PLV8 is a procedural language extension for PostgreSQL, allowing developers to write stored procedures and functions in JavaScript. One common question among users and developers is whether PLV8 can make HTTP calls to external servers. In this article, we will explore this topic, clarify some concepts, and provide insights into how you can use PLV8 for HTTP requests.
Rephrasing the Problem
Many developers using PostgreSQL with PLV8 wonder if they can leverage PLV8's capabilities to make network calls, specifically HTTP requests, to other servers directly from their database. This would potentially allow for more dynamic data handling and integration with external APIs without the need for additional middleware.
The Scenario
Let's consider a scenario where you have a PostgreSQL database that stores user information and you want to enhance your application by fetching additional data from an external API. For instance, you might want to pull the latest weather data based on user location or get updated stock prices. You might think to implement this functionality using PLV8, which runs JavaScript within PostgreSQL.
Here’s a simple original code example that attempts to make an HTTP call in PLV8:
CREATE OR REPLACE FUNCTION fetch_weather_data(city TEXT)
RETURNS TEXT AS $
var url = "http://api.weatherapi.com/v1/current.json?key=YOUR_API_KEY&q=" + city;
var response = plv8.http_get(url);
return response;
$ LANGUAGE plv8;
In this example, we want to fetch weather data for a specified city by making an HTTP GET request to the Weather API.
Analysis and Clarification
Does PLV8 Support HTTP Calls?
The straightforward answer is that PLV8 does not natively support making HTTP calls as part of its core functionality. The PLV8 extension primarily allows JavaScript execution, but it lacks built-in libraries or functions that support network requests.
However, there are some workarounds you might consider:
-
Using PL/pgSQL with External Libraries: Instead of PLV8, you can use PostgreSQL's support for different procedural languages like PL/pgSQL in conjunction with external tools such as
pg_cronor background workers. These can schedule or execute tasks that perform HTTP calls outside of the database environment. -
JavaScript Outside PLV8: You can execute your JavaScript in a Node.js environment or similar server-side scripting platforms. In this case, your PostgreSQL database can communicate with your application layer, which handles HTTP calls.
-
HTTP Extensions: Some PostgreSQL extensions such as
pg_httpallow you to make HTTP requests directly from SQL. You can execute functions to perform GET or POST requests, returning responses into your PostgreSQL environment.
Example of Alternative Approach
An alternative to using PLV8 for HTTP requests is the pg_http extension. Here is a brief example of how you might use it:
CREATE EXTENSION pg_http;
SELECT *
FROM http_get('http://api.weatherapi.com/v1/current.json?key=YOUR_API_KEY&q=London');
This command performs a GET request directly from PostgreSQL, allowing you to retrieve data without needing PLV8.
Conclusion
While PLV8 offers powerful capabilities for JavaScript execution within PostgreSQL, it does not directly support making HTTP calls to external servers. For developers looking to make HTTP requests from PostgreSQL, alternative approaches, including using external libraries or different procedural languages, are more suitable.
Additional Resources
For those looking to expand their knowledge on this topic, consider these resources:
By understanding the limitations of PLV8 and exploring alternative methods, developers can effectively integrate external API data into their PostgreSQL applications.
This article should help clarify the capabilities of PLV8 concerning HTTP requests, providing readers with actionable insights and additional resources.
