protected override SelectQueryPart VisitSelect(SelectQueryPart select)
{
var parameter = Expression.Parameter(_itemType, "select");
var memberExpressions = select.Selectors
.Select(selector => GetMemberAccessExpression(parameter, selector))
.ToList();
if (memberExpressions.Count > 1)
{
var properties = memberExpressions
.Select(x => x.Member).Cast <PropertyInfo>()
.Select(x => new Property
{
Type = x.PropertyType,
Name = x.Name
});
var selectType = AnonymousTypeManager.BuildType(properties);
var memberBindings = new List <MemberBinding>();
foreach (var memberExpression in memberExpressions)
{
var property = selectType.GetField(memberExpression.Member.Name);
var memberBinding = Expression.Bind(property, memberExpression);
memberBindings.Add(memberBinding);
}
var constructor = Expression.New(selectType);
var initialization = Expression.MemberInit(constructor, memberBindings);
var lambda = Expression.Lambda(initialization, false, parameter);
_expression = Expression.Call(typeof(Queryable), "Select", new[] { _itemType, selectType }, _expression, lambda);
}
else if (memberExpressions.Count > 0)
{
var memberExpression = memberExpressions.Single();
var selectType = memberExpression.Type;
var lambda = Expression.Lambda(memberExpression, false, parameter);
_expression = Expression.Call(typeof(Queryable), "Select", new[] { _itemType, selectType }, _expression, lambda);
}
return(base.VisitSelect(select));
}
public void BuildType_PropertyCollectionContainingSingleProperty_GeneratesTypeCorrectly()
{
var properties = new[]
{
new Property
{
Type = typeof(string),
Name = "TestProperty"
}
};
var type = AnonymousTypeManager.BuildType(properties);
Assert.That(type, Is.Not.Null);
Assert.That(type.Name, Is.EqualTo("TestProperty"));
Assert.That(type.GetFields(BindingFlags.Instance | BindingFlags.Public).Length, Is.EqualTo(1));
}
public void BuildType_EmptyPropertyCollection_ThrowsException()
{
Assert.That(() => AnonymousTypeManager.BuildType(Enumerable.Empty <Property>()), Throws.ArgumentException);
}
public void BuildType_NullPropertyCollection_ThrowsException()
{
Assert.That(() => AnonymousTypeManager.BuildType(null), Throws.InstanceOf <ArgumentNullException>());
}