Azure Blob Trigger - Dynamic BlobOutput Binding Name Based on Input Container - azure

Question

[Function("Function1")]
[BlobOutput("test-samples-output/{name}", Connection = "ConnectionString1")]
public string Run([BlobTrigger("test-samples-trigger/{name}", Connection = "ConnectionString1")] string myBlob,
string name, string blobTrigger)
{
_logger.LogInformation($"C# Blob trigger function Processed blob\n Name: {name} \n Data: {myBlob}");
return myBlob;
}
I have a blob trigger set to 'test-samples-trigger/{name}'. I want to set the BlobOutput to use the input container name '{input-container-name}-output/{name}'. Is there a way to set the BlobOuput string to dynamically point to this location?

Answer 1

After reproducing from my end, One way to achieve your requirement is to read variable using GetEnvironmentVariable where the value is read from local.settings.json. Below is the complete code that worked for me.
Function1.cs
using System;
using System.IO;
using System.Text;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Host;
using Microsoft.Extensions.Logging;
namespace FunctionApp13
{
public class Function1
{
[FunctionName("Function1")]
public void Run([BlobTrigger("samples-workitems/{name}", Connection = "connstr")]Stream myBlob,
[Blob("%outputContainer%/{name}", FileAccess.Write, Connection = "connstr")] Stream outputBlob,
string name, ILogger log)
{
log.LogInformation($"C# Blob trigger function Processed blob\n Name:{name} \n Size: {myBlob.Length} Bytes");
string outputContainer = Environment.GetEnvironmentVariable("outputContainer");
outputBlob.Write();
}
}
}
local.settings.json
{
"IsEncrypted": false,
"Values": {
"AzureWebJobsStorage": "<ConnectionString>",
"connstr": "<ConnectionString>",
"FUNCTIONS_WORKER_RUNTIME": "dotnet",
"outputContainer": "sample"
}
}
Results: