joi

Validate incoming data against declared Joi schemas.

3|Updated Mar 8, 2026

Search Tags:#schema validation #custom extensions #joi #cross-field #request validation #api input #conditional validation

Ready to run

npx skills add https://github.com/avifenesh/glidemq-hapi --skill joi

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: joi
Source: https://github.com/avifenesh/glidemq-hapi/tree/main/.claude/skills/joi
Command: npx skills add https://github.com/avifenesh/glidemq-hapi --skill joi

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill includes references (resource) components.

What problem does it solve?

Joi helps you prevent invalid or malformed request data from breaking your application by enforcing a consistent schema at input boundaries.

Core Features & Use Cases

Schema-driven validation: Define objects, arrays, and primitive constraints so only expected shapes and values pass.
Cross-field and dynamic rules: Use references for relationships between fields and conditional logic with .when() to express real business rules.
Extensibility and better errors: Create custom types/extensions and tailor error messages for clearer feedback during API or form handling.

Quick Start

Use the joi skill to validate incoming input by defining a Joi.object() schema and calling validate(input) to obtain both the validated value and any structured error.

Frequently Asked Questions about joi

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

How do I validate API request body payloads against a schema?▼

To validate API request body payloads, define a Joi.object() schema and call validate() on the incoming input. This returns the validated value and structured validation errors, stopping invalid payloads early.

Can I create conditional cross-field validation rules for my API inputs?▼

Yes, conditional cross-field validation rules are supported by combining Joi.ref() to reference other fields with .when() workflows. This allows you to express dynamic business rules based on relationships between fields in your schema.

What is the best way to enforce custom domain rules and type extensions during input validation?▼

The best way to enforce custom domain rules is through schema extensibility. You can create custom types and extensions within your schemas, tailoring constraints and error messages for clearer feedback during API or form handling.

How do I handle immutable schema building for production service validation?▼

Immutable schema building involves declaring strict object, array, and primitive constraints without mutating the schema post-creation. Boundary validation is then applied via validate() or attempt() to ensure safe input processing in production services.

Does schema validation stop malformed request data before it breaks my application logic?▼

Yes, schema validation stops malformed request data at the input boundaries. By enforcing a consistent schema, only expected shapes and values pass, preventing invalid payloads from breaking your application logic and producing actionable errors.

What are the limitations of using cross-field validation with complex schemas?▼

Complex cross-field validation requires careful use of Joi.ref() and .when() workflows. Limitations arise when managing deeply nested conditional logic, requiring immutable schema building and precise boundary validation to avoid unpredictable rule evaluation.