validate

Validates accumulator properties against JSON Schemas compiled at factory time using AJV. Supports body, query parameter, and route parameter schemas. Includes ajv-formats for standard format keywords (email, uri, date-time, uuid, etc.) out of the box.

Pipeline stage: Validation (after body() and url())

Import

import { validate } from "@centralping/ergo";

Options

The validate() factory accepts two arguments: a schemas object and an options object — validate(schemas, options).

Schemas (first argument)

Property	Type	Default	Description
body	object	—	JSON Schema for the parsed request body
query	object	—	JSON Schema for query parameters
params	object	—	JSON Schema for route path parameters

These are direct properties of the first argument, not nested under a wrapper key. For example: validate({body: schema}), not validate({schemas: {body: schema}}).

Unrecognized keys warning

Passing unrecognized keys (e.g. validate({schemas: {body: ...}})) emits a one-time ERGO_VALIDATE_UNKNOWN_KEY process warning. The recognized keys are body, query, and params only.

Options (second argument)

Property	Type	Default	Description
formats	boolean | string[] | object	all standard	ajv-formats configuration

formats Values

Value	Behavior
undefined or true	All standard formats enabled
false	Formats disabled
['email', 'uri']	Only listed formats enabled
{ mode: 'fast' }	Full ajv-formats plugin config

Route Parameter Resolution

Route parameters are resolved from acc.route?.params (ergo-router) with a fallback to acc.params (standalone).

Return Value

The middleware returns undefined on success — validation is a gate, not a data producer.

Error Responses

Status	Condition
422 Unprocessable Entity	Validation failure — response includes details array with per-field errors
500 Internal Server Error	A body schema is configured but acc.body is missing — body() middleware was not placed before validate() in the pipeline. Emits a one-time ERGO_VALIDATE_NO_BODY process warning

Usage

Standalone

import { compose, body, url, validate } from "@centralping/ergo";

const pipeline = compose(
  {fn: body(), setPath: "body"},
  {fn: url(), setPath: "url"},
  validate({
    body: {
      type: "object",
      properties: { name: { type: "string" } },
      required: ["name"],
    },
    query: {
      type: "object",
      properties: {
        page: { type: "string", pattern: "^[0-9]+$" },
      },
    },
  }),
);

ergo-router

router.post("/users", {
  validate: {
    body: {
      type: "object",
      properties: { name: { type: "string", format: "email" } },
      required: ["name"],
    },
    params: {
      type: "object",
      properties: { id: { type: "string", minLength: 1 } },
      required: ["id"],
    },
  },
  execute: (req, res, acc) => ({
    response: { statusCode: 201, body: { created: true } },
  }),
});

API Reference

See the auto-generated validate API docs.