Error on line 1: Content is not allowed in prolog

问题:

I am trying to scrape a table of price data from this website using the following code;

function scrapeData() {
// Retrieve table as a string using Parser.
var url = "https://stooq.com/q/d/?s=barc.uk&i=d";

var fromText = '<td align="center" id="t03">';
var toText = '</td>';
var content = UrlFetchApp.fetch(url).getContentText();
var scraped = Parser.data(content).from(fromText).to(toText).build();

//Parse table using XmlService.
var root = XmlService.parse(scraped).getRootElement();
}

I have taken this method from an approach I used in a similar question here however its failing on this particular url and giving me the error;

Error on line 1: Content is not allowed in prolog. (line 12, file "Stooq")

In related questions here and here they talk of textual content that is not accepted being submitted to the parser however, I am unable to apply the solutions in these questions to my own problem. Any help would be much appreciated.

回答1:

How about this modification?

Modification points:

• In this case, it is required to modify the retrieved HTML values. For example, when var content = UrlFetchApp.fetch(url).getContentText() is run, each attribute value is not enclosed. These are required to be modified.
• There is a merged column in the header.

When above points are reflected to the script, it becomes as follows.

Modified script:

function scrapeData() {
  // Retrieve table as a string using Parser.
  var url = "https://stooq.com/q/d/?s=barc.uk&i=d";
  var fromText = '#d9d9d9}</style>';
  var toText = '<table';
  var content = UrlFetchApp.fetch(url).getContentText();
  var scraped = Parser.data(content).from(fromText).to(toText).build();

  // Modify values
  scraped = scraped.replace(/=([a-zA-Z0-9\%-:]+)/g, "=\"$1\"").replace(/nowrap/g, "");

  // Parse table using XmlService.
  var root = XmlService.parse(scraped).getRootElement();

  // Retrieve header and modify it.
  var headerTr = root.getChild("thead").getChildren();
  var res = headerTr.map(function(e) {return e.getChildren().map(function(f) {return f.getValue()})});
  res[0].splice(7, 0, "Change");

  // Retrieve values.
  var valuesTr = root.getChild("tbody").getChildren();
  var values = valuesTr.map(function(e) {return e.getChildren().map(function(f) {return f.getValue()})});
  Array.prototype.push.apply(res, values);

  // Put the result to the active spreadsheet.
  var ss = SpreadsheetApp.getActiveSheet();
  ss.getRange(1, 1, res.length, res[0].length).setValues(res);
}

Note:

• Before you run this modified script, please install the GAS library of Parser.
• This modified script is not corresponding to various URL. This can be used for the URL in your question. If you want to retrieve values from other URL, please modify the script.

Reference:

• Parser
• XmlService

If this was not what you want, I'm sorry.