How to process a file using Azure Function

Question

I would like to process an input file and output it to some location for ex. FTP or Azure storage. I am trying to use Azure Function with SaasFile input/output. I am getting below error:

2016-07-14T00:44:53 Welcome, you are now connected to log-streaming service. 2016-07-14T00:45:00.580 Script for function 'HttpTriggerCSharp1' changed. Reloading. 2016-07-14T00:45:00.580 Compiling function script. 2016-07-14T00:45:00.721 run.csx(24,25): error CS0622: Can only use array initializer expressions to assign to array types. Try using a new expression instead. 2016-07-14T00:45:00.721 Compilation failed.

Here is my function signature:

public static async Task<HttpResponseMessage> Run(HttpRequestMessage req, string output, TraceWriter log)

Bindings:

{
  "bindings": [
    {
      "authLevel": "function",
      "name": "req",
      "type": "httpTrigger",
      "direction": "in"
    },
    {
      "name": "res",
      "type": "http",
      "direction": "out"
    },
    {
      "type": "apiHubFile",
      "name": "output",
      "path": "path/{file}",
      "connection": "ftp_FTP",
      "direction": "out"
    }
  ],
  "disabled": false
}

I think I am missing something in Run signature. I couldn't find it on Azure documentation.

I need help figure out how to process using FTP and Azure Storage. Thanks for your help.

Answer 1

You don't really need a http trigger for this. Here is an example which watches a folder(input-cs) for new files in dropbox and copies the file to a folder (output-cs) in googledrive:

using System;

public static void Run(string input, out string output, TraceWriter log)
{
    output = input;
}

bindings:

{

 "bindings": [
    {
      "type": "apiHubFileTrigger",
      "name": "input",
      "direction": "in",
      "path": "input-cs/{name}",
      "connection": "dropbox_DROPBOX"
    },
    {
      "type": "apiHubFile",
      "name": "output",
      "direction": "out",
      "path": "output-cs/{name}",
      "connection": "googledrive_GOOGLEDRIVE"
    }
  ],
  "disabled": false
}

Hope it helps!

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Thank you!!

Answer 2

Good news.. External File trigger is available for Azure functions.

If you want to process file in an external FTP folder, create a FTP connection first and then use it.

So your bindings array for FTP connection in function.json shown below.

{
  "bindings": [
    {
      "type": "apiHubFileTrigger",
      "name": "inputFile",
      "direction": "in",
      "path": "input-cs/{name}",
      "connection": "ftp_FTP"
    },
    {
      "type": "apiHubFile",
      "name": "$return",
      "direction": "out",
      "path": "output-cs/{name}",
      "connection": "ftp_FTP"
    }
  ],
  "disabled": false
}

In the above JSON,

path

Represents the path of the file to be processed. So in above case, azure function will be triggered when a file is added/modified in input-cs folder.

connection

Represents the External File connector name.

Comments

Thank you :)