JMESPath¶

Select and transform values in JSON documents, including JSON/Base64 data inside Lambda event envelopes.

Install¶

Use Go 1.27 or newer:

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

Select paid order IDs¶

This local program searches the orders array and logs only IDs whose status is PAID.

Input

{
  "orders": [
    {
      "id": "ORD-123",
      "status": "PAID"
    },
    {
      "id": "ORD-456",
      "status": "PENDING"
    }
  ]
}

Code

package main

import (
    "os"

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

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 {
    data := map[string]any{"orders": []any{
        map[string]any{"id": "ORD-123", "status": "PAID"},
        map[string]any{"id": "ORD-456", "status": "PENDING"},
    }}
    value, err := jmespath.Search("orders[?status == 'PAID'].id", data)
    if err != nil {
        return err
    }
    return appLog.Info("Paid orders selected", logger.Fields{"order_ids": value})
}

The Logger timestamp varies on each run.

Output

{
  "level": "INFO",
  "message": "Paid orders selected",
  "timestamp": "2026-10-15T00:00:00.000Z",
  "service": "orders",
  "sampling_rate": 0,
  "order_ids": [
    "ORD-123"
  ]
}

Reuse an expression¶

query, err := jmespath.Compile("orders[?status == 'PAID'].id")
if err != nil {
    return err
}
value, err := query.Search(data)

value is a Go array value, not a JSON string. Marshal it when your caller needs JSON.

Decode an SQS body¶

value, err := jmespath.ExtractDataFromEnvelope(event, jmespath.SQS)

Input

{
  "Records": [
    {
      "body": "{\"id\":\"ORD-123\"}"
    }
  ]
}

Result

[
  {
    "id": "ORD-123"
  }
]

ExtractDataFromEnvelope enables Powertools decoding functions automatically. For custom expressions, pass WithPowertoolsFunctions() to enable powertools_json, powertools_base64 and powertools_base64_gzip.

Things to know¶

Compile reusable expressions once.
Logger can use this optional module to extract correlation IDs; installing Logger alone does not install JMESPath.
Bound compressed/untrusted payload sizes before decoding.

Next steps¶

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