = DbQueryVisitor.CreateObjectQueryConstant(node.Method.Invoke((object) constantExpression, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic, (Binder) null, (object[]) null, (CultureInfo) null));
if (objectQueryConstant != null)
return objectQueryConstant;
}
}
}
return base.VisitMethodCall(node);
}
protected ObjectQuery CreateObjectQuery(Expression expression)
{
expression = new DbQueryVisitor().Visit(expression);
return((ObjectQuery)((IQueryProvider)this._internalQuery.ObjectQueryProvider).CreateQuery(expression));
}
