How to Copy file from Azure Blob Storage Container to Cosmos Mongo DB Collections Dynamically using Azure Function App

Question

We have 11 JSON files in our azure blob storage container in a folder called jsonfiles, Let's assume the file names as (a.json, b.json, c.json, d.json, e.json, f.json, g.json, h.json, i.json, j.json, k.json).

Similarly, we have 11 Cosmo Mongo DB Collection, assume the collection name as below [ a, b, c, d, e, f, g, h, I, j, k].

I need to copy/upload (a.json file to 'a' collection), (b.json to 'b' collection), (c.json to 'c' collection), (d.json to 'd' collection), (e.json to 'e' collection), (f.json to 'f' collection), (g.json to 'g' collection), (h.json to 'h' collection), (i.json to 'i' collection), (j.json to 'j' collection), (k.json to 'k') collection.

I need to Achieve the above requirement through Azure Function App. If Someone is well and good with Azure Function, Please Explain in detailed how to achieve this.

Detailed Explanation is Much Appreciated. Thank You in Advance.

Answer 1

• to download the blob, you will need a blob service client,container clientand a blobclient . Then we can use downloadtofile function to download the file.

• the downloadtofile function will take a file location as input and will write data from the blob to a file with the same name is blob.

• There must exist a file with same name is blob.

• Similarly, now you would need a MongodbClient to connect to database and then we can read file which are downloaded and add them in documents which are Json objects and then use insertOne as to upload the documents with our Json file to azure cosmos db mongo db.

• Here I am downloading three files and uploading them to azure

complete code:

// Dependencies

const { BlobServiceClient } = require("@azure/storage-blob");
const { MongoClient } = require('mongodb');
const  fs = require('fs');
const { ObjectID } = require("bson");

  

const  container_name = "test";
const  connblob = "<Connection String of Storage Account>";

  
  

module.exports = async  function (context, req) {

/// Hepls in connecting to Database
const  client = new  MongoClient("< Connectiom String of azure cosmosdb mongodb>");

  
// connecting to blob storage
var  blob_service_client = BlobServiceClient.fromConnectionString(connblob);

// refence of container

var  container_client = blob_service_client.getContainerClient(container_name);

  
  
// Reference of perticular blobs

var  blob_client1 = container_client.getBlobClient("a.json");

// download the blob

await  blob_client1.downloadToFile("./blobs/a.json");

  

var  blob_client2 = container_client.getBlobClient("b.json");

await  blob_client2.downloadToFile("./blobs/b.json");

  
  

var  blob_client3 = container_client.getBlobClient("c.json");

await  blob_client3.downloadToFile("./blobs/c.json");

  
// connection to databse
await  client.connect();

// creating the database

const  databse = client.db("test");

// creating collenctions

const  collection1 = databse.collection("a");

const  collection2 = databse.collection("b");

const  collection3 = databse.collection("c");

  
// Reading files

const  f1 = fs.readFileSync('./blobs/a.json', 'utf-8')

const  f2 = fs.readFileSync('./blobs/b.json', 'utf-8')

const  f3 = fs.readFileSync('./blobs/c.json', 'utf-8')

  
  // creating documents

var  t1 = {

_id:ObjectID("123456789012")

}

  

var  t2 = {

_id:ObjectID("212345678909")

}

  

var  t3 = {

_id:ObjectID("312345678901")

}

  // adding files to documents

t1["file"] = f1;

t2["file"] = f2;

t3["file"] = f3;

  // adding documents to mongodb

collection1.insertOne(t1);

collection2.insertOne(t2);

collection3.insertOne(t3);

  
  

context.res = {

// status: 200, /* Defaults to 200 */

body:  "responseMessage"

};

  
  

}