64 lines
2.6 KiB
JavaScript
64 lines
2.6 KiB
JavaScript
import { TextLoader } from "langchain/document_loaders/fs/text";
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/**
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* A class that extends the TextLoader class. It represents a document
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* loader that loads documents from a CSV file. It has a constructor that
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* takes a `filePathOrBlob` parameter representing the path to the CSV
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* file or a Blob object, and an optional `options` parameter of type
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* `CSVLoaderOptions` or a string representing the column to use as the
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* document's pageContent.
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*/
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export class CSVLoader extends TextLoader {
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constructor(filePathOrBlob, options) {
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super(filePathOrBlob);
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Object.defineProperty(this, "options", {
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enumerable: true,
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configurable: true,
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writable: true,
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value: {}
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});
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if (typeof options === "string") {
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this.options = { column: options };
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}
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else {
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this.options = options ?? this.options;
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}
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}
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/**
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* A protected method that parses the raw CSV data and returns an array of
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* strings representing the pageContent of each document. It uses the
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* `dsvFormat` function from the `d3-dsv` module to parse the CSV data. If
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* the `column` option is specified, it checks if the column exists in the
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* CSV file and returns the values of that column as the pageContent. If
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* the `column` option is not specified, it converts each row of the CSV
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* data into key/value pairs and joins them with newline characters.
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* @param raw The raw CSV data to be parsed.
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* @returns An array of strings representing the pageContent of each document.
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*/
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async parse(raw) {
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const { column, separator = "," } = this.options;
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const { dsvFormat } = await CSVLoaderImports();
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const psv = dsvFormat(separator);
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const parsed = psv.parse(raw.trim());
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if (column !== undefined) {
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if (!parsed.columns.includes(column)) {
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throw new Error(`Column ${column} not found in CSV file.`);
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}
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// Note TextLoader will raise an exception if the value is null.
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// eslint-disable-next-line @typescript-eslint/no-non-null-assertion
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return parsed.map((row) => row[column]);
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}
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return parsed.map((row) => Object.keys(row)
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.map((key) => `${key.trim()}: ${row[key]?.trim()}`)
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.join("\n"));
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}
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}
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async function CSVLoaderImports() {
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try {
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const { dsvFormat } = await import("d3-dsv");
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return { dsvFormat };
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}
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catch (e) {
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console.error(e);
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throw new Error("Please install d3-dsv as a dependency with, e.g. `yarn add d3-dsv@2`");
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}
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}
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