Output bindings not picked up or present in Javascript Azure Functions

Question

I'm having a bit of difficulty getting my simple Azure Function to dump a JSON payload into a CosmosDB. Here is the desired setup:

[HTTP TRIGGER] -> [JS FUNCTION] -> [INSERT JSON TO COSMOS DB]

I've added a cosmosDB output binding via Integrate in the web console

I know this part works because it will auto-create the collection upon running.

However, this is where my success ends.

I've included my code here. Maybe there is something obvious that I have missed:

function.json

{
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    },
    {
      "type": "documentDB",
      "name": "outputDocument",
      "databaseName": "outDatabase",
      "collectionName": "MyCollection",
      "createIfNotExists": true,
      "connection": "mydocdb_DOCUMENTDB",
      "direction": "out"
    }
  ],
  "disabled": false
}

index.js

module.exports = function (context, req) {
    context.log('JavaScript HTTP trigger function processed a request.');

    context.bindings.outputDocument = {test: "hello world"}
    context.done();
};

snippet output of context.log(context) I've also peeked into the context variables, and it seems that the outbund bindings not there. I would have expected to see outputDocument here:

bindings: 
   { req: 
      { originalUrl: 'https://log-ugly-url-here',
        method: 'POST',
        query: [Object],
        headers: [Object],
        body: [Object],
        params: {},
        rawBody: '{\n    "name": "Azure"\n}' } },
  bind: [Function],

Executing this function in the portal gets a 200 OK, but no values show up in my cosmosdb collections.

No errors are shown anywhere.

Can anyone see what I might have missed?

Updates It was recommended that I try to use JSON.stringify() around the payload, per this document:

context.bindings.outputDocument = JSON.stringify({test: "hello world"});

However, this has not resolved the issue. I've noticed that the documentation under the binding config sections does not recommend this strategy.

Update - Nov. 8, 2017 (10:12 AM)

I was using the Data Explorer blade in azure to see if there were results in my collections. I decided to use Robo 3T Mongo client. Now, when I query the collection I get the following error:

Error: error: {
    "_t" : "OKMongoResponse",
    "ok" : 0,
    "code" : 1,
    "errmsg" : "Unknown server error occurred when processing this request.",
    "$err" : "Unknown server error occurred when processing this request."
}

I tried to look at the logs for this cosmosdb, but no errors show up.

Based on the example in this doc it appears the DocDB binding from javascript expects a string (in a JSON.stringify()). Let me know if that works. doc here — jeffhollan
Thanks for the input. Unfortunately that did not work either. I'm updating the original question with different strategies until we get this solved. — Sam Texas
Your initial code works just fine for me, I got the "hello world" document inserted. context.log(context) is the same, so it's not a problem. Just in case: the document gets auto-generated ID, maybe you just don't see it? — Mikhail Shilkov
@Mikhail thanks for trying it out. I've updated the question again with output from my mongo client (Robo 3T). — Sam Texas
Possible duplicate of Azure Function with Cosmos MongoDB integration not saving — Sam Texas

Chris Katz Chris Katz · Accepted Answer · 2018-02-07T17:32:33

I ran into this as well. Kept banging my head until I saw this:

https://docs.microsoft.com/en-us/azure/azure-functions/functions-integrate-store-unstructured-data-cosmosdb

“At this time, the Azure Cosmos DB trigger, input bindings, and output bindings work with SQL API and Graph API accounts only“

Looks like there is a bug in Azure that accidentally corrupts the database.

Output bindings not picked up or present in Javascript Azure Functions

1 Answers