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  1. API reference
  2. Welcome
    1. Getting started
    2. Get Flexmonster
    3. Quick start
    4. System requirements
    5. Troubleshooting
    6. Managing license keys
    7. Migrating from WebDataRocks to Flexmonster
  3. Integration with frameworks
    1. Available tutorials
    2. Integration with Angular
    3. Integration with React
    4. Integration with Vue
    5. Other integrations
      1. Integration with Python
        1. Integration with Django
        2. Integration with Jupyter Notebook
      2. Integration with React Native
      3. Integration with AngularJS (v1.x)
      4. Integration with TypeScript
      5. Integration with R Shiny
      6. Integration with jQuery
      7. Integration with Ionic
      8. Integration with Electron.js
      9. Integration with Webpack
      10. Integration with RequireJS
  4. Connecting to Data Source
    1. Supported data sources
    2. JSON
      1. Connecting to JSON
      2. Connecting to JSON using Flexmonster Data Server
      3. Data types in JSON
    3. CSV
      1. Connecting to CSV
      2. Connecting to CSV using Flexmonster Data Server
      3. Data types in CSV
    4. Database
      1. Connecting to SQL databases
      2. Connecting to a MySQL database
      3. Connecting to a Microsoft SQL Server database
      4. Connecting to a PostgreSQL database
      5. Connecting to an Oracle database
    5. Flexmonster Data Server
      1. Introduction to Flexmonster Data Server
      2. Getting started with Flexmonster Data Server
      3. Configurations reference
      4. Data sources guide
      5. Security and authorization guide
      6. The Data Server as a DLL
        1. Getting started with the Data Server as a DLL
        2. Referencing the Data Server as a DLL
        3. Implementing the API controller
        4. Implementing the server filter
        5. Implementing the custom parser
        6. DLL configurations reference
        7. The controller's methods for request handling
      7. Troubleshooting the Data Server
    6. MongoDB
      1. Introduction to Flexmonster MongoDB Connector
      2. Getting started with the MongoDB Connector
      3. Embedding the MongoDB Connector into the server
    7. Microsoft Analysis Services
      1. Connecting to Microsoft Analysis Services
      2. Getting started with Flexmonster Accelerator
      3. Referencing the Accelerator as a DLL
      4. Configuring the authentication process
      5. Configuring a secure HTTPS connection
      6. Troubleshooting
    8. Custom data source API
      1. Introduction to the custom data source API
      2. A quick overview of a sample Node.js server
      3. A quick overview of a sample .NET Core server
      4. Implement your own server
        1. Implementing the custom data source API server
        2. Implementing filters
        3. Supporting more aggregation functions
        4. Supporting multilevel hierarchies
        5. Returning data for the drill-through view
        6. Testing your custom data source API server
    9. Elasticsearch
      1. Connecting to Elasticsearch
      2. Configuring the mapping
    10. Pentaho Mondrian
      1. Connecting to Pentaho Mondrian
      2. Getting started with the Accelerator
      3. Configuring Mondrian roles
      4. Configuring username/password protection
      5. Configuring a secure HTTPS connection
      6. Troubleshooting
    11. Connecting to other data sources
  5. Security
    1. Security in Flexmonster
    2. Security aspects of connecting to an OLAP cube
      1. Ways of connecting to an OLAP cube
      2. The data transfer process
      3. Data security
      4. Data access management
  6. Configuring report
    1. What is a report
    2. Data source
    3. Slice
    4. Options
    5. Mapping
    6. Number formatting
    7. Conditional formatting
    8. Set the report for the component
    9. Get the report from the component
    10. Date and time formatting
    11. Configuring global options
    12. Export and print
    13. Calculated values
    14. Custom sorting
  7. Charts
    1. Available tutorials
    2. Flexmonster Pivot Charts
    3. Integration with Highcharts
    4. Integration with amCharts
    5. Integration with Google Charts
    6. Integration with FusionCharts
    7. Integration with any charting library
  8. Customizing
    1. Available tutorials
    2. Customizing the Toolbar
    3. Customizing appearance
    4. Customizing the context menu
    5. Customizing the grid
    6. Customizing the pivot charts
    7. Localizing the component
  9. Updating to the latest version
    1. Updating to the latest version
    2. Release notes
    3. Migration guide from 2.7 to 2.8
    4. Migration guide from 2.6 to 2.7
    5. Migration guide from 2.5 to 2.6
    6. Migration guide from 2.4 to 2.5
    7. Migration guide from 2.3 to 2.4
    8. Migration guide from 2.2 to 2.3
  10. Flexmonster CLI Reference
    1. Overview
    2. Troubleshooting the CLI
    3. flexmonster create
    4. flexmonster add
    5. flexmonster update
    6. flexmonster version
    7. flexmonster help
  11. Documentation for older versions
Table of contents

Connecting to JSON using Flexmonster Data Server

In the previous article, we described how to connect the pivot table to the JSON data source. To gain even better performance while working with JSON datasets, use Flexmonster Data Server – a special server developed by Flexmonster. This server communicates with the client using the custom data source API – our custom communication protocol allowing you to retrieve already aggregated data from a server to Flexmonster Pivot.

Flexmonster Data Server has the following advantages:

  • Reduced browser’s memory usage. Since loading, processing, filtering, and aggregating of the data is made on the server side, Flexmonster Pivot gets the data in a ready-to-show format. Thus, the data is visualized faster, and the browser’s resources are used more efficiently.
  • Larger datasets. Despite Flexmonster Pivot can connect to a JSON file directly, the browser’s capability limits the size of a file (on average, up to 100 MB). Flexmonster Data Server can process files more than 1GB — the maximum file size depends on your RAM capacity and the number of unique members in the dataset.
  • Built-in security configurations. The Data Server allows establishing authorized access to data and managing security in a convenient way.
  • Cross-platform solution. The Data Server is available for popular operating systems: Windows, Ubuntu/Linux, and macOS.

Flexmonster Data Server supports only a specific JSON format – an array of objects, where each object is an unordered set of "key": "value" pairs. Here is an example:

       "Color" : "green",
       "Country" : "Canada",
       "State" : "Ontario",
       "City" : "Toronto",
       "Price" : 174,
       "Quantity" : 22


To download the Data Server, you will need Flexmonster CLI — a command-line interface tool for Flexmonster. If needed, install the CLI globally using npm:

npm install -g flexmonster-cli

After that, a new flexmonster command will be available in the console. Learn more about Flexmonster CLI and its commands in our documentation.

Now follow the steps below to connect to JSON using the Data Server.

Step 1. Embed the component into your web page

If Flexmonster is not yet embedded, set up an empty component in your web page:

In pure JavaScript

Complete the Quick start guide. Your code should look similar to the following example:

var pivot = new Flexmonster({
    container: "pivotContainer",
    toolbar: true

In Angular

Complete the Integration with Angular guide. Your code should look similar to the following example:


In React

Complete the Integration with React guide. Your code should look similar to the following example:


In Vue

Complete the Integration with Vue guide. Your code should look similar to the following example:


Step 2. Download Flexmonster Data Server

The previous step demonstrated how to configure Flexmonster Pivot. Now it’s time to set up Flexmonster Data Server.

Get the Data Server with the following CLI command:

flexmonster add fds

The flexmonster add fds command will download the .zip archive with Flexmonster Data Server and automatically unpack the files in the current folder. As a result, the flexmonster-data-server/ folder will appear in your working directory.

The Data Server can be configured in the flexmonster-data-server/flexmonster-config.json file. To learn more about all the available configurations, see the configurations reference.

To set configurations needed for the JSON data source, follow the steps below.

Step 3. Configure the data source type

Set the "Type" property in flexmonster-config.json to "json". It should be done as follows:

"DataSources": [
        "Type": "json"

Step 4. Define the dataset

Create an index for the file with your data. "Path" is the path to the file. For example:

"DataSources": [
        "Type": "json",
        "Indexes": {
            "index_json": {
                "Path": "./data/data.json"


In a similar way, additional indexes can be specified:

"Indexes": {
"index_json": {
    "Path": "./data/data.json"
   "another_index_json": {
       "Path": "./data/another_data.json"

"index_json" and "another_index_json" are dataset identifiers. They will be used to configure the data source on the client side.

Step 5. Run the server

Start Flexmonster Data Server by running the following command in the console:

on Windows


on macOS and Ubuntu/Linux


As soon as you start Flexmonster Data Server, it automatically preloads the data specified in the "Indexes" property. Thus, when Flexmonster Pivot requests the data, the server responds with already preloaded data.

The Data Server keeps preloaded data in the server’s RAM, so the number of indexes you can specify is limited by the server’s RAM amount.

Step 6. Configure the report

On the client side, the report should be configured as follows:

var pivot = new Flexmonster({
   container: "pivotContainer",
   toolbar: true,
   report: {
       dataSource: {
           type: "api",
           url: "http://localhost:9500",
         index: "index-json"


index must match the name of the index defined in step 4 (e.g., "index_json").

When Flexmonster Pivot requests the data, Flexmonster Data Server server sends the response and then caches it. In case the component sends the same request once again, the server responds with the data from its cache. The Data Server clears the cache when restarted.

The Data Server’s cache has a memory limit. When the cache does not have enough memory for a new response, the Data Server server deletes one of the previously cached responses.

You can manage the cache size via the “CacheSizeLimit” property.

What’s next?

You may be interested in the following articles: