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  1. API reference
  2. Welcome
    1. Introduction
    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. Angular
      1. Integration with Angular
      2. Flexmonster usage in Angular
    3. React
      1. Integration with React
      2. Flexmonster usage in React
    4. Vue
      1. Integration with Vue 2
      2. Flexmonster usage in Vue 2
      3. Integration with Vue 3
      4. Flexmonster usage in Vue 3
    5. Other integrations
      1. Integration with Python
        1. Integration with Django
        2. Integration with Jupyter Notebook
      2. Integration with React Native
      3. Integration with Blazor
      4. Integration with AngularJS (v1.x)
      5. Integration with TypeScript
      6. Integration with R Shiny
      7. Integration with jQuery
      8. Integration with Ionic
      9. Integration with Electron.js
      10. Integration with Webpack
      11. 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. Managing data presentation in JSON
    3. CSV
      1. Connecting to CSV
      2. Connecting to CSV using Flexmonster Data Server
      3. Managing data presentation 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. Flexmonster Admin Panel Guide
      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. The Data Server as a console application
        1. Installing the Data Server as a console application
        2. Configurations reference
        3. Data sources guide
        4. Security and authorization guide
      8. 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
      4. Configuring the MongoDB Connector
    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. Connecting to other data sources
  5. Accessibility
    1. Accessibility overview
    2. Keyboard navigation
  6. Configuring the component
    1. Available tutorials
    2. Getting started with the report
    3. Configure the data source
      1. Data source
      2. Mapping
    4. Define which data to show
      1. Slice
      2. Custom sorting
      3. Calculated values
    5. Manage Flexmonster’s functionality
      1. Options
      2. Configuring global options
    6. Format fields
      1. Number formatting
      2. Date and time formatting
      3. Conditional formatting
  7. Saving component configs
    1. Available tutorials
    2. Save and restore the report
    3. Share the report
    4. Export and print
  8. 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
  9. 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
  10. 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
  11. Updating to the latest version
    1. Updating to the latest version
    2. Release notes
    3. Migration guide from 2.8 to 2.9
    4. Migration guide from 2.7 to 2.8
    5. Migration guide from 2.6 to 2.7
    6. Migration guide from 2.5 to 2.6
    7. Migration guide from 2.4 to 2.5
    8. Migration guide from 2.3 to 2.4
    9. Migration guide from 2.2 to 2.3
  12. Flexmonster CLI Reference
    1. Overview
    2. Troubleshooting the CLI
    3. flexmonster create
    4. flexmonster add
    5. flexmonster update
    6. flexmonster version
    7. flexmonster help
  13. 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 webpage

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

In pure JavaScript

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

let 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 -r

The flexmonster add fds command does the following:

  • Downloads the .zip archive with Flexmonster Data Server.
  • Automatically unpacks the files in the current folder. As a result, the flexmonster-data-server/ folder will appear in your working directory.

The -r option, which is short for --run, installs the Data Server as a Windows/Unix service and then runs it. Besides, it installs and runs Flexmonster Admin Panel – a graphical user interface for the Data Server.

Now follow the steps below to connect the Data Server to your JSON file.

Step 3. Add a new index

Now let’s create a new index for the file with your data. 

Open Flexmonster Admin Panel and go to Indexes > Add New Index. Then, fill in the following fields:

  • Name. This field defines the index name. It will be used to configure the connection on the client side.
  • Type. This drop-down menu contains possible data source types. In this case, select JSON.
  • Path to file. In this field, specify the path to the file with your data. You can click the folder icon to choose the needed file using Explorer.
  • Refresh time. It defines how often the Data Server should reload the data from the file. The refresh time should be specified in minutes.
    By default, the refresh time is 0, which means the Data Server will not reload the data.

Your configurations should look similar to the following:

Sample configuration of a JSON index

When the index configuration is complete, click Create. The index will be automatically added to your index pool.

Step 4. 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 3 (e.g., "index-json").

When Flexmonster Pivot requests the data, Flexmonster Data 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 Cache size limit configuration.

What’s next?

You may be interested in the following articles: