Operation is not valid due to the current state of the object. on .GetBackingfield() about mono.reflection

[jbevain]

It's possible that you're hitting an indexer. Currently GetBackingField works only for traditional properties. Could you paste the code of the property that triggers the exception ?

[joergbattermann]

Oh now that was quick :)

The property & backingfield are the following:

private string _department;

    /// <summary>
    /// Gets or sets the department.
    /// </summary>
    /// <value>The department.</value>
    public string Department
    {
        get
        {
            Activate(ActivationPurpose.Read);
            return _department;
        }
        set
        {
            Activate(ActivationPurpose.Write);
            _department = value;
        }
    }

(it's using db4o's transparent activation mechanism in the Property there)

[jbevain]

GetBackingField reads the IL of the property to find a certain pattern, specific to simple properties. As you have calls to methods in them, they stop being simple properties.

Now, it's possible to write a custom IL pattern to look for. That's your lucky day, I already wrote the pattern for db4o properties here:

http://source.db4o.com/db4o/trunk/db4o.net/Db4objects.Db4o.Linq/Db4objects.Db4o.Linq/CodeAnalysis/ReflectionMethodAnalyser.cs

[joergbattermann]

Nice! Thanks Jean-Baptiste for the quick help!