hapijs/joi
Joi
Joi is a JavaScript data validation library used to define schemas that validate, cast, and sanitize data objects. It functions as an object schema validator and parser, ensuring that input data matches specific types and formats before it is processed by an application.
The library features a conditional validation engine capable of dynamic schema enforcement, where validation logic and dependencies change based on the values of other keys within an object. It also serves as a data casting and sanitization tool, transforming input values into target types and removing sensitive keys from the resulting output.
Its broader capabilities include enforcing primitive and complex data types, validating specific string formats, and implementing custom validation logic. The system supports the definition of alternative schemas, the application of default values, and the enforcement of collection size limits.
The engine is extensible via a plugin system that allows for the injection of custom types and validation logic.
Features
- Data Validation Schemas - Implements a library for defining data structures and enforcing strict type safety and validation rules on input data.
- Data Type Coercion - Provides built-in mechanisms to coerce input values into target types before applying validation rules.
- Data Type Casting - Converts input values into required types, such as transforming numeric strings into numbers, before validation.
- Data Validation - Enforces type safety and constraints on JavaScript data objects before processing.
- Data Validation Libraries - Defines schemas to validate, cast, and sanitize data objects in JavaScript environments.
- Conditional Validation Rules - Enforces validation rules dynamically based on the values of other keys within the object.
- Conditional Enforcement - Applies conditional validation rules that change based on other values present in a data object.
- Type Conversion and Casting - Transforms input values into target types and applies default values during validation.
- Schema Tree Traversers - Traverses hierarchical schema structures using a depth-first process to validate nested objects and arrays.
- Data Validation and Sanitization - Converts input types to required formats and removes sensitive keys from validated objects.
- Context-Aware State Engines - Uses a shared internal context to evaluate rules based on the state of other object keys.
- Cross-Field Dependencies - Links validation rules to the values of other keys within the same object or context.
- Cross-Field Dependency Validations - Enforces complex relationships between object keys, such as requiring specific pairs or forbidding certain combinations.
- Data Schema Validation - Enforces type safety and data consistency by validating objects against predefined rules.
- Data Type Validation - Enforces that values match specific primitive or complex types according to a defined schema.
- Object Schema Definitions - Provides utilities for defining and manipulating complex object structures and their properties through a schema-based approach.
- Recursive Validation Engines - Employs a recursive engine to handle nested data structures by dispatching validation logic across type hierarchies.
- Dependency Resolution - Resolves dependencies between fields to conditionally update validation requirements based on runtime input.
- Length Constraints - Constrains the number of items in arrays or keys in objects using length requirements.
- Complex Data Modeling - Defines strict relationships and dependencies between fields in large objects to maintain integrity.
- Alternative - Supports flexible input types by matching values against multiple possible schema definitions.
- Fluent Interface Patterns - Implements a fluent interface pattern for defining complex validation schemas via method chaining.
- Input Sanitization - Cleans and transforms raw input values by casting types and removing sensitive keys.
- Format Validators - Enforces specific string patterns for common formats like emails, URIs, and ISO dates.
- Custom Validation Extensions - Allows the addition of user-defined methods to base schema types to implement domain-specific validation logic.
- Custom Validation Rules - Provides a framework for extending validation logic with custom, domain-specific checks.
- Schema Default Values - Assigns fallback values to fields when input data is missing or undefined.
- Extensible Plugin Architectures - Features an extensible architecture that allows the injection of custom types and logic via plugins.
- Request Validation - Validates incoming HTTP request bodies and parameters to ensure data integrity.
- Data Utilities and Libraries - Powerful data validation library for JavaScript.
- Data Validation - Object schema description and validation language.
