1.Embedding the MongoDB Connector into the server

We launched the sample GitHub project demonstrating the basics of using the Flexmonster MongoDB Connector in the previous guide. To have a better understanding of how the Connector works, consider completing the guide. This tutorial describes how to embed the Connector into a server.

To fetch data from a database and pass that data to the component, the Connector needs a mediator between itself and Flexmonster. Your server is the mediator, and its task is handling Flexmonster’s requests and passing them to the Connector in the acceptable form. The server has to be configured properly to complete this task.

All requests have index and type properties in the request body. There are 4 types of requests that can be distinguished by the URL path and type value:

<url>/handshake (optional) – The first (handshake) request to establish a connection between the client and server sides.
<url>/fields – Request for all fields with their types (i.e. meta-object or schema).
<url>/members – Request for all members of the field.
<url>/select – Request for the data.

The Connector has three methods to handle /fields, /members, and /select requests. See the documentation to learn more about these methods.

The following guide will walk you through the process of server configuration.

Step 1. Set up an empty component in your HTML page. If Flexmonster is not yet embedded – return to the Quick start guide. Your code should look similar to the following example:

<div id="pivotContainer">The component will appear here</div>
<script src="flexmonster/flexmonster.js"></script>
<script>
var pivot = new Flexmonster({
       container: "pivotContainer",
       toolbar: true,
       licenseKey: "XXXX-XXXX-XXXX-XXXX-XXXX"
   });
</script>

Note that licenseKey is your license or trial key, so replace XXXX-XXXX-XXXX-XXXX-XXXX with an actual key. If you don’t have a license key, get a trial key here.

Step 2. In report.dataSource, define these parameters to connect to your server:

<div id="pivotContainer">The component will appear here</div>
<script src="flexmonster/flexmonster.js"></script>
<script>
var pivot = new Flexmonster({
       container: "pivotContainer",
       toolbar: true,
       report: {
           dataSource: {
               type: "api",
               url: "<url>",
               index: "your-collection-name"
           }
       },
       licenseKey: "XXXX-XXXX-XXXX-XXXX-XXXX"
   });
</script>

Here, url is the path to your API endpoints (e.g. "http://localhost:9204/mongo"), and index is your collection’s name. index will be sent with each request.

At this step, as the back-end isn’t configured yet, you won’t see any data in the pivot if you open it in a browser.

In the next steps, you will start configuring the server.

Step 3. Install the Flexmonster MongoDB Connector and MongoDB driver:

npm install flexmonster-mongo-connector
npm install mongodb

Step 4. All the requests routing will be implemented in a separate .js file (e.g. mongo.js). At this step, include the .js file (e.g. mongo.js) into your server. Then all the requests coming to <url> will be handled by the separate module (in this case, the <url>/mongo path is used):

app.use('/mongo', require('./mongo.js'));

Now, all the requests sent to <url> (in this case,<url>/mongo) will be processed by the mongo module.

However, the code isn’t working at the current step since you haven’t defined the mongo.js file properly.

Note: If Flexmonster Pivot Table is running on a different server, enable CORS.

Step 5. In the mentioned in the previous step JavaScript file (e.g. mongo.js), include the following libraries:

const mongo = require('express').Router();
const mongodb = require("mongodb");
const fm_mongo_connector = require("flexmonster-mongo-connector");

Step 6. Then set up a connection with your MongoDB database and define the Connector:

let dbo = null;
let _apiReference = null; // it’ll be the Connector instance

mongodb.MongoClient.connect("mongodb://read:only@olap.flexmonster.com:27017", {
    useNewUrlParser: true
    }, (err, db) => {
        if (err)
            throw err;
        dbo = db.db("flexmonster");
        _apiReference = new fm_mongo_connector.MongoDataAPI();
});

Step 7. Export the mongo module so the server can use it:

// requests handling functions will appear here
module.exports = mongo;

Step 8. This step is optional as it describes the handling of a /handshake request, which is also optional. Even if the server side does not handle it, the Flexmonster component will proceed to the next request.

The/handshake request is used to establish a connection between the client and server sides and exchange some basic information. It can be handled this way:

mongo.post("/handshake", async (req, res) => {
     // do nothing
     res.status(200).send();
});

Step 9. The next request you have to handle is a /fields request, and it is sent to <url>/fields. It can be handled this way:

mongo.post("/fields", async (req, res) => {
    try {
        const result = await _apiReference.getSchema(dbo, req.body.index);
        res.json(result.toJSON());
    } catch (err) {
      //your error handler
    }
});

When Flexmonster Pivot Table successfully receives the response to the /fields request, it shows the Field List with all available fields. To see the list, open the HTML page configured in step 2 in a browser.

To learn more about the getSchema method, see this page.

Step 10. The next request to handle is the request for the field’s members that is sent to <url>/members. It can be handled this way:

mongo.post("/members", async (req, res) => {
    try {
        const result = await _apiReference.getMembers(dbo, req.body.index, req.body.field, { page: req.body.page, pageToken: req.body.pageToken });
        res.json(result);
    } catch (err) {
      //your error handler
    }
});

Now in the Field List, you will be able to select a string field for rows or for columns and retrieve its members.

To learn more about the getMembers method, see this page.

Step 11. When a field is selected for rows and/or columns and a numeric field is selected for measures in the Field List, the /select request is sent to the endpoint <url>/select. It can be handled this way:

mongo.post("/select", async (req, res) => {
    try {
        const result = await _apiReference.getSelectResult(dbo, req.body.index, req.body.query,{ page: req.body.page, pageToken: req.body.pageToken });
        res.json(result);
    } catch (err) {
      //your error handler
    }
});

When Flexmonster successfully receives the response to this kind of /select request, the pivot table with the received data is shown.

To learn more about the getSelectResult method, see this page.

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1.Embedding the MongoDB Connector into the server

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