feat(entity) New stategy to filter entities with a custom function. (#…

…663)

packages/common/src/lib/entity/shared/entity.interfaces.ts

@@ -31,6 +31,10 @@ export interface EntityStateManagerOptions {
 
 export interface EntityStoreStrategyOptions {}
 
+export interface EntityStoreStrategyFuncOptions extends EntityStoreStrategyOptions {
+  filterClauseFunc: EntityFilterClause;
+}
+
 export interface EntityTransactionOptions {
   getKey?: (entity: object) => EntityKey;
 }

packages/common/src/lib/entity/shared/strategies/filter-custom-function.ts

@@ -0,0 +1,91 @@
+import { EntityStoreStrategyFuncOptions } from '../entity.interfaces';
+import { EntityStore } from '../store';
+import { EntityStoreStrategy } from './strategy';
+
+/**
+ * When active, this strategy filters a store's stateView to return
+ * selected entities only.
+ */
+export class EntityStoreFilterCustomFuncStrategy extends EntityStoreStrategy {
+
+  constructor(protected options: EntityStoreStrategyFuncOptions) {
+    super(options);
+  }
+
+  /**
+   * Store / filter ids map
+   */
+  private filters: Map<EntityStore, string> = new Map();
+
+  /**
+   * Bind this strategy to a store and start filtering it
+   * @param store Entity store
+   */
+  bindStore(store: EntityStore) {
+    super.bindStore(store);
+    if (this.active === true) {
+      this.filterStore(store);
+    }
+  }
+
+  /**
+   * Unbind this strategy from a store and stop filtering it
+   * @param store Entity store
+   */
+  unbindStore(store: EntityStore) {
+    super.unbindStore(store);
+    if (this.active === true) {
+      this.unfilterStore(store);
+    }
+  }
+
+  /**
+   * Start filtering all stores
+   * @internal
+   */
+  protected doActivate() {
+    this.filterAll();
+  }
+
+  /**
+   * Stop filtering all stores
+   * @internal
+   */
+  protected doDeactivate() {
+    this.unfilterAll();
+  }
+
+  /**
+   * Filter all stores
+   */
+  private filterAll() {
+    this.stores.forEach((store: EntityStore) => this.filterStore(store));
+  }
+
+  /**
+   * Unfilter all stores
+   */
+  private unfilterAll() {
+    this.stores.forEach((store: EntityStore) => this.unfilterStore(store));
+  }
+
+  /**
+   * Filter a store and add it to the filters map
+   */
+  private filterStore(store: EntityStore) {
+    this.filters.set(store, store.stateView.addFilter(this.options.filterClauseFunc));
+  }
+
+  /**
+   * Unfilter a store and delete it from the filters map
+   */
+  private unfilterStore(store: EntityStore) {
+    const filterId = this.filters.get(store);
+    if (filterId === undefined) {
+      return;
+    }
+
+    store.stateView.removeFilter(filterId);
+    this.filters.delete(store);
+  }
+}

packages/common/src/lib/entity/shared/strategies/index.ts

@@ -1,2 +1,3 @@
 export * from './strategy';
+export * from './filter-custom-function';
 export * from './filter-selection';