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Home > @loopback/context > Binding
Binding class
Binding represents an entry in the Context. Each binding has a key and a corresponding value getter.
Signature:
export declare class Binding<T = BoundValue> extends EventEmitter
Extends: EventEmitter
Constructors
| Constructor | Modifiers | Description |
|---|---|---|
| (constructor)(key, isLocked) | Constructs a new instance of the Binding class |
Properties
| Property | Modifiers | Type | Description |
|---|---|---|---|
| isLocked | boolean | ||
| key | readonly |
string | Key of the binding |
| providerConstructor | readonly |
Constructor<Provider<T>> | undefined | For bindings bound via toProvider(), this property contains the constructor function of the provider class |
| scope | readonly |
BindingScope | Scope of the binding to control how the value is cached/shared |
| source | readonly |
BindingSource<T> | undefined | |
| tagMap | readonly |
TagMap | Map for tag name/value pairs |
| tagNames | readonly |
string[] | Get an array of tag names |
| type | readonly |
BindingType | undefined | Type of the binding value getter |
| valueConstructor | readonly |
Constructor<T> | undefined | For bindings bound via toClass(), this property contains the constructor function of the class |
Methods
| Method | Modifiers | Description |
|---|---|---|
| apply(templateFns) | Apply one or more template functions to set up the binding with scope, tags, and other attributes as a group. | |
| applyDefaultScope(scope) | Apply default scope to the binding. It only changes the scope if it’s not set yet | |
| bind(key) | static |
A static method to create a binding so that we can do Binding.bind('foo').to('bar'); as new Binding('foo').to('bar') is not easy to read. |
| configure(key) | static |
Create a configuration binding for the given key |
| getValue(ctx, session) | <p>This is an internal function optimized for performance. Users should use @inject(key) or ctx.get(key) instead.</p><p>Get the value bound to this key. Depending on isSync, this function returns either: - the bound value - a promise of the bound value</p><p>Consumers wishing to consume sync values directly should use isPromiseLike to check the type of the returned value to decide how to handle it.</p> |
|
| getValue(ctx, options) | Returns a value or promise for this binding in the given context. The resolved value can be undefined if optional is set to true in options. |
|
| inScope(scope) | Set the binding scope | |
| inspect(options) | Inspect the binding to return a json representation of the binding information | |
| lock() | Lock the binding so that it cannot be rebound | |
| on(eventName, listener) | The “changed” event is emitted by methods such as tag, inScope, to, and toClass. |
|
| on(event, listener) | ||
| once(eventName, listener) | The “changed” event is emitted by methods such as tag, inScope, to, and toClass. |
|
| once(event, listener) | ||
| refresh(ctx) | Invalidate the binding cache so that its value will be reloaded next time. This is useful to force reloading a cached value when its configuration or dependencies are changed. **WARNING**: The state held in the cached value will be gone. | |
| tag(tags) | Tag the binding with names or name/value objects. A tag has a name and an optional value. If not supplied, the tag name is used as the value. | |
| to(value) | Bind the key to a constant value. The value must be already available at binding time, it is not allowed to pass a Promise instance. | |
| toAlias(keyWithPath) | Bind the key to an alias of another binding | |
| toClass(ctor) | Bind the key to an instance of the given class. | |
| toDynamicValue(factory) | Bind the key to a computed (dynamic) value. | |
| toInjectable(ctor) | <p>Bind to a class optionally decorated with @injectable. Based on the introspection of the class, it calls toClass/toProvider/toDynamicValue internally. The current binding key will be preserved (not being overridden by the key inferred from the class or options).</p><p>This is similar to createBindingFromClass() but applies to an existing binding.</p> |
|
| toJSON() | Convert to a plain JSON object | |
| toProvider(providerClass) | <p>Bind the key to a value computed by a Provider.</p><p>*</p> | |
| unlock() | Unlock the binding |