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Data Contracts

Added in eventcatalog@3.8.0

Contracts define the schema structure for data product outputs. They provide clear expectations for downstream consumers and enable schema validation.

Your contracts can be any format you want (e.g JSON Schema, ODCS YAML, etc).

What are contracts?​

Contracts are schema specifications attached to data product outputs. They document the structure, types, and constraints of the data your product produces.

Contracts help teams:

  • Understand output data structures without inspecting code
  • Validate data against expected schemas
  • Catch breaking changes before deployment
  • Enable self-service data consumption

Supported formats​

EventCatalog supports any schema or specification format.

Adding contracts​

Contracts are defined in the outputs array of your data product frontmatter.

/data-products/PaymentAnalytics/index.mdx
---
id: payment-analytics
name: Payment Analytics
version: 1.0.0

outputs:
  - id: payment-analytics-db
    contract:
      path: payment-metrics-contract.json
      name: Payment Metrics Contract
      type: json-schema
---

Contract properties:

  • path is the file path relative to the data product directory
  • name is the display name shown in EventCatalog
  • type specifies the format (json-schema or odcs)

Viewing contracts​

EventCatalog provides a schema explorer for viewing contracts.

Use the <SchemaViewer /> component to display contracts in your documentation:

## Output Schema

<SchemaViewer file="payment-metrics-contract.json" />

Example

The schema explorer renders:

  • Interactive field navigation
  • Type information and constraints
  • Field descriptions
  • Required field indicators

Multiple contracts​

A single output can have multiple contracts for different tables or datasets.

outputs:
  - id: analytics-warehouse
    contract:
      path: fact-orders.json
      name: Fact Orders
      type: json-schema
  - id: analytics-warehouse
    contract:
      path: dim-customers.json
      name: Customer Dimension
      type: json-schema

Next steps​