Blob path name provider for WebJob trigger - azure

Question

I have a following test code that is placed inside a WebJob project. It is triggered after any blob is created (or changed) inside "cBinary/test1/" storage account.
The code works.
public class Triggers
{
public void OnBlobCreated(
[BlobTrigger("cBinary/test1/{name}")] Stream blob,
[Blob("cData/test3/{name}.txt")] out string output)
{
output = DateTime.Now.ToString();
}
}
The question is: how to get rid of ugly hard-coded const string "cBinary/test1/" and ""cData/test3/"?
Hard-coding is one problem, but I need to create and maintain couple of such strings (blob directories) that are created dynamically - depend of supported types. What's more - I need this string value in couple of places, I don't want to duplicate it.
I would like them to be placed in some kind of configuration provider that builds the blob path string depending on some enum, for instance.
How to do it?

Answer 1

You can implement INameResolver to resolve QueueNames and BlobNames dynamically. You can add the logic to resolve the name there. Below is some sample code.
public class BlobNameResolver : INameResolver
{
public string Resolve(string name)
{
if (name == "blobNameKey")
{
//Do whatever you want to do to get the dynamic name
return "the name of the blob container";
}
}
}
And then you need to hook it up in Program.cs
class Program
{
// Please set the following connection strings in app.config for this WebJob to run:
// AzureWebJobsDashboard and AzureWebJobsStorage
static void Main()
{
//Configure JobHost
var storageConnectionString = "your connection string";
//Hook up the NameResolver
var config = new JobHostConfiguration(storageConnectionString) { NameResolver = new BlobNameResolver() };
config.Queues.BatchSize = 32;
//Pass configuration to JobJost
var host = new JobHost(config);
// The following code ensures that the WebJob will be running continuously
host.RunAndBlock();
}
}
Finally in Functions.cs
public class Functions
{
public async Task ProcessBlob([BlobTrigger("%blobNameKey%")] Stream blob)
{
//Do work here
}
}
There's some more information here.
Hope this helps.