How to copy an array to extended array?

Question

I have defined my extended class this way:

public class ExtendedAttributeMetadata : AttributeMetadata
{
    public bool IsTwoOption { get; set; }
}

But upon copying the source array of type AttributeMetadata[] to my new destination array ExtendedAttributeMetadata[], i am getting InvalidCastException:

"At least one element in the source array could not be cast down to the destination array type."

Code:

AttributeMetadata[] attributes;
//...
ExtendedAttributeMetadata[] extendedAttributes = new ExtendedAttributeMetadata[attributes.Length];                
attributes.CopyTo(extendedAttributes, 0);

ADDED:

Where AttributeMetadata is derived from MetadataBase

public class AttributeMetadata : MetadataBase

And MetadataBase is an abstract class.

public abstract class MetadataBase : IExtensibleDataObject

Please suggest the best and optimal way of copying in my case.

Where did the original array come from? It seems pretty clear that at least one of the elements of the original array is not of type ExtendedAttribute. — dlev
– dlev, Commented Jun 16, 2013 at 7:08
Original array is of type Attribute[] from which i have extended my class. — Furqan Safdar
– Furqan Safdar, Commented Jun 16, 2013 at 7:15
Your edits don't change anything: you're trying to copy an object that is not of type ExtendedAttributeMetadata into an array of type ExtendedAttributeMetadata. That just isn't possible. — dlev
– dlev, Commented Jun 16, 2013 at 7:39

Reza ArabQaeni · Accepted Answer · 2013-06-16 06:59:03Z

1

You could not copy a base class to derived class so you must be generate it:

var extendedAttributes = 
   attributes.Select(p=>new ExtendedAttribute{IsTwoOption=true/false}).ToArray();

answered Jun 16, 2013 at 6:59

Reza ArabQaeni

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Comments

d h · Accepted Answer · 2013-06-16 07:36:44Z

0

Is the list of attributes just the AttributeMetadata abstract base class?

You are getting that error because there are Attributes in the list that are not of type ExtendedAttributeMetadata

you can filter these out with a linq statement:

var extendedAttributes = attributes.OfType<ExtendedAttributeMetadata>().ToArray();

edited Jun 16, 2013 at 7:36

answered Jun 16, 2013 at 7:20

d h

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1 Comment

d h Over a year ago

the OfType<> filter should still work if you replace ExtendedAttribute with ExtendedAttributeMetadata.

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