上下文绑定 & @targetName

原文链接

@targetName装饰器用于从上下文约束情况下访问构造函数参数的名称，即便代码被压缩也依旧可用。constructor(katana, shuriken) { ...在压缩后会变成constructor(a, b) { ...不过多亏了@targetName我们仍然可以在运行时引用之前的名称katana和shuriken。

interface Weapon {}

@injectable()
class Katana implements Weapon {}

@injectable()
class Shuriken implements Weapon {}

interface Ninja {
    katana: Weapon;
    shuriken: Weapon;
}

@injectable()
class Ninja implements Ninja {
    public katana: Weapon;
    public shuriken: Weapon;
    public constructor(
        @inject("Weapon") @targetName("katana") katana: Weapon,
        @inject("Weapon") @targetName("shuriken") shuriken: Weapon
    ) {
        this.katana = katana;
        this.shuriken = shuriken;
    }
}

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我们将Katana和Shuriken绑定到Weapon，同时通过when来添加自定义的约束条件以避免AMBIGUOUS_MATCH错误：

container.bind<Ninja>(ninjaId).to(Ninja);

container.bind<Weapon>("Weapon").to(Katana).when((request: interfaces.Request) => {
    return request.target.name.equals("katana");
});

container.bind<Weapon>("Weapon").to(Shuriken).when((request: interfaces.Request) => {
    return request.target.name.equals("shuriken");
});

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target字段部署IQueryableString接口以帮助您创建你的自定义约束条件：

interface QueryableString {
	 startsWith(searchString: string): boolean;
	 endsWith(searchString: string): boolean;
	 contains(searchString: string): boolean;
	 equals(compareString: string): boolean;
	 value(): string;
}

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我们提供了一些辅助方法来帮助您创建自定义约束：

import { Container, traverseAncerstors, taggedConstraint, namedConstraint, typeConstraint } from "inversify";

let whenParentNamedCanThrowConstraint = (request: interfaces.Request) => {
    return namedConstraint("canThrow")(request.parentRequest);
};

let whenAnyAncestorIsConstraint = (request: interfaces.Request) => {
    return traverseAncerstors(request, typeConstraint(Ninja));
};

let whenAnyAncestorTaggedConstraint = (request: interfaces.Request) => {
    return traverseAncerstors(request, taggedConstraint("canThrow")(true));
};

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InversifyJS自带的绑定语法包括了一些已经实现的常见的上下文约束：

interface BindingWhenSyntax<T> {
    when(constraint: (request: interfaces.Request) => boolean): interfaces.BindingOnSyntax<T>;
    whenTargetNamed(name: string): interfaces.BindingOnSyntax<T>;
    whenTargetTagged(tag: string, value: any): interfaces.BindingOnSyntax<T>;
    whenInjectedInto(parent: (Function|string)): interfaces.BindingOnSyntax<T>;
    whenParentNamed(name: string): interfaces.BindingOnSyntax<T>;
    whenParentTagged(tag: string, value: any): interfaces.BindingOnSyntax<T>;
    whenAnyAncestorIs(ancestor: (Function|string)): interfaces.BindingOnSyntax<T>;
    whenNoAncestorIs(ancestor: (Function|string)): interfaces.BindingOnSyntax<T>;
    whenAnyAncestorNamed(name: string): interfaces.BindingOnSyntax<T>;
    whenAnyAncestorTagged(tag: string, value: any): interfaces.BindingOnSyntax<T>;
    whenNoAncestorNamed(name: string): interfaces.BindingOnSyntax<T>;
    whenNoAncestorTagged(tag: string, value: any): interfaces.BindingOnSyntax<T>;
    whenAnyAncestorMatches(constraint: (request: interfaces.Request) => boolean): interfaces.BindingOnSyntax<T>;
    whenNoAncestorMatches(constraint: (request: interfaces.Request) => boolean): interfaces.BindingOnSyntax<T>;
}

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# 上下文绑定 & @targetName

上下文绑定 & @targetName