How can I use an extended entity to create a new property in my EF6 class with property changed notification? - entity-framework

Question

I have a table in my entity model called prices. It has several fields named value0, value1, value2, value3, value4... (these are their literal names, sigh..). I cannot rename them or in any way change them.
What I would like is to use an extended entity to create a new property called values. This would be a collection containing value1, value2 etc...
To get access to the values I would then simply need to write prices.values[1]
I need property changed notification for this.
So far I have tried this;
public partial class Prices
{
private ObservableCollection<double?> values = null;
public ObservableCollection<double?> Values
{
get
{
if (values != null)
values.CollectionChanged -= values_CollectionChanged;
else
values = new ObservableCollection<double?>(new double?[14]);
values[0] = value0;
values[1] = value1;
values[2] = value2;
values.CollectionChanged += values_CollectionChanged;
return values;
}
private set
{
value0 = value[0];
value1 = value[1];
value2 = value[2];
}
}
private void values_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
{
Values = values;
}
}
The issue comes when trying to set values. if I try to set a value by writing
prices.values[0] = someValue;
The new value is not always reflected in the collection (i.e. when I have previously set value and then try to overwrite the value).
I am willing to try any approach that would achieve my goal, I am not precious about having my solution fixed (although if anyone can explain what I'm missing that would be great!)

Answer 1

You could implement an indexer on Prices class without using a collection.
You can use switch to select the property to write or you can use reflection.
In this case I use reflection.
public double? this[int index]
{
get
{
if (index < 0 || index > 13) throw new ArgumentOutOfRangeException("index");
string propertyName = "Value" + index;
return (double?)GetType().GetProperty(propertyName).GetValue(this);
}
set
{
if (index < 0 || index > 13) throw new ArgumentOutOfRangeException("index");
string propertyName = "Value" + index;
GetType().GetProperty(propertyName).SetValue(this, value);
// Raise your event here
}
}