The QueryBuilder that was created with this book gives great flexibility

Carterly · December 26th, 2012, 04:22 AM

I tried enumerating through the QueryFields in the Builder right after calling the GetCustomAttributes method. But I failed because it's of type object[] and I tried doing something like:
IEnumerable<QueryFieldAttribute> qfa = QueryFields.OrderBy(q => q.FriendlyFieldName);

I'm completely shooting in the dark on this since I never worked with QueryFieldAttributes till now. Is there a simple way of doing this and I'm just completely looking at this wrong..?

philip_cole · December 31st, 2012, 10:36 AM

Hi Carterly,

Type.GetCustomAttributes will always return an object array, so in your LINQ statement, q is of type object. You will need to cast each one to QueryFieldAttribute to check it.

Luckily there is a Cast() method in LINQ to do it for you! So you can use:

Code:

IEnumerable<QueryFieldAttribute> queryFieldAttrs = QueryFields.Cast<QueryFieldAttribute>();

IEnumerable<QueryFieldAttribute> qfa = queryFieldAttrs.OrderBy(q => q.FriendlyFieldName);

Be careful tho, as this will error if the attribute isn't a QueryFieldAttribute or inherited from it. You can see in the QueryBuilder code that it checks if the attribute is a QueryFieldAttribute before using it.

You could of course get round this by extending ENTBaseQueryBO to create a second version of GetCustomAttributes() which takes an attribute type:

Code:

public object[] GetCustomAttributes(Type attributeType)
{
    return typeof(T).GetCustomAttributes(attributeType, false);
}

Hope this gives you some ideas

Phil