和其他人一样，在我使用yql从网站获取数据之前。该网站为xml格式。
我这样做是为了在Tableau中构建一个Web数据连接器以连接到xml数据，我从这里获得了代码：https://github.com/tableau/webdataconnector/blob/v1.1.0/Examples/xmlConnector.html
按照此处的建议：YQL: html table is no longer supported我尝试了htmlstring并将引用添加到社区环境。
// try to use yql as a proxy
function _yqlProxyAjaxRequest2(url, successCallback){
var yqlQueryBase = "http://query.yahooapis.com/v1/public/yql?q=";
var query = "select * from htmlstring where url='" + url + "'";
var restOfQueryString = "&format=xml" ;
var yqlUrl = yqlQueryBase + encodeURIComponent(query) + restOfQueryString + "&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys";
_ajaxRequestHelper(url, successCallback, yqlUrl, _giveUpOnUrl9);
}
function _giveUpOnUrl9(url, successCallback) {
tableau.abortWithError("Could not load url: " + url);
}
但是，我仍然收到消息：不再支持HTML表。
由于我对yql不太了解，所以我尝试与xmlHttpRequest合作，但是Tableau最终处理了年龄的请求，但没有任何反应。
这是我尝试寻找其他解决方案并避免出现yql的麻烦：
function _retrieveXmlData(retrieveDataCallback) {
if (!window.cachedTableData) {
var conData = JSON.parse(tableau.connectionData);
var xmlString = conData.xmlString;
if (conData.xmlUrl) {
var successCallback = function(data) {
window.cachedTableData = _xmlToTable(data);
retrieveDataCallback(window.cachedTableData);
};
//INSTEAD OF THIS:
//_basicAjaxRequest1(conData.xmlUrl, successCallback);
//USE NOT YQL BUT XMLHTTPREQUEST:
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
myFunction(this);
}
};
xhttp.open('GET', 'https://www.w3schools.com/xml/cd_catalog.xml', true);
xhttp.send();
return;
}
try {
var xmlDoc = $.parseXML(conData.xmlString);
window.cachedTableData = _xmlToTable(xmlDoc);
}
catch (e) {
tableau.abortWithError("unable to parse xml data");
return;
}
}
retrieveDataCallback(window.cachedTableData);
}
有人知道如何让YQL工作或对我尝试避免的方法发表评论吗？
非常感谢您！
作为参考，如果有任何Tableau用户想要在Tableau上对其进行测试，这是我的完整代码：
<html>
<head>
<title>XML Connector</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js" type="text/javascript"></script>
<script src="https://connectors.tableau.com/libs/tableauwdc-1.1.1.js" type="text/javascript"></script>
<script type="text/javascript">
(function() {
var myConnector = tableau.makeConnector();
myConnector.init = function () {
tableau.connectionName = 'XML data';
tableau.initCallback();
};
myConnector.getColumnHeaders = function() {
_retrieveXmlData(function (tableData) {
var headers = tableData.headers;
var fieldNames = [];
var fieldTypes = [];
for (var fieldName in headers) {
if (headers.hasOwnProperty(fieldName)) {
fieldNames.push(fieldName);
fieldTypes.push(headers[fieldName]);
}
}
tableau.headersCallback(fieldNames, fieldTypes); // tell tableau about the fields and their types
});
}
myConnector.getTableData = function (lastRecordToken) {
_retrieveXmlData(function (tableData) {
var rowData = tableData.rowData;
tableau.dataCallback(rowData, rowData.length.toString(), false);
});
};
tableau.registerConnector(myConnector);
})();
function _retrieveXmlData(retrieveDataCallback) {
if (!window.cachedTableData) {
var conData = JSON.parse(tableau.connectionData);
var xmlString = conData.xmlString;
if (conData.xmlUrl) {
var successCallback = function(data) {
window.cachedTableData = _xmlToTable(data);
retrieveDataCallback(window.cachedTableData);
};
//_basicAjaxRequest1(conData.xmlUrl, successCallback);
//here try another approach not using yql but xmlHttpRequest?
//try xml dom to get url (xml http request)
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
myFunction(this);
}
};
xhttp.open('GET', 'https://www.w3schools.com/xml/cd_catalog.xml', true);
xhttp.send();
return;
}
try {
var xmlDoc = $.parseXML(conData.xmlString);
window.cachedTableData = _xmlToTable(xmlDoc);
}
catch (e) {
tableau.abortWithError("unable to parse xml data");
return;
}
}
retrieveDataCallback(window.cachedTableData);
}
function myFunction(xml) {
var xmlDoc = xml.responseXML;
window.cachedTableData = _xmlToTable(xmlDoc);
}
// There are a lot of ways to handle URLS. Sometimes we'll need workarounds for CORS. These
// methods chain together a series of attempts to get the data at the given url
function _ajaxRequestHelper(url, successCallback, conUrl, nextFunction,
specialSuccessCallback){
specialSuccessCallback = specialSuccessCallback || successCallback;
var xhr = $.ajax({
url: conUrl,
dataType: 'xml',
success: specialSuccessCallback,
error: function()
{
nextFunction(url, successCallback);
}
});
}
// try the straightforward request
function _basicAjaxRequest1(url, successCallback){
_ajaxRequestHelper(url, successCallback, url, _yqlProxyAjaxRequest2);
}
// try to use yql as a proxy
function _yqlProxyAjaxRequest2(url, successCallback){
var yqlQueryBase = "http://query.yahooapis.com/v1/public/yql?q=";
var query = "select * from htmlstring where url='" + url + "'";
var restOfQueryString = "&format=xml" ;
var yqlUrl = yqlQueryBase + encodeURIComponent(query) + restOfQueryString + "&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys";
_ajaxRequestHelper(url, successCallback, yqlUrl, _giveUpOnUrl9);
}
function _giveUpOnUrl9(url, successCallback) {
tableau.abortWithError("Could not load url: " + url);
}
// Takes a hierarchical xml document and tries to turn it into a table
// Returns an object with headers and the row level data
function _xmlToTable(xmlDocument) {
var rowData = _flattenData(xmlDocument);
var headers = _extractHeaders(rowData);
return {"headers":headers, "rowData":rowData};
}
// Given an object:
// - finds the longest array in the xml
// - flattens each element in that array so it is a single element with many properties
// If there is no array that is a descendent of the original object, this wraps
function _flattenData(xmlDocument) {
// first find the longest array
var longestArray = _findLongestArray(xmlDocument, xmlDocument);
if (!longestArray || longestArray.length == 0) {
// if no array found, just wrap the entire object blob in an array
longestArray = [objectBlob];
}
toRet = [];
for (var ii = 0; ii < longestArray.childNodes.length; ++ii) {
toRet[ii] = _flattenObject(longestArray.childNodes[ii]);
}
return toRet;
}
// Given an element with hierarchical properties, flattens it so all the properties
// sit on the base element.
function _flattenObject(xmlElt) {
var toRet = {};
if (xmlElt.attributes) {
for (var attributeNum = 0; attributeNum < xmlElt.attributes.length; ++attributeNum) {
var attribute = xmlElt.attributes[attributeNum];
toRet[attribute.nodeName] = attribute.nodeValue;
}
}
var children = xmlElt.childNodes;
if (!children || !children.length) {
if (xmlElt.textContent) {
toRet.text = xmlElt.textContent.trim();
}
} else {
for (var childNum = 0; childNum < children.length; ++childNum) {
var child = xmlElt.childNodes[childNum];
var childName = child.nodeName;
var subObj = _flattenObject(child);
for (var k in subObj) {
if (subObj.hasOwnProperty(k)) {
toRet[childName + '_' + k] = subObj[k];
}
}
}
}
return toRet;
}
// Finds the longest array that is a descendent of the given object
function _findLongestArray(xmlElement, bestSoFar) {
var children = xmlElement.childNodes;
if (children && children.length) {
if (children.length > bestSoFar.childNodes.length) {
bestSoFar = xmlElement;
}
for (var childNum in children) {
var subBest = _findLongestArray(children[childNum], bestSoFar);
if (subBest.childNodes.length > bestSoFar.childNodes.length) {
bestSoFar = subBest;
}
}
}
return bestSoFar;
}
// Given an array of js objects, returns a map from data column name to data type
function _extractHeaders(rowData) {
var toRet = {};
for (var row = 0; row < rowData.length; ++row) {
var rowLine = rowData[row];
for (var key in rowLine) {
if (rowLine.hasOwnProperty(key)) {
if (!(key in toRet)) {
toRet[key] = _determineType(rowLine[key]);
}
}
}
}
return toRet;
}
// Given a primitive, tries to make a guess at the data type of the input
function _determineType(primitive) {
// possible types: 'float', 'date', 'datetime', 'bool', 'string', 'int'
if (parseInt(primitive) == primitive) return 'int';
if (parseFloat(primitive) == primitive) return 'float';
if (isFinite(new Date(primitive).getTime())) return 'datetime';
return 'string';
}
function _submitXMLToTableau(xmlString, xmlUrl) {
var conData = {"xmlString" : xmlString, "xmlUrl": xmlUrl};
tableau.connectionData = JSON.stringify(conData);
tableau.submit();
}
function _buildConnectionUrl(url) {
// var yqlQueryBase = "http://query.yahooapis.com/v1/public/yql?q=";
// var query = "select * from html where url='" + url + "'";
// var restOfQueryString = "&format=xml";
// var yqlUrl = yqlQueryBase + encodeURIComponent(query) + restOfQueryString;
// return yqlUrl;
return url;
}
$(document).ready(function(){
var cancel = function (e) {
e.stopPropagation();
e.preventDefault();
}
$("#inputForm").submit(function(e) { // This event fires when a button is clicked
// Since we use a form for input, make sure to stop the default form behavior
cancel(e);
var xmlString = $('textarea[name=xmlText]')[0].value.trim();
var xmlUrl = $('input[name=xmlUrl]')[0].value.trim();
_submitXMLToTableau(xmlString, xmlUrl);
});
var ddHandler = $("#dragandrophandler");
ddHandler.on('dragenter', function (e)
{
cancel(e);
$(this).css('border', '2px solid #0B85A1');
}).on('dragover', cancel)
.on('drop', function (e)
{
$(this).css('border', '2px dashed #0B85A1');
e.preventDefault();
var files = e.originalEvent.dataTransfer.files;
var file = files[0];
var reader = new FileReader();
reader.onload = function(e) { _submitXMLToTableau(reader.result); };
reader.readAsText(file);
});
$(document).on('dragenter', cancel)
.on('drop', cancel)
.on('dragover', function (e)
{
cancel(e);
ddHandler.css('border', '2px dashed #0B85A1');
});
});
</script>
<style>
#dragandrophandler {
border:1px dashed #999;
width:300px;
color:#333;
text-align:left;vertical-align:middle;
padding:10px 10px 10 10px;
margin:10px;
font-size:150%;
}
</style>
</head>
<body>
<form id="inputForm" action="">
Enter a URL for XML data:
<input type="text" name="xmlUrl" size="50" />
<br>
<div id="dragandrophandler">Or Drag & Drop Files Here</div>
<br>
Or paste XML data below
<br>
<textarea name="xmlText" rows="10" cols="70"/></textarea>
<input type="submit" value="Submit">
</form>