Expo Index

Expo guide

Expo checks model rules and reports each invalid property with a JSON Pointer. Most rules allow null; mark a value as required when the application must reject it.

Start with Validation with Expo for package installation and your first model.

Models and built-in rules

• Validation models: generate validation, run it explicitly, and choose required values.
• String rules: check length, whitespace, and built-in formats.
• Value rules: compare against constants and reject undefined enum values.
• Collections: constrain collection size and validate individual items.

Application rules

• Property comparisons: relate values through generated comparison attributes.
• Generated regex rules: define patterns and use their generated attributes.
• Custom rules: share attributes or write model-specific validation methods.
• Nested models: validate child objects and collections of children.

Validation output

• Errors and metadata: consume field failures, customize messages, and inspect rule metadata.

ASP.NET Core integration

• Expo validation: validate bound Partie requests and return HTTP failures.
• Expo OpenAPI: publish constraints in generated API documents.