JSON Schema Validation¶

Validate payloads against JSON Schema documents. Check input before your business code and optionally validate its response.

Install¶

Use Go 1.27 or newer:

CGO_ENABLED=0 go get github.com/rambow-cloud/powertools-lambda-go/validation@v1.2.0
CGO_ENABLED=0 go get github.com/rambow-cloud/powertools-lambda-go/logger@v1.2.0

Validate an order¶

Require a nonempty string id. The schema and payload are ordinary Go values; this program runs locally.

Input

{
  "id": "ORD-123"
}

Code

package main

import (
    "context"
    "os"

    "github.com/rambow-cloud/powertools-lambda-go/logger"
    "github.com/rambow-cloud/powertools-lambda-go/validation"
)

func main() {
    appLog := logger.New(logger.WithServiceName("orders"))
    if err := run(appLog); err != nil {
        if logErr := appLog.Error("Application failed", err); logErr != nil {
            panic(logErr)
        }
        os.Exit(1)
    }
}

func run(appLog *logger.Logger) error {
    schema := map[string]any{
        "type":     "object",
        "required": []string{"id"},
        "properties": map[string]any{
            "id": map[string]any{"type": "string", "minLength": 1},
        },
    }
    payload := map[string]any{"id": "ORD-123"}
    if _, err := validation.Validate(context.Background(), payload, schema, validation.Options{}); err != nil {
        return err
    }
    return appLog.Info("Order valid", logger.Fields{"order": payload})
}

The Logger timestamp varies on each run.

Output

{
  "level": "INFO",
  "message": "Order valid",
  "timestamp": "2026-10-15T00:00:00.000Z",
  "service": "orders",
  "sampling_rate": 0,
  "order": {
    "id": "ORD-123"
  }
}

Reuse a compiled schema¶

Compile during initialization when the same schema handles many requests:

validator, err := validation.Compile(ctx, schema, validation.Options{})
if err != nil {
    return err
}
value, err := validator.Validate(ctx, payload)

With {"id":"ORD-123"}, validation returns the payload. A missing or empty id returns a SchemaValidationError.

Validate an embedded payload¶

validator, err := validation.Compile(ctx, schema,
    validation.Options{Envelope: "detail"})

Input

{
  "source": "orders",
  "detail": {
    "id": "ORD-123"
  }
}

Validated value

{
  "id": "ORD-123"
}

Choose a schema dialect¶

Dialect	Configuration
Draft 7	Default compiler
Draft 2019-09	`Options{Compiler: validation.Draft201909Compiler{}}`
Draft 2020-12	`Options{Compiler: validation.Draft202012Compiler{}}`

See compiler options for injection examples. Keywords, references and strict mode cover schema configuration.

Things to know¶

Validation does not add defaults, coerce types or delete extra properties by default.
Use WrapHandler to validate inbound/outbound values in a Lambda handler.
Use Parser when you want typed Go schema composition and event transformations.

Next steps¶

See the API and behavior notes for advanced options, and module installation for dependencies.