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PaginatedListState.ts
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PaginatedListState.ts
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import app from '../../common/app';
import Model from '../Model';
import { ApiQueryParamsPlural, ApiResponsePlural } from '../Store';
export interface Page<TModel> {
number: number;
items: TModel[];
hasPrev?: boolean;
hasNext?: boolean;
}
export interface PaginationLocation {
page: number;
startIndex?: number;
endIndex?: number;
}
export interface PaginatedListParams {
[key: string]: any;
}
export interface PaginatedListRequestParams extends Omit<ApiQueryParamsPlural, 'include'> {
include?: string | string[];
}
export default abstract class PaginatedListState<T extends Model, P extends PaginatedListParams = PaginatedListParams> {
protected location!: PaginationLocation;
protected pageSize: number;
protected pages: Page<T>[] = [];
protected params: P = {} as P;
protected initialLoading: boolean = false;
protected loadingPrev: boolean = false;
protected loadingNext: boolean = false;
protected constructor(params: P = {} as P, page: number = 1, pageSize: number = 20) {
this.params = params;
this.location = { page };
this.pageSize = pageSize;
}
abstract get type(): string;
public clear(): void {
this.pages = [];
m.redraw();
}
public loadPrev(): Promise<void> {
if (this.loadingPrev || this.getLocation().page === 1) return Promise.resolve();
this.loadingPrev = true;
const page: number = this.getPrevPageNumber();
return this.loadPage(page)
.then(this.parseResults.bind(this, page))
.finally(() => (this.loadingPrev = false));
}
public loadNext(): Promise<void> {
if (this.loadingNext) return Promise.resolve();
this.loadingNext = true;
const page: number = this.getNextPageNumber();
return this.loadPage(page)
.then(this.parseResults.bind(this, page))
.finally(() => (this.loadingNext = false));
}
protected parseResults(pg: number, results: ApiResponsePlural<T>): void {
const pageNum = Number(pg);
const links = results.payload?.links;
const page = {
number: pageNum,
items: results,
hasNext: !!links?.next,
hasPrev: !!links?.prev,
};
if (this.isEmpty() || pageNum > this.getNextPageNumber() - 1) {
this.pages.push(page);
} else {
this.pages.unshift(page);
}
this.location = { page: pageNum };
m.redraw();
}
/**
* Load a new page of results.
*/
protected loadPage(page = 1): Promise<ApiResponsePlural<T>> {
const reqParams = this.requestParams();
const include = Array.isArray(reqParams.include) ? reqParams.include.join(',') : reqParams.include;
const params: ApiQueryParamsPlural = {
...reqParams,
page: {
...reqParams.page,
offset: this.pageSize * (page - 1),
},
include,
};
return app.store.find<T[]>(this.type, params);
}
/**
* Get the parameters that should be passed in the API request.
* Do not include page offset unless subclass overrides loadPage.
*
* @abstract
* @see loadPage
*/
protected requestParams(): PaginatedListRequestParams {
return this.params;
}
/**
* Update the `this.params` object, calling `refresh` if they have changed.
* Use `requestParams` for converting `this.params` into API parameters
*
* @param newParams
* @param page
* @see requestParams
*/
public refreshParams(newParams: P, page: number): Promise<void> {
if (this.isEmpty() || this.paramsChanged(newParams)) {
this.params = newParams;
return this.refresh(page);
}
return Promise.resolve();
}
public refresh(page: number = 1): Promise<void> {
this.initialLoading = true;
this.loadingPrev = false;
this.loadingNext = false;
this.clear();
this.location = { page };
return this.loadPage()
.then((results) => {
this.pages = [];
this.parseResults(this.location.page, results);
})
.finally(() => (this.initialLoading = false));
}
public getPages(): Page<T>[] {
return this.pages;
}
public getLocation(): PaginationLocation {
return this.location;
}
public isLoading(): boolean {
return this.initialLoading || this.loadingNext || this.loadingPrev;
}
public isInitialLoading(): boolean {
return this.initialLoading;
}
public isLoadingPrev(): boolean {
return this.loadingPrev;
}
public isLoadingNext(): boolean {
return this.loadingNext;
}
/**
* Returns true when the number of items across all loaded pages is not 0.
*
* @see isEmpty
*/
public hasItems(): boolean {
return !!this.getAllItems().length;
}
/**
* Returns true when there aren't any items *and* the state has already done its initial loading.
* If you want to know whether there are items regardless of load state, use `hasItems()` instead
*
* @see hasItems
*/
public isEmpty(): boolean {
return !this.isInitialLoading() && !this.hasItems();
}
public hasPrev(): boolean {
return !!this.pages[0]?.hasPrev;
}
public hasNext(): boolean {
return !!this.pages[this.pages.length - 1]?.hasNext;
}
/**
* Stored state parameters.
*/
public getParams(): P {
return this.params;
}
protected getNextPageNumber(): number {
const pg = this.pages[this.pages.length - 1]?.number;
if (pg && !isNaN(pg)) {
return pg + 1;
} else {
return this.location.page;
}
}
protected getPrevPageNumber(): number {
const pg = this.pages[0]?.number;
if (pg && !isNaN(pg)) {
// If the calculated page number is less than 1,
// return 1 as the prev page (first possible page number)
return Math.max(pg - 1, 1);
} else {
return this.location.page;
}
}
protected paramsChanged(newParams: P): boolean {
return Object.keys(newParams).some((key) => this.getParams()[key] !== newParams[key]);
}
protected getAllItems(): T[] {
return this.getPages()
.map((pg) => pg.items)
.flat();
}
}