使用 textract 模块抓取 PDF

Question

我有一个 Node.js 应用程序，它必须对在线 pdf 进行一些网络抓取。这是一段代码：

var textract = require('textract');
const util = require('util');

var methods = {};

var urls = [
    {year: '2016', link: 'http://www.url2016.pdf'},
    {year: '2015', link: 'http://www.url2015.pdf'}
];
var result = [];

const textractFromUrl = util.promisify(textract.fromUrl);


methods.download = function(req, res) {
    return extractText();
}

async function extractText() {
    try {
        var config = {
            preserveLineBreaks: true
        };
        for(let url of urls) {
            let text = await textractFromUrl(url.link, config);
            switch(url.year) {
                case '2015':
                    await extractTextType1(url, text);
                    break;

                case '2016':
                    await extractTextType2(url, text);
                    break;

                default:
                    console.log('Error: no switch case');
            }
        }
    }
    catch(err) {
        console.log('catch block');
        console.log(err);
    }
}

如您所见，我使用 textrack 包来抓取 pdf。当我运行这个应用程序时，我得到：

catch block
{ Error: Error for type: [[ application/pdf ]], file: [[ C:\Users\myUserName\AppData\Local\Temp710848773.pdf ]], extractor for type exists, but failed to initialize. Message: INFO: 'pdftotext' does not appear to be installed, so textract will be unable to extract PDFs.
    at extract (C:\Users\myUserName\projectPath\node_modules\textract\lib\extract.js:147:15)
    at Timeout._onTimeout (C:\Users\myUserName\projectPath\node_modules\textract\lib\extract.js:155:7)
    at ontimeout (timers.js:466:11)
    at tryOnTimeout (timers.js:304:5)
    at Timer.listOnTimeout (timers.js:267:5) typeNotFound: true }

在npm textract module page, is written that PDF extraction requires pdftotext be installed, link.

所以我去 http://www.foolabs.com/xpdf/download.html 下载并安装 下载 XpdfReader：Windows 64 位.

我再次尝试运行使用 node app.js 的应用程序（app.js 是我的应用程序的主文件）但我遇到了同样的错误所以我下载了 下载 Xpdf 工具：Windows 64 位。

这是一个 zip 文件，我解压了该文件，然后尝试安装 pdftotext.exe，但是当我双击 pdftotext.exe 时，什么都发生了。我也尝试使用管理员权限安装它。没有。

我正在使用 Windows 10、64 位。

我必须做什么？

编辑 1

按照建议，我将 pdftotext.exe 文件复制到 C:\Windows\System32。然后我又运行我的程序，我遇到了这个问题：

catch block
TypeError: Cannot read property 'split' of undefined
    at extractTextType4 (C:\myUserName\projectPath\file.js:301:28)
    at extractText (C:\myUserName\projectPath\file.js:78:12)
    at <anonymous>
    at process._tickCallback (internal/process/next_tick.js:182:7)

我必须更改环境变量吗？

编辑 2

我的C:\myUserName\projectPath\file.js是这样的：

var textract = require('textract');
const util = require('util');
var utilFunc = require('../helpers/utilFunc.js'); // my lib
var postgreSQLlib = require('../middlewares/postgreSQLlib.js'); // my lib

// object of methods
var methods = {};

// object of pdf links
var urls = [
    {year: '2014', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_0_fileAllegati_itemFile_2_file.pdf'}, 
    {year: '2013', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_0_fileAllegati_itemFile_1_file.pdf'}, 
    {year: '2012', link: 'http://www.salute.gov.it/imgs/C_17_tavole_20_allegati_iitemAllegati_5_fileAllegati_itemFile_0_file.pdf'}
];
var result = [];

const textractFromUrl = util.promisify(textract.fromUrl);

/**
 * Do web scraping and save info on DB.
 */
methods.download = function(req, res) {
    return extractText();
}

/**
 * Switch between different type of pdf file.
 */
async function extractText() {
    try {
        var config = {
            preserveLineBreaks: true
        };
        for(let url of urls) {
            let text = await textractFromUrl(url.link, config);
            switch(url.year) {
                case '2012':
                    await extractTextType1(url, text);
                    break;

                case '2013': 
                    await extractTextType2(url, text);
                    break;

                case '2014': 
                    await extractTextType3(url, text);
                    break;

                default:
                    console.log('Error: no switch case');
            }
        }
    }
    catch(err) {
        console.log('catch block');
        console.log(err);
    }
}

/**
 * Save data on DB.
 */
function saveOnObject(vaccines, regions, map, url) {
    vaccines = map.shift(); // remove and return the first element 
    regions = map.shift(); // remove and return the first element 

    let promises = [];
    for(var i = 0; i <= 21; i++) {
        var line = map[i]; 
        line.forEach(async function(value, index) { 

            // make the values uniform
            var vac = utilFunc.makeUniform(vaccines[index], 'vaccine');
            var reg = utilFunc.makeUniform(regions[i], 'region');
            var perc = utilFunc.makeUniform(value, 'value');

            // create json object
            var obj = utilFunc.createJsonObjectCov(parseFloat(url.year), 'Italy', vac, reg, perc);
            covDataItAll.push(obj);
        });
    }
    return Promise.all(promises);
}

/**
 * Extract text to pdf 2000-2012.
 */
function extractTextType1(url, text) {
    var matrix = [];
    var map = [];
    var vaccines = [];
    var regionsTemp = [];
    var regions = [];
    var regionLength = [1, 2, 1, 2, 3, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1]; 

    // text to matrix
    var textArray = text.split('\n');
    for(var i = 0; i < 23; i++) {
        matrix[i] = textArray[i].split(' ');
    }

    // create vaccines array
    matrix[0].shift();
    vaccines = matrix[0];
    map[0] = vaccines;

    // create regionsTemp and values arrays 
    for(var i = 0; i < regionLength.length; i++) { // i index for regionLength
        var j = i + 1; // index for matrix
        var indexToRemove = 0;
        var numberToRemove = regionLength[i];
        var region = matrix[j].splice(indexToRemove, numberToRemove);
        regionsTemp.push(region);
        map[j+1] = matrix[j];
    }

    // create regions array (merge some elements)
    for(var i = 0; i < regionsTemp.length; i++) {
        var region = '';
        if(regionLength[i] > 1) {
            region = regionsTemp[i].join(' ');
        }
        else {
            region = regionsTemp[i].join('');
        }
        regions.push(region);
    }
    map[1] = regions;

    // remove \r char from map
    for(var i = 0; i < map.length; i++) {
        for(var j = 0; j < map[i].length; j++) {
            map[i][j] = map[i][j].replace(/\r/g, '');
        }
    }

    return saveOnObject(vaccines, regions, map, url);
}

/**
 * Extract text to pdf 2013.
 */
function extractTextType2(url, text) {
    var matrix = [];
    var map = [];
    var vaccines = [];
    var regions = [];

    // text to matrix
    var textArray = text.split('\n');
    for(var i = 0; i < 36; i++) {
        matrix[i] = textArray[i].split(' ');
    }

    // create vaccines array
    vaccines.push(matrix[0][1].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    for(var i = 1; i < 10; i++) {
        vaccines.push(matrix[i][0].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    }
    var meningo = ''.concat(matrix[10][0], matrix[11]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.push(meningo);
    var pneumo = ''.concat(matrix[12][0], ' ', matrix[13]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.push(pneumo);
    map[0] = vaccines;

    // create regions array
    for(var i = 14; i < matrix.length; i++) { 
        regions.push(matrix[i][0]);
    }
    map[1] = regions;

    // create values array
    for(var i = 14; i < matrix.length; i++) {
        matrix[i].shift();
        map.push(matrix[i]);
    }

    // remove \r char from map
    for(var i = 0; i < map.length; i++) {
        for(var j = 0; j < map[i].length; j++) {
            map[i][j] = map[i][j].replace(/\r/g, '');
        }
    }

    return saveOnObject(vaccines, regions, map, url);
}

/**
 * Extract text to pdf 2014.
 */
function extractTextType3(url, text) {
    var matrix = [];
    var map = [];
    var vaccines = [];
    var regionsTemp = [];
    var regions = [];
    var regionLength = [1, 2, 1, 3, 3, 1, 3, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2]; // array that contains the length of the regions (I need to correctly split the arrays)

    // text to matrix
    var textArray = text.split('\n');

    for(var i = 0; i < 36; i++) {
        matrix[i] = textArray[i].split(' ');
    }

    // create vaccines array
    vaccines.push(matrix[0][2].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    for(var i = 1; i < 10; i++) {
        vaccines.push(matrix[i][0].replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, ''));
    }
    var meningo = ''.concat(matrix[10][0], ' ', matrix[10][1], ' ', matrix[11]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.push(meningo);
    var pneumo = ''.concat(matrix[12][0], ' ', matrix[13]).replace(/\(a\)/g, '').replace(/\(b\)/g, '').replace(/\(c\)/g, '').replace(/\r/g, '');
    vaccines.push(pneumo);
    map[0] = vaccines;

    // create regionsTemp and values arrays 
    for(var i = 0; i < regionLength.length; i++) { // i index for regionLength
        var j = i + 14; // index for matrix
        var indexToRemove = 0;
        var numberToRemove = regionLength[i];
        var region = matrix[j].splice(indexToRemove, numberToRemove);
        regionsTemp.push(region);
        map[i+2] = matrix[j];
    }

    // create regions array (merge some elements)
    for(var i = 0; i < regionsTemp.length; i++) {
        var region = '';
        if(regionLength[i] > 1) {
            region = regionsTemp[i].join(' ');
        }
        else {
            region = regionsTemp[i].join('');
        }
        regions.push(region);
    }
    map[1] = regions;

    // remove \r char from map
    for(var i = 0; i < map.length; i++) {
        for(var j = 0; j < map[i].length; j++) {
            map[i][j] = map[i][j].replace(/\r/g, '');
        }
    }

    return saveOnObject(vaccines, regions, map, url);
}

// exports methods
module.exports = methods;

Answer 1

将文件复制到 pdftotext.exe 到 c:\windows 或 c:\windows\system32。

基本上是添加到您的 PATH 中的任何文件夹。然后它应该工作

源码里可以看到

https://github.com/dbashford/textract/blob/078b3654b2f4e4f11a179714bd827a556fc1f64f/lib/extractors/pdf.js#L24

代码假定 pdftotext 在路径

中

使用 textract 模块抓取 PDF

PDF scraping using textract module

web-scraping

text-extraction

pdftotext

pdf-scraping

编辑 1

编辑 2