Velocity Overview

Yespo uses Velocity — an open-source templating language — to work with dynamic data in messages and workflows.

With Velocity, you can insert contact field values into content, render event data passed through a triggered workflow, apply conditions, and use values returned from external sources.

Where Velocity Gets Data

Velocity works with data already available in Yespo: contact fields, event data, and external sources.

For the full data model, source availability, and precedence rules, see the Overview.

Preprocessor

For more advanced personalization tasks — product recommendations, random selections, targeted offers for different segments — Yespo offers the preprocessor. This is a separate mechanism for forming dynamic content based on pre-prepared data that extends Velocity's capabilities.

For details, see the Preprocessor article.

In This Section

• Contact Field Variables Reference — variables for contact fields, fallback patterns, and examples.
• Dynamic Content Preview in Short-Form Messages — how to preview messages with contact data and test JSON, and check the actual SMS length.
• Velocity in Messages — how to use variables, objects, arrays, loops, and conditions in message templates.
• Velocity in Workflows — how to transform values, branch by data, use webhooks, and save results to contact fields.
• Preprocessor — personalization based on pre-prepared data: product recommendations, random selections, Key and Random types.
• Velocity Reference — full syntax reference: variables, arrays, loops, conditions, operators, dates, and data access examples.
• Testing & Troubleshooting Velocity — how to preview dynamic content, inspect available context, and fix common substitution issues.

• Dynamic Links in Email — add dynamic URLs to email buttons using contact fields and event parameters.