79 lines
3.1 KiB
JavaScript
79 lines
3.1 KiB
JavaScript
import { Document } from "@langchain/core/documents";
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import { CheerioWebBaseLoader } from "./cheerio.js";
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/**
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* A class that extends the CheerioWebBaseLoader class. It represents a
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* loader for loading web pages from the Hacker News website.
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*/
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export class HNLoader extends CheerioWebBaseLoader {
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constructor(webPath) {
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super(webPath);
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Object.defineProperty(this, "webPath", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: webPath
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});
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}
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/**
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* An asynchronous method that loads the web page. If the webPath includes
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* "item", it calls the loadComments() method to load the comments from
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* the web page. Otherwise, it calls the loadResults() method to load the
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* results from the web page.
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* @returns A Promise that resolves to an array of Document instances.
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*/
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async load() {
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const $ = await this.scrape();
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if (this.webPath.includes("item")) {
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return this.loadComments($);
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}
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return this.loadResults($);
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}
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/**
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* A private method that loads the comments from the web page. It selects
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* the elements with the class "athing comtr" using the $ function
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* provided by Cheerio. It also extracts the title of the web page from
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* the element with the id "pagespace". It creates Document instances for
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* each comment, with the comment text as the page content and the source
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* and title as metadata.
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* @param $ A CheerioAPI instance.
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* @returns An array of Document instances.
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*/
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loadComments($) {
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const comments = $("tr[class='athing comtr']");
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const title = $("tr[id='pagespace']").attr("title");
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const documents = [];
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comments.each((_index, comment) => {
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const text = $(comment).text().trim();
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const metadata = { source: this.webPath, title };
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documents.push(new Document({ pageContent: text, metadata }));
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});
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return documents;
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}
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/**
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* A private method that loads the results from the web page. It selects
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* the elements with the class "athing" using the $ function provided by
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* Cheerio. It extracts the ranking, link, title, and other metadata from
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* each result item. It creates Document instances for each result item,
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* with the title as the page content and the source, title, link, and
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* ranking as metadata.
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* @param $ A CheerioAPI instance.
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* @returns An array of Document instances.
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*/
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loadResults($) {
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const items = $("tr[class='athing']");
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const documents = [];
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items.each((_index, item) => {
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const ranking = $(item).find("span[class='rank']").text();
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const link = $(item).find("span[class='titleline'] a").attr("href");
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const title = $(item).find("span[class='titleline']").text().trim();
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const metadata = {
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source: this.webPath,
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title,
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link,
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ranking,
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};
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documents.push(new Document({ pageContent: title, metadata }));
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});
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return documents;
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}
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}
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