pip-services4-components-node
Version:
Portable Component Model in Node.js / ES2017
249 lines • 9.06 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
exports.DependencyResolver = void 0;
/** @module refer */
const pip_services4_commons_node_1 = require("pip-services4-commons-node");
const ReferenceException_1 = require("./ReferenceException");
const Descriptor_1 = require("./Descriptor");
/**
* Helper class for resolving component dependencies.
*
* The resolver is configured to resolve named dependencies by specific locator.
* During deployment the dependency locator can be changed.
*
* This mechanism can be used to clarify specific dependency among several alternatives.
* Typically components are configured to retrieve the first dependency that matches
* logical group, type and version. But if container contains more than one instance
* and resolution has to be specific about those instances, they can be given a unique
* name and dependency resolvers can be reconfigured to retrieve dependencies by their name.
*
* ### Configuration parameters ###
*
* dependencies:
* - [dependency name 1]: Dependency 1 locator (descriptor)
* - ...
* - [dependency name N]: Dependency N locator (descriptor)
*
* ### References ###
*
* References must match configured dependencies.
*
* ### Example ###
*
* class MyComponent: IConfigurable, IReferenceable {
* private _dependencyResolver: DependencyResolver = new DependencyResolver();
* private _persistence: IMyPersistence;
* ...
*
* public constructor() {
* this._dependencyResolver.put("persistence", new Descriptor("mygroup", "persistence", "*", "*", "1.0"));
* }
*
* public configure(config: ConfigParams): void {
* this._dependencyResolver.configure(config);
* }
*
* public setReferences(references: IReferences): void {
* this._dependencyResolver.setReferences(references);
* this._persistence = this._dependencyResolver.getOneRequired<IMyPersistence>("persistence");
* }
* }
*
* // Create mycomponent and set specific dependency out of many
* let component = new MyComponent();
* component.configure(ConfigParams.fromTuples(
* "dependencies.persistence", "mygroup:persistence:*:persistence2:1.0"
* // Override default persistence dependency
* ));
* component.setReferences(References.fromTuples(
* new Descriptor("mygroup","persistence","*","persistence1","1.0"), new MyPersistence(),
* new Descriptor("mygroup","persistence","*","persistence2","1.0"), new MyPersistence()
* // This dependency shall be set
* ));
*
* @see [[IReferences]]
*/
class DependencyResolver {
/**
* Creates a new instance of the dependency resolver.
*
* @param config (optional) default configuration where key is dependency name and value is locator (descriptor)
* @param references (optional) default component references
*
* @see [[ConfigParams]]
* @see [[configure]]
* @see [[IReferences]]
* @see [[setReferences]]
*/
constructor(config, references) {
this._dependencies = {};
if (config != null) {
this.configure(config);
}
if (references != null) {
this.setReferences(references);
}
}
/**
* Configures the component with specified parameters.
*
* @param config configuration parameters to set.
*
* @see [[ConfigParams]]
*/
configure(config) {
const dependencies = config.getSection("dependencies");
const names = dependencies.getKeys();
for (let index = 0; index < names.length; index++) {
const name = names[index];
const locator = dependencies.get(name);
if (locator == null)
continue;
try {
const descriptor = Descriptor_1.Descriptor.fromString(locator);
if (descriptor != null) {
this._dependencies[name] = descriptor;
}
else {
this._dependencies[name] = locator;
}
}
catch (ex) {
this._dependencies[name] = locator;
}
}
}
/**
* Sets the component references. References must match configured dependencies.
*
* @param references references to set.
*/
setReferences(references) {
this._references = references;
}
/**
* Adds a new dependency into this resolver.
*
* @param name the dependency's name.
* @param locator the locator to find the dependency by.
*/
put(name, locator) {
this._dependencies[name] = locator;
}
/**
* Gets a dependency locator by its name.
*
* @param name the name of the dependency to locate.
* @returns the dependency locator or null if locator was not configured.
*/
locate(name) {
if (name == null) {
throw new Error("Dependency name cannot be null");
}
if (this._references == null) {
throw new Error("References shall be set");
}
return this._dependencies[name];
}
/**
* Gets all optional dependencies by their name.
*
* @param name the dependency name to locate.
* @returns a list with found dependencies or empty list of no dependencies was found.
*/
getOptional(name) {
const locator = this.locate(name);
return locator != null ? this._references.getOptional(locator) : null;
}
/**
* Gets all required dependencies by their name.
* At least one dependency must be present.
* If no dependencies was found it throws a [[ReferenceException]]
*
* @param name the dependency name to locate.
* @returns a list with found dependencies.
*
* @throws a [[ReferenceException]] if no dependencies were found.
*/
getRequired(name) {
const locator = this.locate(name);
if (locator == null) {
throw new ReferenceException_1.ReferenceException(null, name);
}
return this._references.getRequired(locator);
}
/**
* Gets one optional dependency by its name.
*
* @param name the dependency name to locate.
* @returns a dependency reference or null of the dependency was not found
*/
getOneOptional(name) {
const locator = this.locate(name);
return locator != null ? this._references.getOneOptional(locator) : null;
}
/**
* Gets one required dependency by its name.
* At least one dependency must present.
* If the dependency was found it throws a [[ReferenceException]]
*
* @param name the dependency name to locate.
* @returns a dependency reference
*
* @throws a [[ReferenceException]] if dependency was not found.
*/
getOneRequired(name) {
const locator = this.locate(name);
if (locator == null) {
throw new ReferenceException_1.ReferenceException(null, name);
}
return this._references.getOneRequired(locator);
}
/**
* Finds all matching dependencies by their name.
*
* @param name the dependency name to locate.
* @param required true to raise an exception when no dependencies are found.
* @returns a list of found dependencies
*
* @throws a [[ReferenceException]] of required is true and no dependencies found.
*/
find(name, required) {
if (name == null) {
throw new Error("Name cannot be null");
}
const locator = this.locate(name);
if (locator == null) {
if (required) {
throw new ReferenceException_1.ReferenceException(null, name);
}
return null;
}
return this._references.find(locator, required);
}
/**
* Creates a new DependencyResolver from a list of key-value pairs called tuples
* where key is dependency name and value the depedency locator (descriptor).
*
* @param tuples a list of values where odd elements are dependency name and the following even elements are dependency locator (descriptor)
* @returns a newly created DependencyResolver.
*
* @see [[fromTuplesArray]]
*/
static fromTuples(...tuples) {
const result = new DependencyResolver();
if (tuples == null || tuples.length == 0) {
return result;
}
for (let index = 0; index < tuples.length; index += 2) {
if (index + 1 >= tuples.length)
break;
const name = pip_services4_commons_node_1.StringConverter.toString(tuples[index]);
const locator = tuples[index + 1];
result.put(name, locator);
}
return result;
}
}
exports.DependencyResolver = DependencyResolver;
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