feat(core): support asynchronous deserializers

We now support deserializers which run asynchronously by returning an
observable instead. This is useful when the deserializer relies on some
asynchronous process or data which has to be fetched first.

relates #93

Signed-off-by: Ingo Bürk <[email protected]>

projects/ngqp-demo/src/app/docs-items/configuration/query-param/query-param-configuration-docs.component.html

@@ -20,6 +20,18 @@ <h2>Serializing and deserializing</h2>
         provide your own (de-)serializers, you can pass them to <span apiDocsLink>QueryParamBuilder#param</span>.
     </p>
     <demo-serializer-example></demo-serializer-example>
+    <div class="alert alert-info">
+        <p>
+            Deserializers can also be asynchronous by returning an Observable instead. This can be useful, e.g., if you
+            have a user's name in the URL and need to deserialize it into a user object, but fetching the list of users
+            is an asynchronous operation.
+        </p>
+        <p>
+            Note that for asynchronous deserializers, ngqp will use the <em>first</em> emitted value rather than the
+            last one. Furthermore, the <code>valueChanges</code> observables will only emit after the deserializer has
+            emitted.
+        </p>
+    </div>
 
     <docs-fragment fragment="multi">
         <h2>Components with multiple values</h2>

projects/ngqp-demo/src/app/home/home.component.ts

@@ -1,5 +1,5 @@
 import { Component } from '@angular/core';
-import { createStringDeserializer, QueryParamBuilder, QueryParamGroup } from '@ngqp/core';
+import { QueryParamBuilder, QueryParamGroup } from '@ngqp/core';
 import { faAlignLeft, faCogs, faGlassCheers, faHeart, IconDefinition } from '@fortawesome/free-solid-svg-icons';
 import { faGithub } from '@fortawesome/free-brands-svg-icons';
 

projects/ngqp/core/src/lib/directives/query-param-group.service.ts

@@ -1,6 +1,6 @@
 import { Inject, Injectable, isDevMode, OnDestroy, Optional } from '@angular/core';
 import { Params } from '@angular/router';
-import { EMPTY, from, Observable, Subject, zip } from 'rxjs';
+import { EMPTY, forkJoin, from, Observable, Subject, zip } from 'rxjs';
 import {
     catchError,
     concatMap,
@@ -15,7 +15,7 @@ import {
 } from 'rxjs/operators';
 import { compareParamMaps, filterParamMap, isMissing, isPresent, NOP } from '../util';
 import { QueryParamGroup } from '../model/query-param-group';
-import { MultiQueryParam, QueryParam, PartitionedQueryParam } from '../model/query-param';
+import { MultiQueryParam, PartitionedQueryParam, QueryParam } from '../model/query-param';
 import { NGQP_ROUTER_ADAPTER, NGQP_ROUTER_OPTIONS, RouterAdapter, RouterOptions } from '../router-adapter/router-adapter.interface';
 import { QueryParamAccessor } from './query-param-accessor.interface';
 
@@ -226,32 +226,49 @@ export class QueryParamGroupService implements OnDestroy {
                     return compareParamMaps(filterParamMap(previousMap, keys), filterParamMap(currentMap, keys));
                 }),
             )),
-            takeUntil(this.destroy$),
-        ).subscribe(queryParamMap => {
-            const synthetic = this.isSyntheticNavigation();
-            const groupValue: Record<string, unknown> = {};
-
-            Object.keys(this.getQueryParamGroup().queryParams).forEach(queryParamName => {
-                const partitionedQueryParam = this.getQueryParamAsPartition(queryParamName);
-                const newValues = partitionedQueryParam.queryParams.map(queryParam => isMultiQueryParam<unknown>(queryParam)
-                    ? queryParam.deserializeValue(queryParamMap.getAll(queryParam.urlParam))
-                    : queryParam.deserializeValue(queryParamMap.get(queryParam.urlParam))
+            switchMap(queryParamMap => {
+                // We need to capture this right here since this is only set during the on-going navigation.
+                const synthetic = this.isSyntheticNavigation();
+                const queryParamNames = Object.keys(this.getQueryParamGroup().queryParams);
+
+                return forkJoin<Record<string, unknown>>(...queryParamNames
+                    .map(queryParamName => {
+                        const partitionedQueryParam = this.getQueryParamAsPartition(queryParamName);
+
+                        return forkJoin<unknown>(...partitionedQueryParam.queryParams
+                            .map(queryParam => isMultiQueryParam<unknown>(queryParam)
+                                ? queryParam.deserializeValue(queryParamMap.getAll(queryParam.urlParam))
+                                : queryParam.deserializeValue(queryParamMap.get(queryParam.urlParam))
+                            )
+                        ).pipe(
+                            map(newValues => partitionedQueryParam.reduce(newValues)),
+                            tap(newValue => {
+                                const directives = this.directives.get(queryParamName);
+                                if (directives) {
+                                    directives.forEach(directive => directive.valueAccessor.writeValue(newValue));
+                                }
+                            }),
+                            map(newValue => {
+                                return { [ queryParamName ]: newValue };
+                            }),
+                            takeUntil(this.destroy$),
+                        );
+                    })
+                ).pipe(
+                    map((values: Record<string, unknown>[]) => values.reduce((groupValue, value) => {
+                        return {
+                            ...groupValue,
+                            ...value,
+                        };
+                    }, {})),
+                    tap(groupValue => this.getQueryParamGroup().setValue(groupValue, {
+                        emitEvent: !synthetic,
+                        emitModelToViewChange: false,
+                    })),
                 );
-                const newValue = partitionedQueryParam.reduce(newValues);
-
-                const directives = this.directives.get(queryParamName);
-                if (directives) {
-                    directives.forEach(directive => directive.valueAccessor.writeValue(newValue));
-                }
-
-                groupValue[ queryParamName ] = newValue;
-            });
-
-            this.getQueryParamGroup().setValue(groupValue, {
-                emitEvent: !synthetic,
-                emitModelToViewChange: false,
-            });
-        });
+            }),
+            takeUntil(this.destroy$),
+        ).subscribe();
     }
 
     /** Listens for newly added parameters and starts synchronization for them. */
@@ -350,7 +367,7 @@ export class QueryParamGroupService implements OnDestroy {
 
         return {
             ...(this.globalRouterOptions || {}),
-            ...groupOptions,
+            ...(groupOptions || {}),
         };
     }
 

projects/ngqp/core/src/lib/model/query-param.ts

@@ -1,5 +1,6 @@
-import { Observable, Subject } from 'rxjs';
-import { areEqualUsing, isFunction, isMissing, isPresent, undefinedToNull, wrapTryCatch } from '../util';
+import { forkJoin, isObservable, Observable, of, Subject } from 'rxjs';
+import { first } from 'rxjs/operators';
+import { areEqualUsing, isFunction, isMissing, isPresent, undefinedToNull, wrapIntoObservable, wrapTryCatch } from '../util';
 import { Comparator, OnChangeFunction, ParamCombinator, ParamDeserializer, ParamSerializer, Partitioner, Reducer } from '../types';
 import { QueryParamGroup } from './query-param-group';
 import { MultiQueryParamOpts, PartitionedQueryParamOpts, QueryParamOpts, QueryParamOptsBase } from './query-param-opts';
@@ -117,12 +118,6 @@ export abstract class AbstractQueryParam<U, T> extends AbstractQueryParamBase<T>
         this.combineWith = combineWith;
     }
 
-    /** @internal */
-    public abstract serializeValue(value: T | null): (string | null) | (string | null)[];
-
-    /** @internal */
-    public abstract deserializeValue(value: (string | null) | (string | null)[]): T | null;
-
     /**
      * Updates the value of this parameter.
      *
@@ -180,12 +175,12 @@ export class QueryParam<T> extends AbstractQueryParam<T | null, T | null> implem
     }
 
     /** @internal */
-    public deserializeValue(value: string | null): T | null {
+    public deserializeValue(value: string | null): Observable<T | null> {
         if (this.emptyOn !== undefined && value === null) {
-            return this.emptyOn;
+            return of(this.emptyOn);
         }
 
-        return this.deserialize(value);
+        return wrapIntoObservable(this.deserialize(value)).pipe(first());
     }
 
 }
@@ -212,12 +207,14 @@ export class MultiQueryParam<T> extends AbstractQueryParam<T | null, (T | null)[
     }
 
     /** @internal */
-    public deserializeValue(value: (string | null)[] | null): (T | null)[] | null {
-        if (this.emptyOn !== undefined && (value || []).length === 0) {
-            return this.emptyOn;
+    public deserializeValue(values: (string | null)[] | null): Observable<(T | null)[] | null> {
+        if (this.emptyOn !== undefined && (values || []).length === 0) {
+            return of(this.emptyOn);
         }
 
-        return (value || []).map(this.deserialize.bind(this));
+        return forkJoin<T | null>(...(values || [])
+            .map(value => wrapIntoObservable(this.deserialize(value)).pipe(first()))
+        );
     }
 
 }

projects/ngqp/core/src/lib/types.ts

@@ -1,4 +1,5 @@
 import { Params } from '@angular/router';
+import { Observable } from 'rxjs';
 
 /**
  * A serializer defines how the represented form control's
@@ -10,7 +11,7 @@ export type ParamSerializer<T> = (model: T | null) => string | null;
  * A deserializer defines how a URL parameter is converted
  * into the represented form control's value.
  */
-export type ParamDeserializer<T> = (value: string | null) => T | null;
+export type ParamDeserializer<T> = (value: string | null) => (T | null) | Observable<T | null>;
 
 /**
  * A partitioner can split a value into an array of parts.

projects/ngqp/core/src/lib/util.spec.ts

@@ -1,4 +1,5 @@
 import { convertToParamMap, Params } from '@angular/router';
+import { of } from 'rxjs';
 import {
     areEqualUsing,
     compareParamMaps,
@@ -9,6 +10,7 @@ import {
     isPresent,
     LOOSE_IDENTITY_COMPARATOR,
     undefinedToNull,
+    wrapIntoObservable,
     wrapTryCatch
 } from './util';
 import { Comparator } from './types';
@@ -266,4 +268,27 @@ describe(compareParamMaps.name, () => {
             { a: [ 'a2', 'a1' ] },
         )).toBe(true);
     });
+});
+
+describe(wrapIntoObservable.name, async () => {
+    it('wraps null', async () => {
+        const obs$ = wrapIntoObservable(null);
+        expect(obs$).toBeDefined();
+
+        obs$.subscribe(v => expect(v).toBe(null));
+    });
+
+    it('wraps a primitive value', async () => {
+        const obs$ = wrapIntoObservable(42);
+        expect(obs$).toBeDefined();
+
+        obs$.subscribe(v => expect(v).toBe(42));
+    });
+
+    it('does not wrap an observable', async () => {
+        const obs$ = wrapIntoObservable(of(42));
+        expect(obs$).toBeDefined();
+
+        obs$.subscribe(v => expect(v).toBe(42));
+    });
 });

projects/ngqp/core/src/lib/util.ts

@@ -1,4 +1,5 @@
 import { convertToParamMap, ParamMap, Params } from '@angular/router';
+import { isObservable, Observable, of } from 'rxjs';
 import { Comparator } from './types';
 
 /** @internal */
@@ -96,4 +97,13 @@ export function compareStringArraysUnordered(first: string[], second: string[]):
     const sortedFirst = first.sort();
     const sortedSecond = second.sort();
     return sortedFirst.every((firstKey, index) => firstKey === sortedSecond[index]);
+}
+
+/** @internal */
+export function wrapIntoObservable<T>(input: T | Observable<T>): Observable<T> {
+    if (isObservable(input)) {
+        return input;
+    }
+
+    return of(input);
 }

projects/ngqp/core/src/test/serialize-deserialize.spec.ts

@@ -2,6 +2,8 @@ import { Component } from '@angular/core';
 import { Router } from '@angular/router';
 import { async, ComponentFixture, fakeAsync, TestBed, tick } from '@angular/core/testing';
 import { RouterTestingModule } from '@angular/router/testing';
+import { of } from 'rxjs';
+import { delay } from 'rxjs/operators';
 import { QueryParamBuilder, QueryParamGroup, QueryParamModule } from '../public_api';
 import { setupNavigationWarnStub } from './util';
 
@@ -27,6 +29,28 @@ class BasicTestComponent {
 
 }
 
+@Component({
+    template: `
+        <div [queryParamGroup]="paramGroup">
+            <input type="text" queryParamName="param" />
+        </div>
+    `,
+})
+class AsyncTestComponent {
+
+    public paramGroup: QueryParamGroup;
+
+    constructor(private qpb: QueryParamBuilder) {
+        this.paramGroup = qpb.group({
+            param: qpb.stringParam('q', {
+                serialize: value => value ? value.toUpperCase() : null,
+                deserialize: value => of(value ? value.toLowerCase() : null).pipe(delay(500)),
+            }),
+        });
+    }
+
+}
+
 describe('(de-)serialize', () => {
     let fixture: ComponentFixture<BasicTestComponent>;
     let component: BasicTestComponent;
@@ -72,6 +96,50 @@ describe('(de-)serialize', () => {
         router.navigateByUrl('/?q=TEST');
         tick();
 
+        expect(input.value).toBe('test');
+    }));
+});
+
+describe('asynchronous (de-)serialize', () => {
+    let fixture: ComponentFixture<AsyncTestComponent>;
+    let component: AsyncTestComponent;
+    let input: HTMLInputElement;
+    let router: Router;
+
+    beforeEach(() => setupNavigationWarnStub());
+
+    beforeEach(async(() => {
+        TestBed.configureTestingModule({
+            imports: [
+                RouterTestingModule.withRoutes([]),
+                QueryParamModule,
+            ],
+            declarations: [
+                AsyncTestComponent,
+            ],
+        });
+
+        router = TestBed.get(Router);
+        TestBed.compileComponents();
+        router.initialNavigation();
+    }));
+
+    beforeEach(() => {
+        fixture = TestBed.createComponent(AsyncTestComponent);
+        component = fixture.componentInstance;
+        fixture.detectChanges();
+
+        input = (fixture.nativeElement as HTMLElement).querySelector('input') as HTMLInputElement;
+        fixture.detectChanges();
+    });
+
+    it('applies the async deserializer when the URL changes', fakeAsync(() => {
+        router.navigateByUrl('/?q=TEST');
+
+        tick();
+        expect(input.value).toBe('');
+
+        tick(500);
         expect(input.value).toBe('test');
     }));
 });