如何使用U-SQL 中的XML 提取器从 XML 元素中提取属性值以用于我的 Azure 数据湖分析作业。
更新:有关该问题的更多详细信息
我的 XML 文件如下所示:
<?xml version="1.0" encoding="utf-8"?>
<testelement testatr="xyz">
</testelement>
这是我的 U-SQL 脚本:
DECLARE @testfile string = "sample2.xml";
@logText =
EXTRACT log string
FROM @testfile
USING Extractors.Tsv();
@gethID = SELECT Microsoft.Analytics.Samples.Formats.Xml.XPath.Evaluate(@logText.log, "testelement/attribute::testatr").ElementAt(0) AS siteName FROM @logText;
OUTPUT @gethID TO "result.out" USING Outputters.Tsv();
调试后观察,XPath类的Load方法尝试加载时出现异常:
"<?xml version=1.0 encoding=utf-8?>"
这是一个例外:
Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.ScopeDebugException was unhandled
Message: An unhandled exception of type 'Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.ScopeDebugException' occurred in Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.dll
Additional information: {"diagnosticCode":195887111,"severity":"Error","component":"RUNTIME","source":"User","errorId":"E_RUNTIME_USER_EXPRESSIONEVALUATION","message":"Error while evaluating expression Microsoft.Analytics.Samples.Formats.Xml.XPath.Evaluate(log, \"testelement/attribute::testatr\").ElementAt(0)","description":"Inner exception from user expression: '1.0' is an unexpected token. The expected token is '\"' or '''. Line 1, position 15.\nCurrent row dump: \tlog:\t\"<?xml version=1.0 encoding=utf-8?>\"
\n","resolution":"","helpLink":"","details":"==== Caught exception System.Xml.XmlException\n\n at System.Xml.XmlTextReaderImpl.Throw(Exception e)
\n at System.Xml.XmlTextReaderImpl.ParseXmlDeclaration(Boolean isTextDecl)
\n at System.Xml.XmlTextReaderImpl.Read()
\n at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
\n at System.Xml.XmlDocument.Load(XmlReader reader)
\n at System.Xml.XmlDocument.LoadXml(String xml)
\n at Microsoft.Analytics.Samples.Formats.Xml.XPath.Load(String xml)
\n at Microsoft.Analytics.Samples.Formats.Xml.XPath.Evaluate(String xml, String xpath)
\n at ___Scope_Generated_Classes___.SqlFilterTransformer_2.Process(IRow row, IUpdatableRow output) in c:\\workarea\\bswbigdata\\USQLAppForLogs\\USQLAppForLogs\\bin\\Debug\\A06D46624BBA798\\ReadBlobs.usql.Debug_A54F30D359F939C7\\__ScopeCodeGen__.dll.cs:line 53","internalDiagnostics":""}
更新 2:
使用 quoting:false 后,我得到另一个异常:
Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.ScopeDebugException was unhandled
Message: An unhandled exception of type 'Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.ScopeDebugException' occurred in Microsoft.Cosmos.ScopeStudio.BusinessObjects.Debugger.dll
Additional information: {"diagnosticCode":195887111,"severity":"Error","component":"RUNTIME","source":"User","errorId":"E_RUNTIME_USER_EXPRESSIONEVALUATION","message":"Error while evaluating expression Microsoft.Analytics.Samples.Formats.Xml.XPath.Evaluate(log, \"testelement/attribute::testatr\").ElementAt(0)","description":"Inner exception from user expression: Root element is missing.\nCurrent row dump: \tlog:\t\"<?xml version=\"1.0\" encoding=\"utf-8\"?>\"
\n","resolution":"","helpLink":"","details":"==== Caught exception System.Xml.XmlException\n\n at System.Xml.XmlTextReaderImpl.Throw(Exception e)
\n at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
\n at System.Xml.XmlLoader.LoadDocSequence(XmlDocument parentDoc)
\n at System.Xml.XmlDocument.Load(XmlReader reader)
\n at System.Xml.XmlDocument.LoadXml(String xml)
\n at Microsoft.Analytics.Samples.Formats.Xml.XPath.Load(String xml)
\n at Microsoft.Analytics.Samples.Formats.Xml.XPath.Evaluate(String xml, String xpath)
\n at ___Scope_Generated_Classes___.SqlFilterTransformer_2.Process(IRow row, IUpdatableRow output) in c:\\workarea\\bswbigdata\\USQLAppForLogs\\USQLAppForLogs\\bin\\Debug\\A06D46624BBA798\\ReadBlobs.usql.Debug_A54F30D359F939C7\\__ScopeCodeGen__.dll.cs:line 53","internalDiagnostics":""}