Expression Library API

Built-in and custom expression templates used in pipeline operator logic stages. Custom expressions are tenant-scoped.

Field	Value
Port	50033
Base Path	/api/v1
Framework	Spring Boot 3.2.0, Java 21
OpenAPI	3.0.1
Spec	Expression_LIbrary.json
Swagger UI	/swagger-ui.html
Database	PostgreSQL (daitics)

---

Authentication

Config	Value
Method	OAuth2 JWT (Keycloak)
Multi-tenancy	tenant_id from JWT — custom expressions scoped per tenant
CORS	localhost:3000, localhost:8080, *.daitics.com
Public endpoints	/actuator/health, /actuator/info, /v3/api-docs/**, /swagger-ui/**

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System Expressions (Read-Only)

Built-in expressions available to all tenants.

Method	Path	Description	Query Params
GET	/api/v1/expressions	List system expressions	category, operatorType, search, tags[]
GET	/api/v1/expressions/{id}	Get by integer ID	—
GET	/api/v1/expressions/by-expression-id/{expressionId}	Get by string ID (e.g., CONCAT)	—

ExpressionDTO

{
  "id": 1,
  "expressionId": "CONCAT",
  "name": "CONCAT",
  "category": "STRING",
  "operatorTypes": ["TRANSFORM", "FILTER"],
  "description": "Concatenates multiple strings...",
  "syntax": "CONCAT(str1, str2, ...strN, separator)",
  "example": "CONCAT(firstName, \" \", lastName) -> \"John Doe\"",
  "parameters": [ ... ],
  "returnType": "STRING",
  "tags": ["string", "text", "concatenation"],
  "isActive": true
}

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Custom Expressions (Tenant-Scoped CRUD)

Method	Path	Description	Status Codes
GET	/api/v1/expressions/custom	List tenant's custom expressions	200
POST	/api/v1/expressions/custom	Create custom expression	201, 400, 409
GET	/api/v1/expressions/custom/{id}	Get by UUID	200, 404
PUT	/api/v1/expressions/custom/{id}	Update (version increments on body change)	200, 400, 404, 409
DELETE	/api/v1/expressions/custom/{id}	Soft delete	204, 404
POST	/api/v1/expressions/custom/{id}/use	Increment usage count	200

CreateCustomExpressionRequest

Field	Type	Required	Validation
expressionId	string	Yes	3–100 chars, ^[a-z0-9_]+$
name	string	Yes	3–100 chars, starts with letter
description	string	No	Max 1000 chars
category	string	Yes	Max 50 chars
operatorTypes	string[]	No	—
parameters	object (JSONB)	Yes	—
body	string	Yes	1–5000 chars
returnType	string	Yes	See return types below
tags	string[]	No	—
isTemplate	boolean	No	Default false

Return Types: STRING INTEGER DECIMAL BOOLEAN DATE TIMESTAMP ARRAY JSON ANY

---

Response Envelope

{
  "success": true,
  "data": { ... },
  "error": {
    "code": "string",
    "message": "string",
    "details": { ... }
  },
  "timestamp": "2025-11-11T10:30:00"
}

Error Codes

Code	HTTP	Meaning
RESOURCE_NOT_FOUND	404	Expression not found
VALIDATION_ERROR	400	Input validation failed
DATA_INTEGRITY_VIOLATION	409	Duplicate expression_id
INTERNAL_SERVER_ERROR	500	Unexpected error

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Database Tables

Table	Key	Scope	Indexes
expressions_library	id (SERIAL), unique expression_id	System-wide	11 (B-tree + GIN for arrays/JSONB/FTS)
custom_expressions	id (UUID)	Per-tenant (tenant_id)	11 (B-tree + GIN)

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Health & Actuator

Path	Auth	Description
/actuator/health	Public	DB, disk, liveness, readiness
/actuator/info	Public	Service info
/actuator/metrics	Auth required	Prometheus-style metrics

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Frontend Integration

File	Purpose
services/expression-library/expression-library.service.ts	Expression fetching & evaluation
services/expression-library/useExpressions.ts	React Query hook
types/expression-library-api.types.ts	TypeScript types