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c#.netreflectiontypedescriptor

How to GetType().GetFields with a custom attribute?


this old code returns a list of fields decorated with an attribute in a method call using reflection

Is there a way to replace it with TypeDescripter or LINQ ?

    public static FieldInfo[] GetFieldsWithAttribute(Type type, Attribute attr, bool onlyFromType)
    {
        System.Reflection.FieldInfo[] infos = type.GetFields();
        int cnt = 0;
        foreach (System.Reflection.FieldInfo info in infos)
        {
            if (info.GetCustomAttributes(attr.GetType(), false).Length > 0)
            {
                if (onlyFromType && info.DeclaringType != type)
                    continue;

                cnt++;
            }
        }

        System.Reflection.FieldInfo[] rc = new System.Reflection.FieldInfo[cnt];
        // now reset !
        cnt = 0;

        foreach (System.Reflection.FieldInfo info in infos)
        {
            if (info.GetCustomAttributes(attr.GetType(), false).Length > 0)
            {
                if (onlyFromType && info.DeclaringType != type)
                    continue;

                rc[cnt++] = info;
            }
        }

        return rc;
    }

Solution

  • public static FieldInfo[] GetFieldsWithAttribute(Type type, Attribute attr, bool onlyFromType)
    {
        System.Reflection.FieldInfo[] infos = type.GetFields();
        var selection = 
           infos.Where(info =>
             (info.GetCustomAttributes(attr.GetType(), false).Length > 0) &&
             ((!onlyFromType) || (info.DeclaringType == type)));
    
        return selection.ToArray();
    }
    

    If you can return an IEnumerable<FieldInfo>, you should be able to return selection directly.