contextx

README

contextx

Context value helper library.
Differences between context package this holds value in a map with mutex lock. Values readable from parent context.

go get github.com/rakunlabs/contextx

Usage

// set value first initialize context value map if not exist
ctx := contextx.WithValue(context.Background(), "secret", "xxx")

// map like access
if v, ok := contextx.Value[string](ctx, "secret"); ok {
    // v is string
}

Use WithKey option to set multiple data holder on same context.

Documentation

Overview

Example

package main

import (
	"context"
	"fmt"

	"github.com/rakunlabs/contextx"
)

func main() {
	ctx := contextx.WithValue(context.Background(), "secret", "xxx")

	if v, ok := contextx.Value[string](ctx, "secret"); ok {
		fmt.Println("[" + v + "]")
	}

	ctx = contextx.WithValue(ctx, "another", "yyy", contextx.WithKey("customKey"))

	if v, ok := contextx.Value[string](ctx, "another"); ok {
		fmt.Println("[" + v + "]")
	} else {
		// expected not found
		fmt.Println("not found")
	}

	if v, ok := contextx.Value[string](ctx, "secret", contextx.WithKey("customKey")); ok {
		fmt.Println("[" + v + "]")
	} else {
		// expected not found
		fmt.Println("not found")
	}

	if v, ok := contextx.Value[string](ctx, "another", contextx.WithKey("customKey")); ok {
		// expected found
		fmt.Println("[" + v + "]")
	}

}

Output:

[xxx]
not found
not found
[yyy]

Index

• func Init(ctx context.Context, opts ...Option) context.Context
• func Value[T any](ctx context.Context, key any, opts ...Option) (T, bool)
• func WithValue(ctx context.Context, key, value any, opts ...Option) context.Context
• type CtxKey
• type Data
  • func Internal(ctx context.Context, opts ...Option) (*Data, bool)
• type Option
  • func WithKey(key any) Option

Examples

• Package

Functions

func Init

func Init(ctx context.Context, opts ...Option) context.Context

Init context with internal value.

If context is nil, it use context.Background().

func Value

func Value[T any](ctx context.Context, key any, opts ...Option) (T, bool)

Value gets value from context's map.

Returns same as map's value and ok.

func WithValue

func WithValue(ctx context.Context, key, value any, opts ...Option) context.Context

WithValue sets value to context's map.

If context is nil, it use context.Background(). If context's map is nil, it will init context's map and add value to ctx.

Types

type CtxKey

type CtxKey string

const CtxInternal CtxKey = "internal"

type Data

type Data struct {
	V map[any]interface{}

	M sync.RWMutex
}

func Internal

func Internal(ctx context.Context, opts ...Option) (*Data, bool)

Internal gets internal data value from context.

If context is nil return nil and false.

type Option

type Option func(*option)

func WithKey

func WithKey(key any) Option

WithKey sets the key for the option.