82 lines
2.2 KiB
JavaScript
82 lines
2.2 KiB
JavaScript
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'use strict';
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const JSON2CSVBase = require('./JSON2CSVBase');
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const { fastJoin, flattenReducer } = require('./utils');
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class JSON2CSVParser extends JSON2CSVBase {
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constructor(opts) {
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super(opts);
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if (this.opts.fields) {
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this.opts.fields = this.preprocessFieldsInfo(this.opts.fields);
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}
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}
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/**
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* Main function that converts json to csv.
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*
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* @param {Array|Object} data Array of JSON objects to be converted to CSV
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* @returns {String} The CSV formated data as a string
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*/
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parse(data) {
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const processedData = this.preprocessData(data);
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if (!this.opts.fields) {
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this.opts.fields = processedData
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.reduce((fields, item) => {
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Object.keys(item).forEach((field) => {
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if (!fields.includes(field)) {
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fields.push(field)
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}
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});
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return fields
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}, []);
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this.opts.fields = this.preprocessFieldsInfo(this.opts.fields);
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}
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const header = this.opts.header ? this.getHeader() : '';
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const rows = this.processData(processedData);
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const csv = (this.opts.withBOM ? '\ufeff' : '')
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+ header
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+ ((header && rows) ? this.opts.eol : '')
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+ rows;
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return csv;
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}
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/**
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* Preprocess the data according to the give opts (unwind, flatten, etc.)
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and calculate the fields and field names if they are not provided.
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*
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* @param {Array|Object} data Array or object to be converted to CSV
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*/
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preprocessData(data) {
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const processedData = Array.isArray(data) ? data : [data];
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if (!this.opts.fields && (processedData.length === 0 || typeof processedData[0] !== 'object')) {
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throw new Error('Data should not be empty or the "fields" option should be included');
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}
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if (this.opts.transforms.length === 0) return processedData;
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return processedData
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.map(row => this.preprocessRow(row))
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.reduce(flattenReducer, []);
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}
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/**
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* Create the content row by row below the header
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*
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* @param {Array} data Array of JSON objects to be converted to CSV
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* @returns {String} CSV string (body)
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*/
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processData(data) {
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return fastJoin(
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data.map(row => this.processRow(row)).filter(row => row), // Filter empty rows
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this.opts.eol
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);
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}
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}
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module.exports = JSON2CSVParser;
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