Azure Functions C# Input binding not being generated is function.json

Question

I am using a QueueTrigger with the following signature:

public static void Run([QueueTrigger("tester")]string myQueueItem,[Blob("local/{queueTrigger}")]ICloudBlob myBlob,TraceWriter log)

The binding in function.json being generated is:

    "bindings": [
    {
      "type": "queueTrigger",
      "queueName": "tester",
      "connection": "AzureWebJobsStorage",
      "name": "myQueueItem"
    }
  ],

This doesn't work because it won't bind the appropriate blob as an in binding. If I manually edit the function.json it binds properly as it should:

"bindings": [
{
  "type": "queueTrigger",
  "queueName": "tester",
  "connection": "AzureWebJobsStorage",
  "name": "myQueueItem"
},
{
  "name": "myBlob",
  "type": "blob",
  "path": "local/{queueTrigger}",
  "direction": "in",
  "connection": "AzureWebJobsStorage"
}],

My question is how can I indicate that input binding in the C# code so the function.json gets generated appropriately? I know for output bindings you can decorate it with the out parameter, but what for the in? Is this a bug or am I missing something?

what version of the cli are you using? also which version of Microsoft.NET.Sdk.Functions are you using? you can find that in your csproj — ahmelsayed
– ahmelsayed, Commented Aug 30, 2017 at 16:38
I'm using Functions 1.0.0 and doing via Visual Studio tooling — Dexterity
– Dexterity, Commented Aug 30, 2017 at 18:25

Mike S · Accepted Answer · 2017-08-30 16:51:03Z

1

Is this authored via the Function VS tooling? That only generates a function.json describing the trigger [1]. The other bindings are read directly from the C# attributes, just like with WebJobs SDK.

The function.json that was autogenerated by the tool should also have a "configurationSource" : "attributes" property. That's what tells the Functions Runtime to read the bindings from the attributes. If that's missing, then it likely means you have pre-release tooling and need to update your CLI and Microsoft.NET.Sdk.Functions package.

Can you confirm that property is set?

Also, your "Run" method should have a [FunctionName] attribute on it.

[1] This was changed from the pre-release builds of tooling, see https://github.com/Azure/azure-webjobs-sdk-script/issues/1508

answered Aug 30, 2017 at 16:51

Mike S

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3 Comments

Dexterity Over a year ago

Yes I am using the attributes as you can see in the question and it has the configuration source. I also have a FunctionName attribute, I just omitted those things to show what was relevant. I'm using VS 15.3.2. Just updated the other day. To be clear, if I manually add the bindings to function.json in the bin it works as expected. If left to VS it does not work

Mike S Over a year ago

When it doesn't work - are you running it locally (via the CLI) or in Azure? If you're running in Azure on a version that's locked back to an older version (before the #1508 fix), then you'd see this failure.

Dexterity Over a year ago

I am running it locally. I managed to get it functioning properly by doing a repair on VS and re-installing the Functions tooling.

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