Annotating a property of type Guid as DocumentProperty.Key throws InvalidCastException

[TommyEmmanuel]

As the title suggests, I have had all my class Id properties decorated with [DocumentProperty(Identifier = IdentifierType.Key)] All Id properties are of type System.Guid and thus far had no issues with it. As a matter of fact, i used a generic base type to get any type on Id property on all my entities.

        public abstract class BaseEntity<TId> : IEntity<TId>
        {
            [DocumentProperty(Identifier = IdentifierType.Key)]
            [DataMember(Name = "id")]
            public TId Id { get; set; }
        }

and it worked wonderfully. I have been using this originally in the prior version v0.7.6. Since the update, I've been getting InvalidCastException with the message:

Unable to cast object of type 'System.String' to type 'System.Guid'.

The exception happens somewhere within a lambda expression and the closest to the line of code where i have been able to investigate is: ArangoDB.Client.Property.DocumentIdentifierModifier in the line 55 This line tries to generically create a SetValue (there is even a stackoverflow link attached)

I have also tried cloning the project and updating all the nuget references thinking it would help, but no progress there.

This breaking change happened with the updated version v0.7.70.

[dkincer87]

I am also having the same issue with inserting a vertex.

[DocumentProperty(Identifier = IdentifierType.Key)]
public Guid Id { get; set; }

When hitting the arango .net method

IDocumentIdentifierResult result = await graph.InsertVertexAsync<Tnode>(node);

It tries to return the interface which is expecting a string instead of a Guid. Is there a way to patch this to allow the interface Key to be the type we assign the DocumentProperty?

[Alan5142]

This can be solved using TypeDescriptor.GetConverter as shown here:

var methods = FindIdentifierMethodFor(document.GetType());
methods.SetKey(document, TypeDescriptor.GetConverter(PROPERTY_TYPE).ConvertFrom(identifiers.Key));

PROPERTY_TYPE is the type of the property that will obtain the value

In my local branch I edited the following file to be able to use Guid as an Id type: DocumentIdentifierModifier.cs

public class IdentifierMethod
{
    public IdentifierMethod()
    {
        this.SetKey = this.SetRevision = this.SetHandle = (x, y) => { };
    }
    // this was added
    public Type KeyType { get; set; }

    public Action<object, object> SetKey { get; set; }
    public Action<object, object> SetHandle { get; set; }
    public Action<object, object> SetRevision { get; set; }
    public Action<object, object> SetFrom { get; set; }
    public Action<object, object> SetTo { get; set; }
}

public IdentifierMethod FindIdentifierMethodFor(Type type)
{
    IdentifierMethod identifierMethod = null;
    if (!methods.TryGetValue(type, out identifierMethod))
    {
        identifierMethod = new IdentifierMethod();
        var typeMemberInfos = ReflectionUtils.GetFieldsAndProperties_PublicInstance(type);
        foreach (var m in typeMemberInfos)
        {
            string resolvedName = setting.Collection.ResolvePropertyName(type, m.Name);

            switch (resolvedName)
            {
                case "_key":
                    // following line was added
                    identifierMethod.KeyType = ReflectionUtils.GetProperty(type, m.Name).PropertyType;
                    identifierMethod.SetKey = BuildSetAccessor(type, m.Name);

public void Modify(object document, IDocumentIdentifierResult identifiers)
{
    if (identifiers.Id != null && identifiers.Key != null && identifiers.Rev != null)
    {
        var methods = FindIdentifierMethodFor(document.GetType());
        // Use type converter
        methods.SetKey(document, TypeDescriptor.GetConverter(methods.KeyType).ConvertFrom(identifiers.Key));
        methods.SetHandle(document, identifiers.Id);
        methods.SetRevision(document, identifiers.Rev);
    }
}

public void Modify(object document, IDocumentIdentifierResult identifiers, string from, string to)
{
    if (identifiers.Id != null && identifiers.Key != null && identifiers.Rev != null)
    {
        var methods = FindIdentifierMethodFor(document.GetType());
        // // Use type converter
        methods.SetKey(document, TypeDescriptor.GetConverter(methods.KeyType).ConvertFrom(identifiers.Key));
        methods.SetHandle(document, identifiers.Id);
        methods.SetRevision(document, identifiers.Rev);
        methods.SetFrom(document, from);
        methods.SetTo(document, to);
    }
}

If you want to use another type, be sure that the destination type has a type converter from string 😄 I will make a PR after the PR that I made a few hours ago is accepted