transform

README

transform

Contains interfaces and methods for transforming data.

Documentation

Overview

Package transform provides functions for transforming messages.

Index

• func Apply(ctx context.Context, tf []Transformer, msgs ...*message.Message) ([]*message.Message, error)
• type Factory
• type Transformer
  • func New(ctx context.Context, cfg config.Config) (Transformer, error)

Examples

• Transformer

Functions

func Apply

func Apply(ctx context.Context, tf []Transformer, msgs ...*message.Message) ([]*message.Message, error)

Applies one or more transform functions to one or more messages.

Types

type Factory

type Factory func(context.Context, config.Config) (Transformer, error)

Factory can be used to implement custom transform factory functions.

type Transformer

type Transformer interface {
	Transform(context.Context, *message.Message) ([]*message.Message, error)
}

Transformer is the interface implemented by all transforms and provides the ability to transform a message.

Example

package main

import (
	"context"
	"fmt"

	"github.com/brexhq/substation/v2/config"
	"github.com/brexhq/substation/v2/message"
	"github.com/brexhq/substation/v2/transform"
)

func main() {
	ctx := context.TODO()

	// Copies the value of key "a" into key "b".
	cfg := config.Config{
		Type: "object_copy",
		Settings: map[string]interface{}{
			"object": map[string]interface{}{
				"source_key": "a",
				"target_key": "b",
			},
		},
	}

	tf, err := transform.New(ctx, cfg)
	if err != nil {
		// handle err
		panic(err)
	}

	// Transformer is applied to a message.
	msg := message.New().SetData([]byte(`{"a":1}`))
	results, err := tf.Transform(ctx, msg)
	if err != nil {
		// handle err
		panic(err)
	}

	for _, c := range results {
		fmt.Println(string(c.Data()))
	}

}

Output:

{"a":1,"b":1}

func New

func New(ctx context.Context, cfg config.Config) (Transformer, error)

New is a factory function for returning a configured Transformer.