mappath

README

mappath

mappath is a simple package for searching and modifying generic maps (map[string]any) or slices ([]any) using keypaths.

This functionality was originally implemented in Neptunus to navigate through event data.

It also supports negative indexes for slices that already exists. In this case, target element will be len(slice) - |index|. For example, you can get last element from this slice - [0, 2, 4, 6] - by -1 index, because it's length is 4 and 4-1=3.

Examples

rawJson := `
{
    "message": "user login",
    "metadata": {
        "user": {
            "name": "John Doe",
            "email": "johndoe@gmail.com",
            "roles": [ "employee", "manager" ],
            "age": 42
        }
    }
}
`

var data any
if err := json.Unmarshal([]byte(rawJson), &data); err != nil {
    return err
}

// get first user role
role, _ := mappath.Get(data, "metadata.user.roles.0")

// add login to user metadata
data, _ = mappath.Put(data, "metadata.user.login", "johndoe12")

// delete user second role
data, _ = mappath.Delete(data, "metadata.user.roles.1")

It may be not so conveniently, when function returns nil data if error occured. For this cases you can use Container:

rawJson := `
{
    "message": "user login",
    "metadata": {
        "user": {
            "name": "John Doe",
            "email": "johndoe@gmail.com",
            "roles": [ "employee", "manager" ],
            "age": 42
        }
    }
}
`

c := &mappath.Container{}
if err := json.Unmarshal([]byte(rawJson), &c.Data); err != nil {
    return err
}

// get first user role
role, err := c.Get("metadata.user.roles.0")

// add login to user metadata
err = c.Put("metadata.user.login", "johndoe12")

// delete user second role
err = c.Delete("metadata.user.roles.1")

Container stores data and updates it only if change operations have been performed successfully.

Documentation

Index

• func Clone(p any) any
• func Delete(p any, key string) (any, error)
• func Get(p any, key string) (any, error)
• func Put(p any, key string, val any) (any, error)
• type Container
  • func (c *Container) Clone() *Container
  • func (c *Container) Delete(key string) error
  • func (c *Container) Get(key string) (any, error)
  • func (c *Container) Put(key string, val any) error
• type InvalidPathError
  • func (e *InvalidPathError) Error() string
• type NotFoundError
  • func (e *NotFoundError) Error() string

Functions

func Clone

func Clone(p any) any

Clone passed map[string]any or []any.

func Delete

func Delete(p any, key string) (any, error)

Delete a value on a specified path in the provided map[string]any or []any and get the updated object.

func Get

func Get(p any, key string) (any, error)

Get a value by specified key from provided map[string]any or []any.

func Put

func Put(p any, key string, val any) (any, error)

Put a passed value on a specified path in the provided map[string]any or []any and get the updated object.

Types

type Container

type Container struct {
	Data any
}

Container stores data and updates it only if change operations have been performed successfully.

func (*Container) Clone

func (c *Container) Clone() *Container

func (*Container) Delete

func (c *Container) Delete(key string) error

func (*Container) Get

func (c *Container) Get(key string) (any, error)

func (*Container) Put

func (c *Container) Put(key string, val any) error

type InvalidPathError

type InvalidPathError struct {
	Path   string
	Reason string
}

func (*InvalidPathError) Error

func (e *InvalidPathError) Error() string

type NotFoundError

type NotFoundError struct {
	Path   string
	Reason string
}

func (*NotFoundError) Error

func (e *NotFoundError) Error() string