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dspace-angular/src/app/core/data/base/base-data.service.ts

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TypeScript

/**
* The contents of this file are subject to the license and copyright
* detailed in the LICENSE and NOTICE files at the root of the source
* tree and available online at
*
* http://www.dspace.org/license/
*/
import { AsyncSubject, from as observableFrom, Observable, of as observableOf } from 'rxjs';
import { map, mergeMap, skipWhile, switchMap, take, tap, toArray } from 'rxjs/operators';
import { hasValue, isNotEmpty, isNotEmptyOperator } from '../../../shared/empty.util';
import { FollowLinkConfig } from '../../../shared/utils/follow-link-config.model';
import { RemoteDataBuildService } from '../../cache/builders/remote-data-build.service';
import { RequestParam } from '../../cache/models/request-param.model';
import { HALEndpointService } from '../../shared/hal-endpoint.service';
import { URLCombiner } from '../../url-combiner/url-combiner';
import { RemoteData } from '../remote-data';
import { GetRequest } from '../request.models';
import { RequestService } from '../request.service';
import { CacheableObject } from '../../cache/cacheable-object.model';
import { FindListOptions } from '../find-list-options.model';
import { PaginatedList } from '../paginated-list.model';
import { ObjectCacheEntry } from '../../cache/object-cache.reducer';
import { ObjectCacheService } from '../../cache/object-cache.service';
import { HALDataService } from './hal-data-service.interface';
import { getFirstCompletedRemoteData } from '../../shared/operators';
export const EMBED_SEPARATOR = '%2F';
/**
* Common functionality for data services.
* Specific functionality that not all services would need
* is implemented in "DataService feature" classes (e.g. {@link CreateData}
*
* All DataService (or DataService feature) classes must
* - extend this class (or {@link IdentifiableDataService})
* - implement any DataService features it requires in order to forward calls to it
*
* ```
* export class SomeDataService extends BaseDataService<Something> implements CreateData<Something>, SearchData<Something> {
* private createData: CreateData<Something>;
* private searchData: SearchDataData<Something>;
*
* create(...) {
* return this.createData.create(...);
* }
*
* searchBy(...) {
* return this.searchData.searchBy(...);
* }
* }
* ```
*/
export class BaseDataService<T extends CacheableObject> implements HALDataService<T> {
constructor(
protected linkPath: string,
protected requestService: RequestService,
protected rdbService: RemoteDataBuildService,
protected objectCache: ObjectCacheService,
protected halService: HALEndpointService,
protected responseMsToLive?: number,
) {
}
/**
* Allows subclasses to reset the response cache time.
*/
/**
* Get the endpoint for browsing
* @param options The [[FindListOptions]] object
* @param linkPath The link path for the object
* @returns {Observable<string>}
*/
getBrowseEndpoint(options: FindListOptions = {}, linkPath?: string): Observable<string> {
return this.getEndpoint();
}
/**
* Get the base endpoint for all requests
*/
protected getEndpoint(): Observable<string> {
return this.halService.getEndpoint(this.linkPath);
}
/**
* Turn an options object into a query string and combine it with the given HREF
*
* @param href The HREF to which the query string should be appended
* @param options The [[FindListOptions]] object
* @param extraArgs Array with additional params to combine with query string
* @return {Observable<string>}
* Return an observable that emits created HREF
* @param linksToFollow List of {@link FollowLinkConfig} that indicate which {@link HALLink}s should be automatically resolved
*/
public buildHrefFromFindOptions(href: string, options: FindListOptions, extraArgs: string[] = [], ...linksToFollow: FollowLinkConfig<T>[]): string {
let args = [...extraArgs];
if (hasValue(options.currentPage) && typeof options.currentPage === 'number') {
/* TODO: this is a temporary fix for the pagination start index (0 or 1) discrepancy between the rest and the frontend respectively */
args = this.addHrefArg(href, args, `page=${options.currentPage - 1}`);
}
if (hasValue(options.elementsPerPage)) {
args = this.addHrefArg(href, args, `size=${options.elementsPerPage}`);
}
if (hasValue(options.sort)) {
args = this.addHrefArg(href, args, `sort=${options.sort.field},${options.sort.direction}`);
}
if (hasValue(options.startsWith)) {
args = this.addHrefArg(href, args, `startsWith=${options.startsWith}`);
}
if (hasValue(options.searchParams)) {
options.searchParams.forEach((param: RequestParam) => {
args = this.addHrefArg(href, args, `${param.fieldName}=${param.fieldValue}`);
});
}
args = this.addEmbedParams(href, args, ...linksToFollow);
if (isNotEmpty(args)) {
return new URLCombiner(href, `?${args.join('&')}`).toString();
} else {
return href;
}
}
/**
* Turn an array of RequestParam into a query string and combine it with the given HREF
*
* @param href The HREF to which the query string should be appended
* @param params Array with additional params to combine with query string
* @param linksToFollow List of {@link FollowLinkConfig} that indicate which {@link HALLink}s should be automatically resolved
*
* @return {Observable<string>}
* Return an observable that emits created HREF
*/
buildHrefWithParams(href: string, params: RequestParam[], ...linksToFollow: FollowLinkConfig<T>[]): string {
let args = [];
if (hasValue(params)) {
params.forEach((param: RequestParam) => {
args = this.addHrefArg(href, args, `${param.fieldName}=${param.fieldValue}`);
});
}
args = this.addEmbedParams(href, args, ...linksToFollow);
if (isNotEmpty(args)) {
return new URLCombiner(href, `?${args.join('&')}`).toString();
} else {
return href;
}
}
/**
* Adds the embed options to the link for the request
* @param href The href the params are to be added to
* @param args params for the query string
* @param linksToFollow links we want to embed in query string if shouldEmbed is true
*/
protected addEmbedParams(href: string, args: string[], ...linksToFollow: FollowLinkConfig<T>[]) {
linksToFollow.forEach((linkToFollow: FollowLinkConfig<T>) => {
if (hasValue(linkToFollow) && linkToFollow.shouldEmbed) {
const embedString = 'embed=' + String(linkToFollow.name);
// Add the embeds size if given in the FollowLinkConfig.FindListOptions
if (hasValue(linkToFollow.findListOptions) && hasValue(linkToFollow.findListOptions.elementsPerPage)) {
args = this.addHrefArg(href, args,
'embed.size=' + String(linkToFollow.name) + '=' + linkToFollow.findListOptions.elementsPerPage);
}
// Adds the nested embeds and their size if given
if (isNotEmpty(linkToFollow.linksToFollow)) {
args = this.addNestedEmbeds(embedString, href, args, ...linkToFollow.linksToFollow);
} else {
args = this.addHrefArg(href, args, embedString);
}
}
});
return args;
}
/**
* Add a new argument to the list of arguments, only if it doesn't already exist in the given href,
* or the current list of arguments
*
* @param href The href the arguments are to be added to
* @param currentArgs The current list of arguments
* @param newArg The new argument to add
* @return The next list of arguments, with newArg included if it wasn't already.
* Note this function will not modify any of the input params.
*/
protected addHrefArg(href: string, currentArgs: string[], newArg: string): string[] {
if (href.includes(newArg) || currentArgs.includes(newArg)) {
return [...currentArgs];
} else {
return [...currentArgs, newArg];
}
}
/**
* Add the nested followLinks to the embed param, separated by a /, and their sizes, recursively
* @param embedString embedString so far (recursive)
* @param href The href the params are to be added to
* @param args params for the query string
* @param linksToFollow links we want to embed in query string if shouldEmbed is true
*/
protected addNestedEmbeds(embedString: string, href: string, args: string[], ...linksToFollow: FollowLinkConfig<T>[]): string[] {
let nestEmbed = embedString;
linksToFollow.forEach((linkToFollow: FollowLinkConfig<T>) => {
if (hasValue(linkToFollow) && linkToFollow.shouldEmbed) {
nestEmbed = nestEmbed + EMBED_SEPARATOR + String(linkToFollow.name);
// Add the nested embeds size if given in the FollowLinkConfig.FindListOptions
if (hasValue(linkToFollow.findListOptions) && hasValue(linkToFollow.findListOptions.elementsPerPage)) {
const nestedEmbedSize = 'embed.size=' + nestEmbed.split('=')[1] + '=' + linkToFollow.findListOptions.elementsPerPage;
args = this.addHrefArg(href, args, nestedEmbedSize);
}
if (hasValue(linkToFollow.linksToFollow) && isNotEmpty(linkToFollow.linksToFollow)) {
args = this.addNestedEmbeds(nestEmbed, href, args, ...linkToFollow.linksToFollow);
} else {
args = this.addHrefArg(href, args, nestEmbed);
}
}
});
return args;
}
/**
* An operator that will call the given function if the incoming RemoteData is stale and
* shouldReRequest is true
*
* @param shouldReRequest Whether or not to call the re-request function if the RemoteData is stale
* @param requestFn The function to call if the RemoteData is stale and shouldReRequest is
* true
*/
protected reRequestStaleRemoteData<O>(shouldReRequest: boolean, requestFn: () => Observable<RemoteData<O>>) {
return (source: Observable<RemoteData<O>>): Observable<RemoteData<O>> => {
if (shouldReRequest === true) {
return source.pipe(
tap((remoteData: RemoteData<O>) => {
if (hasValue(remoteData) && remoteData.isStale) {
requestFn();
}
})
);
} else {
return source;
}
};
}
/**
* Returns an observable of {@link RemoteData} of an object, based on an href, with a list of
* {@link FollowLinkConfig}, to automatically resolve {@link HALLink}s of the object
* @param href$ The url of object we want to retrieve. Can be a string or
* an Observable<string>
* @param useCachedVersionIfAvailable If this is true, the request will only be sent if there's
* no valid cached version. Defaults to true
* @param reRequestOnStale Whether or not the request should automatically be re-
* requested after the response becomes stale
* @param linksToFollow List of {@link FollowLinkConfig} that indicate which
* {@link HALLink}s should be automatically resolved
*/
findByHref(href$: string | Observable<string>, useCachedVersionIfAvailable = true, reRequestOnStale = true, ...linksToFollow: FollowLinkConfig<T>[]): Observable<RemoteData<T>> {
if (typeof href$ === 'string') {
href$ = observableOf(href$);
}
const requestHref$ = href$.pipe(
isNotEmptyOperator(),
take(1),
map((href: string) => this.buildHrefFromFindOptions(href, {}, [], ...linksToFollow)),
);
this.createAndSendGetRequest(requestHref$, useCachedVersionIfAvailable);
return this.rdbService.buildSingle<T>(requestHref$, ...linksToFollow).pipe(
// This skip ensures that if a stale object is present in the cache when you do a
// call it isn't immediately returned, but we wait until the remote data for the new request
// is created. If useCachedVersionIfAvailable is false it also ensures you don't get a
// cached completed object
skipWhile((rd: RemoteData<T>) => useCachedVersionIfAvailable ? rd.isStale : rd.hasCompleted),
this.reRequestStaleRemoteData(reRequestOnStale, () =>
this.findByHref(href$, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow)),
);
}
/**
* Returns an Observable of a {@link RemoteData} of a {@link PaginatedList} of objects, based on an href,
* with a list of {@link FollowLinkConfig}, to automatically resolve {@link HALLink}s of the object
*
* @param href$ The url of list we want to retrieve. Can be a string or an Observable<string>
* @param options
* @param useCachedVersionIfAvailable If this is true, the request will only be sent if there's no valid cached version.
* @param reRequestOnStale Whether or not the request should automatically be re-requested after the response becomes stale
* @param linksToFollow List of {@link FollowLinkConfig} that indicate which {@link HALLink}s should be automatically resolved
*/
findListByHref(href$: string | Observable<string>, options: FindListOptions = {}, useCachedVersionIfAvailable = true, reRequestOnStale = true, ...linksToFollow: FollowLinkConfig<T>[]): Observable<RemoteData<PaginatedList<T>>> {
if (typeof href$ === 'string') {
href$ = observableOf(href$);
}
const requestHref$ = href$.pipe(
isNotEmptyOperator(),
take(1),
map((href: string) => this.buildHrefFromFindOptions(href, options, [], ...linksToFollow)),
);
this.createAndSendGetRequest(requestHref$, useCachedVersionIfAvailable);
return this.rdbService.buildList<T>(requestHref$, ...linksToFollow).pipe(
// This skip ensures that if a stale object is present in the cache when you do a
// call it isn't immediately returned, but we wait until the remote data for the new request
// is created. If useCachedVersionIfAvailable is false it also ensures you don't get a
// cached completed object
skipWhile((rd: RemoteData<PaginatedList<T>>) => useCachedVersionIfAvailable ? rd.isStale : rd.hasCompleted),
this.reRequestStaleRemoteData(reRequestOnStale, () =>
this.findListByHref(href$, options, useCachedVersionIfAvailable, reRequestOnStale, ...linksToFollow)),
);
}
/**
* Create a GET request for the given href, and send it.
*
* @param href$ The url of object we want to retrieve. Can be a string or
* an Observable<string>
* @param useCachedVersionIfAvailable If this is true, the request will only be sent if there's
* no valid cached version. Defaults to true
*/
protected createAndSendGetRequest(href$: string | Observable<string>, useCachedVersionIfAvailable = true): void {
if (isNotEmpty(href$)) {
if (typeof href$ === 'string') {
href$ = observableOf(href$);
}
href$.pipe(
isNotEmptyOperator(),
take(1)
).subscribe((href: string) => {
const requestId = this.requestService.generateRequestId();
const request = new GetRequest(requestId, href);
if (hasValue(this.responseMsToLive)) {
request.responseMsToLive = this.responseMsToLive;
}
this.requestService.send(request, useCachedVersionIfAvailable);
});
}
}
/**
* Return the links to traverse from the root of the api to the
* endpoint this DataService represents
*
* e.g. if the api root links to 'foo', and the endpoint at 'foo'
* links to 'bar' the linkPath for the BarDataService would be
* 'foo/bar'
*/
getLinkPath(): string {
return this.linkPath;
}
/**
* Shorthand method to add a dependency to a cached object
* ```
* const out$ = this.findByHref(...); // or another method that sends a request
* this.addDependency(out$, dependsOnHref);
* ```
* When {@link dependsOnHref$} is invalidated, {@link object$} will be invalidated as well.
*
*
* @param object$ the cached object
* @param dependsOnHref$ the href of the object it should depend on
*/
protected addDependency(object$: Observable<RemoteData<T | PaginatedList<T>>>, dependsOnHref$: string | Observable<string>) {
this.objectCache.addDependency(
object$.pipe(
getFirstCompletedRemoteData(),
switchMap((rd: RemoteData<T>) => {
if (rd.hasSucceeded) {
return [rd.payload._links.self.href];
} else {
// undefined href will be skipped in objectCache.addDependency
return [undefined];
}
}),
),
dependsOnHref$
);
}
/**
* Invalidate an existing DSpaceObject by marking all requests it is included in as stale
* @param href The self link of the object to be invalidated
* @return An Observable that will emit `true` once all requests are stale
*/
invalidateByHref(href: string): Observable<boolean> {
const done$ = new AsyncSubject<boolean>();
this.objectCache.getByHref(href).pipe(
take(1),
switchMap((oce: ObjectCacheEntry) => {
return observableFrom([
...oce.requestUUIDs,
...oce.dependentRequestUUIDs
]).pipe(
mergeMap((requestUUID: string) => this.requestService.setStaleByUUID(requestUUID)),
toArray(),
);
}),
).subscribe(() => {
this.objectCache.removeDependents(href);
done$.next(true);
done$.complete();
});
return done$;
}
}