Postback Request
In Salesforce Visualforce, an HTTP POST request sent back to the server when a user interacts with a form element on a Visualforce page, triggering server-side controller actions and potentially re-rendering page components.
Definition
In Salesforce Visualforce, an HTTP POST request sent back to the server when a user interacts with a form element on a Visualforce page, triggering server-side controller actions and potentially re-rendering page components.
In plain English
“A Postback Request in Visualforce is an HTTP POST request sent back to the server when a user interacts with a form element on a Visualforce page. It triggers server-side controller actions and can re-render parts of the page based on the response.”
Worked example
On a Visualforce page at Yarmouth Trading, a user clicks the "Recalculate Tax" button on a Quote-edit form. The click fires a Postback Request - an HTTP POST to the same Visualforce page URL, including all the form's current field values. The server-side Visualforce Controller receives the postback, runs the recalculate-tax Apex method, updates the controller's Tax property, and responds with a re-rendered version of the page reflecting the new tax. The user sees the page update without a full navigation. Postback Requests are how Visualforce maintains form state across server-side action invocations.
Why Postback Request matters
In Salesforce Visualforce, a Postback Request is an HTTP POST request sent back to the server when a user interacts with a form element on a Visualforce page, triggering server-side controller actions and potentially re-rendering page components. Postbacks are how Visualforce pages handle user interactions: clicking a button, changing a field value, or submitting a form sends data back to the server, which processes the action and returns updated page content.
Postbacks are a core concept in Visualforce, which uses a server-side rendering model where most logic happens on the server. This contrasts with modern Lightning Web Components, which run more logic in the browser and use AJAX-style communication for server interaction. Knowing about postbacks matters for working with Visualforce pages and for understanding why Visualforce performance characteristics differ from LWC. Modern Salesforce development typically uses LWC for new work, with Visualforce remaining for legacy support.
How organizations use Postback Request
Maintains legacy Visualforce pages using postback patterns while building new functionality in LWC.
Migrated from Visualforce postback-heavy pages to LWC for better performance and modern user experience.
Trains developers on Visualforce concepts including postbacks for understanding legacy code.
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
Test your knowledge
Q1. What is a Postback Request?
Q2. What triggers a postback?
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