VpcNetwork return error of its subnet properties

[McDoit]

Describe the bug
Subnets configurations from a newly created VPC throws Type reference has a fully qualified name, but is neither a class nor an enum Parameter name: reference when trying to access the xSubnets properties of the vpc object

To Reproduce
Creating a new VPC with

var subnets = new ISubnetConfiguration[]
{
    new SubnetConfiguration { CidrMask = 28, Name = "Public", SubnetType = SubnetType.Public },
    new SubnetConfiguration { CidrMask = 28, Name = "Private", SubnetType = SubnetType.Private },
    new SubnetConfiguration { CidrMask = 28, Name = "Db", SubnetType = SubnetType.Private },
};

var vpc = new VpcNetwork(this, "vpc", new VpcNetworkProps
{
    Cidr = "172.30.0.0/22",
    EnableDnsHostnames = true,
    EnableDnsSupport = true,
    NatGatewaySubnets = new SubnetSelection
    {
        SubnetType = SubnetType.Public
    },
    SubnetConfiguration = subnets,
    NatGateways = 1,
    MaxAZs = 2
});

Then try to access the vpc.PrivateSubnets property

Expected behavior
To get the array of the different subnet types

Version:

• Windows 10
• C#/dotnet core 2.1
• CDK 0.28

[McDoit]

Found a workaround, given that you want the subnets named Private you can use this method:

            private IEnumerable<T> GetSubnetsByName<T>(IIVpcNetwork vpc, string subnetName) where T : class
            {
                return Enumerable.Range(1, vpc.AvailabilityZones.Length).Select(s => $"{subnetName}Subnet{s}")
                    .Select(s => vpc.Node.FindChild(s) as T);
            }

and then use this snippet in your code:

 var privateSubnetIds = GetSubnetsByName<VpcPrivateSubnet>(vpc, "Private").Select(s => s.SubnetId).ToArray();