Class: I18nMiddleware

The entrypoint middleware choosing the language of each request. Add it to the middlewares of buildEntrypoints(). For each request, it reads the languages the request asks for (I18nMiddleware.requested), negotiates them with the supported languages of the I18n component (I18n.negotiate, the default language when none matches), and makes the result:

• the request's context.locale;
• the language of the Translator the request's objects inject;
• the language of the validation errors of the request (its input, @Accept/@Return, the DTO.validate calls of its code);
• the language of the exceptions it throws: a lakutata Exception whose errno has a message errors.<errno> (errors.E_ORDER_NOT_FOUND) gets that message, formatted with the exception's template parameters.

The languages are read, preferred first: for HTTP, the lang query parameter, the lang cookie, then Accept-Language; for Socket.IO, the same from the connection's handshake; for the HTTP service adapter and the JSON-RPC adapter over HTTP or WebSocket, the same from the HTTP request (for WebSocket, the request opening the connection); for the command line and the other service transports, the process's environment (environmentLocales) then the process's language; for the schedules, none. It uses the component registered as i18n; a subclass changes the component, the names of the query parameter and of the cookie, or the languages read (requested()).

Example

import {type BaseContext} from 'lakutata/com/entrypoint'
import {Inject} from 'lakutata/decorator/di'
import {I18nMiddleware, type I18n} from 'lakutata/com/i18n'

//BuildEntrypoints({middlewares: [LanguageMiddleware], ...}) in place of I18nMiddleware
export class LanguageMiddleware extends I18nMiddleware {
    //The component registered as "lang"
    @Inject('lang')
    protected readonly i18n: I18n

    //?locale=zh-CN
    protected readonly queryParameter: string = 'locale'

    protected readonly environmentVariable: string = 'SHOP_LANG'

    //The language saved by the signed-in user first
    protected requested(context: BaseContext): string[] {
        const saved: unknown = context.data.userLanguage
        return [...(typeof saved === 'string' ? [saved] : []), ...super.requested(context)]
    }
}

Extends

• Middleware

Constructors

Constructor

new I18nMiddleware(cradleProxy): I18nMiddleware

Called by the container only: an object is created through a container (see the class description), never with new.

Parameters

cradleProxy

Record<string | symbol, any>

The container's resolution proxy.

Returns

I18nMiddleware

Inherited from

Middleware.constructor

Properties

constructor

constructor: Function

The initial value of Object.prototype.constructor is the standard built-in Object constructor.

Inherited from

Middleware.constructor

Accessors

$id

Get Signature

get $id(): string | symbol

The name the object was registered under (its key in the module options), or a symbol of its class for an object registered by its class or built without registration.

Returns

string | symbol

Inherited from

Middleware.$id

---

$symbol

Get Signature

get $symbol(): symbol

A symbol unique to the instance (made from its $uuid), created on first read.

Returns

symbol

Inherited from

Middleware.$symbol

---

$uuid

Get Signature

get $uuid(): string

A random UUID identifying the instance.

Returns

string

Inherited from

Middleware.$uuid

---

className

Get Signature

get static className(): string

The name of the class.

Returns

string

Inherited from

Middleware.className

---

className

Get Signature

get className(): string

The name of the object's class.

Returns

string

Inherited from

Middleware.className

Methods

[asyncDispose]()

[asyncDispose](): Promise<void>

Dispose the object at the end of an await using block, as BaseObject.dispose.

Returns

Promise<void>

Resolves once the object is destroyed.

Inherited from

Middleware.[asyncDispose]

---

acceptsOption()

static acceptsOption(name, value): boolean

Whether the class accepts an option which is not one of its @Configurable properties (an option it reads with getConfigurableRecords()): the modules check the options of the objects they declare and warn of the options the classes do not accept. Override it in the classes reading options without configurable properties.

Parameters

name

string

The option name.

value

unknown

The option value.

Returns

boolean

true when the option is accepted; false by default.

Inherited from

Middleware.acceptsOption

---

assign()

Call Signature

static assign<T, U>(target, source): T & U

Copy the values of all of the enumerable own properties from one or more source objects to a target object. Returns the target object.

Type Parameters

T

T extends object

U

U

Parameters

target

T

The target object to copy to.

source

U

The source object from which to copy properties.

Returns

T & U

Inherited from

Middleware.assign

Call Signature

static assign<T, U, V>(target, source1, source2): T & U & V

Copy the values of all of the enumerable own properties from one or more source objects to a target object. Returns the target object.

Type Parameters

T

T extends object

U

U

V

V

Parameters

target

T

The target object to copy to.

source1

U

The first source object from which to copy properties.

source2

V

The second source object from which to copy properties.

Returns

T & U & V

Inherited from

Middleware.assign

Call Signature

static assign<T, U, V, W>(target, source1, source2, source3): T & U & V & W

Copy the values of all of the enumerable own properties from one or more source objects to a target object. Returns the target object.

Type Parameters

T

T extends object

U

U

V

V

W

W

Parameters

target

T

The target object to copy to.

source1

U

The first source object from which to copy properties.

source2

V

The second source object from which to copy properties.

source3

W

The third source object from which to copy properties.

Returns

T & U & V & W

Inherited from

Middleware.assign

Call Signature

static assign(target, ...sources): any

Copy the values of all of the enumerable own properties from one or more source objects to a target object. Returns the target object.

Parameters

target

object

The target object to copy to.

sources

...any[]

One or more source objects from which to copy properties

Returns

any

Inherited from

Middleware.assign

---

create()

Call Signature

static create(o): any

Creates an object that has the specified prototype or that has null prototype.

Parameters

o

object | null

Object to use as a prototype. May be null.

Returns

any

Inherited from

Middleware.create

Call Signature

static create(o, properties): any

Creates an object that has the specified prototype, and that optionally contains specified properties.

Parameters

o

object | null

Object to use as a prototype. May be null

properties

PropertyDescriptorMap & ThisType<any>

JavaScript object that contains one or more property descriptors.

Returns

any

Inherited from

Middleware.create

---

defineProperties()

static defineProperties<T>(o, properties): T

Adds one or more properties to an object, and/or modifies attributes of existing properties.

Type Parameters

T

T

Parameters

o

T

Object on which to add or modify the properties. This can be a native JavaScript object or a DOM object.

properties

PropertyDescriptorMap & ThisType<any>

JavaScript object that contains one or more descriptor objects. Each descriptor object describes a data property or an accessor property.

Returns

T

Inherited from

Middleware.defineProperties

---

defineProperty()

static defineProperty<T>(o, p, attributes): T

Adds a property to an object, or modifies attributes of an existing property.

Type Parameters

T

T

Parameters

o

T

Object on which to add or modify the property. This can be a native JavaScript object (that is, a user-defined object or a built in object) or a DOM object.

p

PropertyKey

The property name.

attributes

PropertyDescriptor & ThisType<any>

Descriptor for the property. It can be for a data property or an accessor property.

Returns

T

Inherited from

Middleware.defineProperty

---

dispose()

dispose(): Promise<void>

Destroy the object: its beforeDestroy(), the objects it created, then its destroy(). Calling it more than once destroys once. A disposed singleton or scoped object is dropped from its container, which creates a new one on the next request. Using a destroyed object (getObject(), buildObject()) throws an ObjectDestroyedException.

Returns

Promise<void>

Resolves once the object is destroyed.

Throws

The error of the object's own beforeDestroy() or destroy() (an AggregateError when several fail); the errors of the objects it created are reported through the application's logger instead.

Inherited from

Middleware.dispose

---

entries()

Call Signature

static entries<T>(o): [string, T][]

Returns an array of key/values of the enumerable own properties of an object

Type Parameters

T

T

Parameters

o

{[s: string]: T; } | ArrayLike<T>

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

[string, T][]

Inherited from

Middleware.entries

Call Signature

static entries(o): [string, any][]

Returns an array of key/values of the enumerable own properties of an object

Parameters

o

{ }

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

[string, any][]

Inherited from

Middleware.entries

---

freeze()

Call Signature

static freeze<T>(f): T

Prevents the modification of existing property attributes and values, and prevents the addition of new properties.

Type Parameters

T

T extends Function

Parameters

f

T

Object on which to lock the attributes.

Returns

T

Inherited from

Middleware.freeze

Call Signature

static freeze<T, U>(o): Readonly<T>

Prevents the modification of existing property attributes and values, and prevents the addition of new properties.

Type Parameters

T

T extends object

U

U extends string | number | bigint | boolean | symbol

Parameters

o

T

Object on which to lock the attributes.

Returns

Readonly<T>

Inherited from

Middleware.freeze

Call Signature

static freeze<T>(o): Readonly<T>

Prevents the modification of existing property attributes and values, and prevents the addition of new properties.

Type Parameters

T

T

Parameters

o

T

Object on which to lock the attributes.

Returns

Readonly<T>

Inherited from

Middleware.freeze

---

fromEntries()

Call Signature

static fromEntries<T>(entries): object

Returns an object created by key-value entries for properties and methods

Type Parameters

T

T = any

Parameters

entries

Iterable<readonly [PropertyKey, T]>

An iterable object that contains key-value entries for properties and methods.

Returns

object

Inherited from

Middleware.fromEntries

Call Signature

static fromEntries(entries): any

Returns an object created by key-value entries for properties and methods

Parameters

entries

Iterable<readonly any[]>

An iterable object that contains key-value entries for properties and methods.

Returns

any

Inherited from

Middleware.fromEntries

---

getMethod()

getMethod(name, throwExceptionIfNotFound?): (...args) => any

Get a method bound to the object, to call it by name.

Parameters

name

string | symbol

The method name or symbol.

throwExceptionIfNotFound?

boolean

Throw when the method does not exist, instead of returning a function doing nothing; false by default.

Returns

The bound method, or a function doing nothing (returning undefined) when it does not exist.

(...args) => any

Throws

When the method does not exist and throwExceptionIfNotFound is true.

Inherited from

Middleware.getMethod

---

getOwnPropertyDescriptor()

static getOwnPropertyDescriptor(o, p): PropertyDescriptor | undefined

Gets the own property descriptor of the specified object. An own property descriptor is one that is defined directly on the object and is not inherited from the object's prototype.

Parameters

o

any

Object that contains the property.

p

PropertyKey

Name of the property.

Returns

PropertyDescriptor | undefined

Inherited from

Middleware.getOwnPropertyDescriptor

---

getOwnPropertyDescriptors()

static getOwnPropertyDescriptors<T>(o): { [P in string | number | symbol]: TypedPropertyDescriptor<T[P]> } & object

Returns an object containing all own property descriptors of an object

Type Parameters

T

T

Parameters

o

T

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

{ [P in string | number | symbol]: TypedPropertyDescriptor<T[P]> } & object

Inherited from

Middleware.getOwnPropertyDescriptors

---

getOwnPropertyNames()

static getOwnPropertyNames(o): string[]

Returns the names of the own properties of an object. The own properties of an object are those that are defined directly on that object, and are not inherited from the object's prototype. The properties of an object include both fields (objects) and functions.

Parameters

o

any

Object that contains the own properties.

Returns

string[]

Inherited from

Middleware.getOwnPropertyNames

---

getOwnPropertySymbols()

static getOwnPropertySymbols(o): symbol[]

Returns an array of all symbol properties found directly on object o.

Parameters

o

any

Object to retrieve the symbols from.

Returns

symbol[]

Inherited from

Middleware.getOwnPropertySymbols

---

getProperty()

getProperty<T>(propertyKey, defaultValue?): T

Read an own property of the object.

Type Parameters

T

T = any

Parameters

propertyKey

string

The property name.

defaultValue?

T

The value returned when the object has no own property of this name.

Returns

T

The property value, or the default value.

Inherited from

Middleware.getProperty

---

getPrototypeOf()

static getPrototypeOf(o): any

Returns the prototype of an object.

Parameters

o

any

The object that references the prototype.

Returns

any

Inherited from

Middleware.getPrototypeOf

---

handle()

handle(invocation, next): Promise<unknown>

Negotiate the request's language, set context.locale, create the request's Translator, then run the next middlewares and the action with the validations in that language, translating the exception they throw.

Parameters

invocation

ActionInvocation

The action invocation: its context and its container.

next

Next

Runs the rest of the chain.

Returns

Promise<unknown>

The result of the rest of the chain; an exception it throws is rethrown, its message translated by I18nMiddleware.translate.

Overrides

Middleware.handle

---

hasMethod()

hasMethod(name): boolean

Whether the object has a method of this name or symbol (a function of its class, not an own property).

Parameters

name

string | symbol

The method name or symbol.

Returns

boolean

true when the method exists.

Inherited from

Middleware.hasMethod

---

hasOwn()

static hasOwn(o, v): boolean

Determines whether an object has a property with the specified name.

Parameters

o

object

An object.

v

PropertyKey

A property name.

Returns

boolean

Inherited from

Middleware.hasOwn

---

hasOwnProperty()

hasOwnProperty(v): boolean

Determines whether an object has a property with the specified name.

Parameters

v

PropertyKey

A property name.

Returns

boolean

Inherited from

Middleware.hasOwnProperty

---

hasProperty()

hasProperty(propertyKey): boolean

Whether the object has an own property (not a method or accessor of its class) of this name or symbol.

Parameters

propertyKey

string | symbol

The property name or symbol.

Returns

boolean

true when the property exists.

Inherited from

Middleware.hasProperty

---

is()

static is(value1, value2): boolean

Returns true if the values are the same value, false otherwise.

Parameters

value1

any

The first value.

value2

any

The second value.

Returns

boolean

Inherited from

Middleware.is

---

isExtensible()

static isExtensible(o): boolean

Returns a value that indicates whether new properties can be added to an object.

Parameters

o

any

Object to test.

Returns

boolean

Inherited from

Middleware.isExtensible

---

isFrozen()

static isFrozen(o): boolean

Returns true if existing property attributes and values cannot be modified in an object, and new properties cannot be added to the object.

Parameters

o

any

Object to test.

Returns

boolean

Inherited from

Middleware.isFrozen

---

isPrototypeOf()

isPrototypeOf(v): boolean

Determines whether an object exists in another object's prototype chain.

Parameters

v

Object

Another object whose prototype chain is to be checked.

Returns

boolean

Inherited from

Middleware.isPrototypeOf

---

isSealed()

static isSealed(o): boolean

Returns true if existing property attributes cannot be modified in an object and new properties cannot be added to the object.

Parameters

o

any

Object to test.

Returns

boolean

Inherited from

Middleware.isSealed

---

keys()

Call Signature

static keys(o): string[]

Returns the names of the enumerable string properties and methods of an object.

Parameters

o

object

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

string[]

Inherited from

Middleware.keys

Call Signature

static keys(o): string[]

Returns the names of the enumerable string properties and methods of an object.

Parameters

o

{ }

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

string[]

Inherited from

Middleware.keys

---

preventExtensions()

static preventExtensions<T>(o): T

Prevents the addition of new properties to an object.

Type Parameters

T

T

Parameters

o

T

Object to make non-extensible.

Returns

T

Inherited from

Middleware.preventExtensions

---

propertyIsEnumerable()

propertyIsEnumerable(v): boolean

Determines whether a specified property is enumerable.

Parameters

v

PropertyKey

A property name.

Returns

boolean

Inherited from

Middleware.propertyIsEnumerable

---

propertyNames()

propertyNames(): string[]

The names of the object's own properties (not its class's methods and accessors).

Returns

string[]

The names.

Inherited from

Middleware.propertyNames

---

propertySymbols()

propertySymbols(): symbol[]

The symbols of the object's own properties.

Returns

symbol[]

The symbols.

Inherited from

Middleware.propertySymbols

---

seal()

static seal<T>(o): T

Prevents the modification of attributes of existing properties, and prevents the addition of new properties.

Type Parameters

T

T

Parameters

o

T

Object on which to lock the attributes.

Returns

T

Inherited from

Middleware.seal

---

setProperty()

setProperty(propertyKey, value): void

Set a property of the object; the value is not validated, even for a @Configurable property.

Parameters

propertyKey

string

The property name.

value

any

The value.

Returns

void

Inherited from

Middleware.setProperty

---

setPrototypeOf()

static setPrototypeOf(o, proto): any

Sets the prototype of a specified object o to object proto or null. Returns the object o.

Parameters

o

any

The object to change its prototype.

proto

object | null

The value of the new prototype or null.

Returns

any

Inherited from

Middleware.setPrototypeOf

---

toLocaleString()

toLocaleString(): string

Returns a date converted to a string using the current locale.

Returns

string

Inherited from

Middleware.toLocaleString

---

toString()

toString(): string

Returns a string representation of an object.

Returns

string

Inherited from

Middleware.toString

---

valueOf()

valueOf(): Object

Returns the primitive value of the specified object.

Returns

Object

Inherited from

Middleware.valueOf

---

values()

Call Signature

static values<T>(o): T[]

Returns an array of values of the enumerable own properties of an object

Type Parameters

T

T

Parameters

o

{[s: string]: T; } | ArrayLike<T>

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

T[]

Inherited from

Middleware.values

Call Signature

static values(o): any[]

Returns an array of values of the enumerable own properties of an object

Parameters

o

{ }

Object that contains the properties and methods. This can be an object that you created or an existing Document Object Model (DOM) object.

Returns

any[]

Inherited from

Middleware.values