Connecting to a PostgreSQL database using Flexmonster Data Server

This tutorial describes how to connect to a PostgreSQL database using 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.

Prerequisites

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 PostgreSQL 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:

<fm-pivot 
 [toolbar]="true">
</fm-pivot>

In React

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

<FlexmonsterReact.Pivot
 toolbar={true}
/>

In Vue

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

<Pivot
 ref="pivot"
 toolbar>
</Pivot>

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 database.

Step 3. Add a new index

Now let’s create a new index for 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 Database.
Database type. Select the database. In this case, it should be PostgreSQL.
Connection string. Specify the connection string to your database here. Have a look at the examples of different connection strings for PostgreSQL.
Click Test to check whether the provided connection string is correct.
Query. Specify an SQL query to define the subset of data that the Data Server should fetch. The Query can contain a stored procedure.
Refresh time. It defines how often the Data Server should reload the data from the database. 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 PostgreSQL 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-database"
        }
    }
});

Note The index must match the name of the index defined in step 3 (e.g., "index-database").

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.

Note You can manage the cache size via the Cache size limit configuration.

Calling a stored procedure

Follow the steps below to call a stored procedure in the Data Server:

Step 1. Create a stored procedure.

Step 2. When adding a new index, call the stored procedure in the Query field:

call storedProcedure()

Learn more about calling stored procedures in PostgreSQL.

Note Stored procedures allow executing any valid SQL query from the Data Server. To avoid unauthorized access to the database, create a database user with read-only access rights and specify this user in the connection string.

What’s next?

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