How to share code in JavaScript Azure Functions?

Question

How can I share code (e.g. Mongo schema definitions) between files in an Azure function app?

I need to do this, as my functions require access to a shared mongo schema and models, such as this basic example:

var blogPostSchema = new mongoose.Schema({
  id: 'number',
  title: 'string',
  date: 'date',
  content: 'string'
});

var BlogPost = mongoose.model('BlogPost', blogPostSchema);

I've tried to add a "watchDirectories": [ "Shared" ] line to my host.json and in that folder added an index.js containing the above variable definition but this doesn't seem to be available to the other functions.

I simply get a Exception while executing function: Functions.GetBlogPosts. mscorlib: ReferenceError: BlogPost is not defined.

I've also tried explitely requireing the .js file, but this seems not to be found. It could be I just got the path wrong.

Does anyone have an example or tips on how to share .js code between azure functions?

Answer 1

I fixed this issue by doing the following steps:

1. Add a line to the root hosts.json to watch a shared folder. "watchDirectories": [ "Shared" ]
2. In the shared folder, added a blogPostModel.js file containing the following schema/model definition and export

shared\blogPostModel.js

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var blogPostSchema = new Schema({
    id: 'number',
    title: 'string',
    date: 'date',
    content: 'string'
});
module.exports = mongoose.model('BlogPost', blogPostSchema);

3. In my function require the shared file with the following path: var blogPostModel = require('../Shared/blogPostModel.js');

I can then make a connection and interact with the model doing finds etc in each individual function.

This solution was composed from the following SO posts:

Azure Function in Node.js and shared files

Cannot overwrite model once compiled Mongoose