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<li >PageInterceptor</li>
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<p class="comment">
<h3>File</h3>
</p>
<p class="comment">
<code>src/core/interceptors/page.interceptor.ts</code>
</p>
<p class="comment">
<h3>Description</h3>
</p>
<p class="comment">
<p>Pagination-implementing interceptor</p>
</p>
<section>
<h3 id="index">Index</h3>
<table class="table table-sm table-bordered index-table">
<tbody>
<tr>
<td class="col-md-4">
<h6><b>Properties</b></h6>
</td>
</tr>
<tr>
<td class="col-md-4">
<ul class="index-list">
<li>
<span class="modifier">Private</span>
<span class="modifier">Readonly</span>
<a href="#ES_IP" >ES_IP</a>
</li>
<li>
<span class="modifier">Private</span>
<span class="modifier">Readonly</span>
<a href="#ES_PORT" >ES_PORT</a>
</li>
</ul>
</td>
</tr>
<tr>
<td class="col-md-4">
<h6><b>Methods</b></h6>
</td>
</tr>
<tr>
<td class="col-md-4">
<ul class="index-list">
<li>
<span class="modifier">Async</span>
<a href="#deletePIT" >deletePIT</a>
</li>
<li>
<span class="modifier">Public</span>
<span class="modifier">Async</span>
<a href="#getPIT" >getPIT</a>
</li>
<li>
<span class="modifier">Async</span>
<a href="#intercept" >intercept</a>
</li>
</ul>
</td>
</tr>
</tbody>
</table>
</section>
<section>
<h3 id="constructor">Constructor</h3>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<code>constructor(httpService: HttpService, cacheManager: Cache)</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="18" class="link-to-prism">src/core/interceptors/page.interceptor.ts:18</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Injects needed dependencies and instantiates the storage object</p>
</div>
<div>
<b>Parameters :</b>
<table class="params">
<thead>
<tr>
<td>Name</td>
<td>Type</td>
<td>Optional</td>
</tr>
</thead>
<tbody>
<tr>
<td>httpService</td>
<td>
<code>HttpService</code>
</td>
<td>
No
</td>
</tr>
<tr>
<td>cacheManager</td>
<td>
<code>Cache</code>
</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</div>
</td>
</tr>
</tbody>
</table>
</section>
<section>
<h3 id="methods">
Methods
</h3>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<a name="deletePIT"></a>
<span class="name">
<span class="modifier">Async</span>
<span ><b>deletePIT</b></span>
<a href="#deletePIT"><span class="icon ion-ios-link"></span></a>
</span>
</td>
</tr>
<tr>
<td class="col-md-4">
<span class="modifier-icon icon ion-ios-reset"></span>
<code>deletePIT(pitID: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/string" target="_blank">string</a>)</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="117"
class="link-to-prism">src/core/interceptors/page.interceptor.ts:117</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Deletes the PIT specified by provided ID</p>
</div>
<div class="io-description">
<b>Parameters :</b>
<table class="params">
<thead>
<tr>
<td>Name</td>
<td>Type</td>
<td>Optional</td>
<td>Description</td>
</tr>
</thead>
<tbody>
<tr>
<td>pitID</td>
<td>
<code><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/string" target="_blank" >string</a></code>
</td>
<td>
No
</td>
<td>
<p>, ID of the PIT, that would be deleted</p>
</td>
</tr>
</tbody>
</table>
</div>
<div>
</div>
<div class="io-description">
<b>Returns : </b> <code>Promise<boolean></code>
</div>
<div class="io-description">
<p>true/false, depending on the result of deletion of the PIT</p>
</div>
</td>
</tr>
</tbody>
</table>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<a name="getPIT"></a>
<span class="name">
<span class="modifier">Public</span>
<span class="modifier">Async</span>
<span ><b>getPIT</b></span>
<a href="#getPIT"><span class="icon ion-ios-link"></span></a>
</span>
</td>
</tr>
<tr>
<td class="col-md-4">
<span class="modifier-icon icon ion-ios-reset"></span>
<code>getPIT(alive: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/number" target="_blank">number</a>, unit: <a href="../undefineds/EsTime.html" target="_self">EsTime</a>)</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="97"
class="link-to-prism">src/core/interceptors/page.interceptor.ts:97</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Acquires a PIT ID from Elasticsearch, needed for a request</p>
</div>
<div class="io-description">
<b>Parameters :</b>
<table class="params">
<thead>
<tr>
<td>Name</td>
<td>Type</td>
<td>Optional</td>
<td>Default value</td>
<td>Description</td>
</tr>
</thead>
<tbody>
<tr>
<td>alive</td>
<td>
<code><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/number" target="_blank" >number</a></code>
</td>
<td>
No
</td>
<td>
</td>
<td>
<p>, amount of time in minutes (defaults to 1). If time unit is not specified - defaults to minutes.</p>
</td>
</tr>
<tr>
<td>unit</td>
<td>
<code><a href="../miscellaneous/enumerations.html#EsTime" target="_self" >EsTime</a></code>
</td>
<td>
No
</td>
<td>
<code>EsTime.min</code>
</td>
<td>
</td>
</tr>
</tbody>
</table>
</div>
<div>
</div>
<div class="io-description">
<b>Returns : </b> <code><a href="../interfaces/EsPit.html" target="_self" >Promise<EsPit></a></code>
</div>
<div class="io-description">
<p>PIT object <EsPit> containing PIT ID and keep_alive value</p>
</div>
</td>
</tr>
</tbody>
</table>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<a name="intercept"></a>
<span class="name">
<span class="modifier">Async</span>
<span ><b>intercept</b></span>
<a href="#intercept"><span class="icon ion-ios-link"></span></a>
</span>
</td>
</tr>
<tr>
<td class="col-md-4">
<span class="modifier-icon icon ion-ios-reset"></span>
<code>intercept(context: ExecutionContext, next: CallHandler<any>)</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="45"
class="link-to-prism">src/core/interceptors/page.interceptor.ts:45</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Override of intercept() method, specified in NestInterceptor interface</p>
</div>
<div class="io-description">
<b>Parameters :</b>
<table class="params">
<thead>
<tr>
<td>Name</td>
<td>Type</td>
<td>Optional</td>
</tr>
</thead>
<tbody>
<tr>
<td>context</td>
<td>
<code>ExecutionContext</code>
</td>
<td>
No
</td>
</tr>
<tr>
<td>next</td>
<td>
<code>CallHandler<any></code>
</td>
<td>
No
</td>
</tr>
</tbody>
</table>
</div>
<div>
</div>
<div class="io-description">
<b>Returns : </b> <code><a href="../classes/PageDto.html" target="_self" >Promise<Observable<PageDto>></a></code>
</div>
<div class="io-description">
<p>Page with content and metadata</p>
</div>
</td>
</tr>
</tbody>
</table>
</section>
<section>
<h3 id="inputs">
Properties
</h3>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<a name="ES_IP"></a>
<span class="name">
<span class="modifier">Private</span>
<span class="modifier">Readonly</span>
<span ><b>ES_IP</b></span>
<a href="#ES_IP"><span class="icon ion-ios-link"></span></a>
</span>
</td>
</tr>
<tr>
<td class="col-md-4">
<i>Default value : </i><code>process.env.ES_CONTAINER_NAME</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="37" class="link-to-prism">src/core/interceptors/page.interceptor.ts:37</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Elastichsearch IP address</p>
</div>
</td>
</tr>
</tbody>
</table>
<table class="table table-sm table-bordered">
<tbody>
<tr>
<td class="col-md-4">
<a name="ES_PORT"></a>
<span class="name">
<span class="modifier">Private</span>
<span class="modifier">Readonly</span>
<span ><b>ES_PORT</b></span>
<a href="#ES_PORT"><span class="icon ion-ios-link"></span></a>
</span>
</td>
</tr>
<tr>
<td class="col-md-4">
<i>Default value : </i><code>process.env.ES_PORT</code>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-line">Defined in <a href="" data-line="32" class="link-to-prism">src/core/interceptors/page.interceptor.ts:32</a></div>
</td>
</tr>
<tr>
<td class="col-md-4">
<div class="io-description"><p>Elastichsearch server port-number</p>
</div>
</td>
</tr>
</tbody>
</table>
</section>
</div>
<div class="tab-pane fade tab-source-code" id="c-source">
<pre class="line-numbers compodoc-sourcecode"><code class="language-typescript">import { HttpService } from "@nestjs/axios";
import { CACHE_MANAGER, CallHandler, ExecutionContext, Inject, Injectable, NestInterceptor } from "@nestjs/common";
import { Observable, map, take, switchMap, of } from "rxjs";
import { PageDto } from "../domain/dtos";
import { EsQueryDto } from "../domain/dtos/elastic/es-query.dto";
import { RequestDto } from "../domain/dtos/request.dto";
import { SearchQueryDto } from "../domain/dtos/search-q.dto";
import { EsTime } from "../domain/enums/es-time.enum";
import { Order, toOrder } from "../domain/enums/page-order.enum";
import { EsPit } from "../domain/interfaces/elastic/es-pit.interface";
import { Cache } from 'cache-manager'
import { PageMetaDto } from "../domain/dtos/page-meta.dto";
/**
* Pagination-implementing interceptor
*/
@Injectable()
export class PageInterceptor implements NestInterceptor {
/**
* Injects needed dependencies and instantiates the storage object
* @param httpService
* @param searchService
*/
constructor(
private readonly httpService: HttpService,
@Inject(CACHE_MANAGER) private cacheManager: Cache
) {}
/**
* Elastichsearch server port-number
*/
private readonly ES_PORT = process.env.ES_PORT;
/**
* Elastichsearch IP address
*/
private readonly ES_IP = process.env.ES_CONTAINER_NAME;
/**
* Override of intercept() method, specified in NestInterceptor interface
* @param context
* @param next
* @returns Page with content and metadata
*/
async intercept(context: ExecutionContext, next: CallHandler<any>): Promise<Observable<PageDto>> {
const request: RequestDto = context.switchToHttp().getRequest<RequestDto>();
const query: SearchQueryDto = request.query;
const offset = !query.offset ? 0 : query.offset;
const limit = !query.limit ? 10 : query.limit;
const order = !query.order ? Order.DESC : query.order;
const prev_page = await this.cacheManager.get('prev_page');
if (prev_page) {
if (offset == prev_page[1] && limit == prev_page[2] && order == prev_page[3]) return of(prev_page[0]);
}
// Contruct a body for querying Elasticsearch
request.es_query = new EsQueryDto();
request.es_query.query = {
query_string: {
query: query.query,
default_field: 'content',
}
};
request.es_query.from = offset;
request.es_query.size = limit;
return next.handle().pipe(
switchMap(async (res) => {
// Setting the page meta-data
let meta: PageMetaDto = {
total: res.hits.total.value,
order: toOrder(order),
};
// Check if the performed search is a backwards search
let data = res.hits.hits;
// Omitting the redundant info and leaving only the document
data = data.map((el) => el._source);
// Change the order if set
if (order == Order.ASC) data.reverse();
// Cache and return the page
const page: PageDto = new PageDto(data, meta);
await this.cacheManager.set('prev_page', [page, offset, limit, order]);
return page;
})
);
}
/**
* Acquires a PIT ID from Elasticsearch, needed for a request
* @param alive, amount of time in minutes (defaults to 1). If time unit is not specified - defaults to minutes.
* @returns PIT object <EsPit> containing PIT ID and keep_alive value
*/
public async getPIT(alive: number, unit: EsTime = EsTime.min): Promise<EsPit> {
return new Promise((resolve, reject) => {
try {
this.httpService.post<EsPit>(`http://${this.ES_IP}:${this.ES_PORT}/papers/_pit?keep_alive=${alive+unit}`)
.pipe(take(1), map(axiosRes => axiosRes.data))
.subscribe((res: EsPit) => {
res.keep_alive = alive + unit;
resolve(res);
});
} catch (error) {
reject(error);
}
});
}
/**
* Deletes the PIT specified by provided ID
* @param pitID, ID of the PIT, that would be deleted
* @returns true/false, depending on the result of deletion of the PIT
*/
async deletePIT(pitID: string): Promise<boolean> {
return new Promise((resolve, reject) => {
try {
this.httpService.delete(`http://${this.ES_IP}:${this.ES_PORT}/_pit`, {
data: { id: pitID },
headers: { 'Content-Type': 'application/json' },
})
.pipe(take(1), map(axiosRes => axiosRes.data))
.subscribe((res) => {
resolve(res.succeeded);
});
} catch (error) {
reject(error);
}
})
}
}</code></pre>
</div>
</div>
</div><div class="search-results">
<div class="has-results">
<h1 class="search-results-title"><span class='search-results-count'></span> results matching "<span class='search-query'></span>"</h1>
<ul class="search-results-list"></ul>
</div>
<div class="no-results">
<h1 class="search-results-title">No results matching "<span class='search-query'></span>"</h1>
</div>
</div>
</div>
<!-- END CONTENT -->
</div>
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<input type="checkbox">
<span class="slider">
<svg class="slider-icon" viewBox="0 0 24 24" fill="none" height="20" stroke="#000" stroke-linecap="round" stroke-linejoin="round" stroke-width="2" width="20" xmlns="http://www.w3.org/2000/svg">
<path d="M21 12.79A9 9 0 1111.21 3 7 7 0 0021 12.79z"></path>
</svg>
</span>
</label>
<script>
var COMPODOC_CURRENT_PAGE_DEPTH = 1;
var COMPODOC_CURRENT_PAGE_CONTEXT = 'injectable';
var COMPODOC_CURRENT_PAGE_URL = 'PageInterceptor.html';
var MAX_SEARCH_RESULTS = 15;
</script>
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<script src="../js/search/search-lunr.js"></script>
<script src="../js/search/search_index.js"></script>
<script src="../js/lazy-load-graphs.js"></script>
</body>
</html>