How to use aurelia-metadata - 10 common examples

class VValueConverter {}
    let vMeta = resources.autoRegister(container, VValueConverter);
    resourceMetaType = metadata.get(metadata.resource, VValueConverter);
    
    expect(vMeta).toBe(resourceMetaType);

    @valueConverter('v')
    class V {}
    expect(() => resources.autoRegister(container, V)).toThrow();

    // =========
    
    class BBindingBehavior {}
    let bMeta = resources.autoRegister(container, BBindingBehavior);
    resourceMetaType = metadata.get(metadata.resource, BBindingBehavior);

    expect(bMeta).toBe(resourceMetaType);

    @bindingBehavior('b')
    class B {}

    expect(() => resources.autoRegister(container, B)).toThrow();

    // ========

    class HViewEngineHooks {
      beforeCompile() {}
    }
    let hMeta = resources.autoRegister(container, HViewEngineHooks);
    resourceMetaType = metadata.get(metadata.resource, HViewEngineHooks);

context.viewModel = childContainer.viewModel = childContainer.get(viewModelResource.value);
        context.viewModelResource = viewModelResource;
        return context;
      });
    }
    // When viewModel in context is not a module path
    // only prepare the metadata and ensure the view model instance is ready
    // if viewModel is a class, instantiate it
    let ctor = context.viewModel.constructor;
    let isClass = typeof context.viewModel === 'function';
    if (isClass) {
      ctor = context.viewModel;
      childContainer.autoRegister(ctor);
    }
    let m = metadata.getOrCreateOwn(metadata.resource, HtmlBehaviorResource, ctor);
    // We don't call ViewResources.prototype.convention here as it should be called later
    // Just need to prepare the metadata for later usage
    m.elementName = m.elementName || 'dynamic-element';
    // HtmlBehaviorResource has its own guard to prevent unnecessary subsequent initialization calls
    // so it's safe to call initialize this way
    m.initialize(isClass ? childContainer : (context.container || childContainer), ctor);
    // simulate the metadata of view model, like it was analyzed by module analyzer
    // Cannot create a ResourceDescription instance here as it does too much
    context.viewModelResource = { metadata: m, value: ctor };
    // register the host element in case custom element view model declares it
    if (context.host) {
      childContainer.registerInstance(DOM.Element, context.host);
    }
    childContainer.viewModel = context.viewModel = isClass ? childContainer.get(ctor) : context.viewModel;
    return Promise.resolve(context);
  }

_validate(object, propertyName = null, rules = null) {
    const errors = [];
    if (!rules) {
      rules = metadata.get(metadataKey, object);
    }
    if (!rules) {
      // no rules defined for propertyName.
      return errors;
    }
    rules = rules.rules;
    for (let i = 0, ii = rules.length; i < ii; i++) {
      const ruleInfo = rules[i];
      if (propertyName !== null && ruleInfo.key !== propertyName) {
        continue;
      }
      const { name, config } = ruleInfo.rule;
      const validator = { [propertyName]: { [name]: config } };
      const result = validate(object, validator);
      if (result) {
        errors.push(new ValidationError(ruleInfo.rule, result[propertyName][0], object, propertyName));

_validate(object, propertyName = null, rules = null) {
    const errors = [];
    if (!rules) {
      rules = metadata.get(metadataKey, object);
    }
    if (!rules) {
      // no rules defined for propertyName.
      return errors;
    }
    rules = rules.rules;
    for (let i = 0, ii = rules.length; i < ii; i++) {
      const ruleInfo = rules[i];
      if (propertyName !== null && ruleInfo.key !== propertyName) {
        continue;
      }
      const { name, config } = ruleInfo.rule;
      const validator = { [propertyName]: { [name]: config } };
      const result = validate(object, validator);
      if (result) {
        errors.push(new ValidationError(ruleInfo.rule, result[propertyName][0], object, propertyName));

const deco = (target: DependencyCtor & { inject?: any }) => {
    if (!target.hasOwnProperty('inject')) {
      target.inject = (
        (metadata.getOwn(metadata.paramTypes, target) as Array) ||
        _emptyParameters
      ).slice();
      if (target.inject && target.inject.length > 0) {
        // TypeScript 3.0 metadata for "...rest" gives type "Object"
        // if last parameter is "Object", assume it's a ...rest and remove that
        // metadata.
        if (target.inject[target.inject.length - 1] === Object) {
          target.inject.splice(-1, 1);
        }
      }
    }
  };

let deco = function(target) {
    if (!target.hasOwnProperty('inject')) {
      target.inject = (metadata.getOwn(metadata.paramTypes, target) || _emptyParameters).slice();
      // TypeScript 3.0 metadata for "...rest" gives type "Object"
      // if last parameter is "Object", assume it's a ...rest and remove that metadata.
      if (target.inject.length > 0 &&
          target.inject[target.inject.length - 1] === Object) {
        target.inject.pop();
      }
    }
  };

//no convention and no customeElement or customAttribute but behavior added by other metadata
          resourceTypeMeta.elementName = _hyphenate(impl.name);
        }
      }
    } else {
      resourceTypeMeta = ViewResources.convention(impl)
        || HtmlBehaviorResource.convention(impl.name)
        || ValueConverterResource.convention(impl.name)
        || BindingBehaviorResource.convention(impl.name)
        || ViewEngineHooksResource.convention(impl.name);
      if (!resourceTypeMeta) {
        // doesn't match any convention, and is an exported value => custom element
        resourceTypeMeta = new HtmlBehaviorResource();
        resourceTypeMeta.elementName = _hyphenate(impl.name);
      }
      metadata.define(metadata.resource, resourceTypeMeta, impl);
    }
    resourceTypeMeta.initialize(container, impl);
    resourceTypeMeta.register(this);
    return resourceTypeMeta;
  }
}

function getObserver(instance, name) {
  let lookup = instance.__observers__;

  if (lookup === undefined) {
    // We need to lookup the actual behavior for this instance,
    // as it might be a derived class (and behavior) rather than
    // the class (and behavior) that declared the property calling getObserver().
    // This means we can't capture the behavior in property get/set/getObserver and pass it here.
    // Note that it's probably for the best, as passing the behavior is an overhead
    // that is only useful in the very first call of the first property of the instance.
    let ctor = Object.getPrototypeOf(instance).constructor; // Playing safe here, user could have written to instance.constructor.
    let behavior = metadata.get(metadata.resource, ctor);
    if (!behavior.isInitialized) {
      behavior.initialize(Container.instance || new Container(), instance.constructor);
    }

    lookup = behavior.observerLocator.getOrCreateObserversLookup(instance);
    behavior._ensurePropertiesDefined(instance, lookup);
  }

  return lookup[name];
}

it('should define metadata using something else', () => {
    let behaviorResource = new class FakeResource{}();
    @resource(behaviorResource)
    class El {}
    expect(El.$resource).toBe(undefined);
    expect(metadata.getOwn(metadata.resource, El)).toBe(behaviorResource);
  });
});

var deco = function(target){
    Metadata.on(target).add(new ElementConfigResource());
  };