javascript - Getting parameters from an Azure Function to use in function.json bindings

Question

I am new to Azure Functions and I'm having trouble with some of the basics, in particular how to pass parameter data to function.json so that I can write a blob to Azure Blob Storage using the Storage Connector.

My question is, how do I specify a parameter within the httpTrigger function that can be used by the outputBlobContents binding below?

My setup is pretty simple (but doesn't work yet):

---

function.json:

{
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "methods": [
        "post"
      ]
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    },
    {
      "type": "blob",
      "direction": "out",
      "name": "outputBlobContents",
      "path": "uploaded_files/{destinationFilename}",
      "connection": "MY_STORAGE"
    }
  ]
}

---

index.ts:

import { AzureFunction, Context, HttpRequest } from "@azure/functions"

const httpTrigger: AzureFunction = async function (context: Context, req: HttpRequest): Promise<void> {
    context.bindingData.destinationFilename = "testfile.pdf";
    context.bindings.outputBlobContents = context.req.body;
    const responseMessage = "uploaded file";

    context.res = {
        status: 201,
        body: responseMessage
    };

};

export default httpTrigger;

In my example code I am trying assign destinationFilename to the context.bindingData object, but this does not work. I've read through all the documentation but it's not very clear about what the bindingData object actually is or how named parameters work in general. How do I tell the blob storage connector where to store the file?

Answer 1

Simply put, any form of json input will be obtained as a parameter. Inside the function is impossible. If you want to use it inside the function, please choose to directly use the sdk of Azure Storage.

Since you use httptrigger, you can send a request body in json format, like this:

{
   "destinationFilename":"something"
}

After that, output binding can get the value.