com.trolltech.qt.xmlpatterns
Class QXmlQuery

java.lang.Object
  extended by com.trolltech.qt.internal.QSignalEmitterInternal
      extended by com.trolltech.qt.QSignalEmitter
          extended by com.trolltech.qt.QtJambiObject
              extended by com.trolltech.qt.xmlpatterns.QXmlQuery
All Implemented Interfaces:
QtJambiInterface

public class QXmlQuery
extends QtJambiObject

The QXmlQuery class performs XQueries on XML data, or on non-XML data modeled to look like XML. The QXmlQuery class compiles and executes queries written in the XQuery language. QXmlQuery is typically used to query XML data, but it can also query non-XML data that has been modeled to look like XML.

Using QXmlQuery to query XML data, as in the snippet below, is simple because it can use the built-in XML data model as its delegate to the underlying query engine for traversing the data. The built-in data model is specified in XQuery 1.0 and XPath 2.0 Data Model.

  QXmlQuery query = new QXmlQuery();
  query.setQuery("doc('index.html')/html/body/p[1]");

  QXmlSerializerPointer serializer(new QXmlSerializer(query, myOutputDevice));
  query.evaluateToReceiver(serializer);
The example uses QXmlQuery to match the first paragraph of an XML document and then output the result to a device as XML.

Using QXmlQuery to query non-XML data requires writing a subclass of QAbstractXmlNodeModel to use as a replacement for the built-in XML data model. The custom data model will be able to traverse the non-XML data as required by the QAbstractXmlNodeModel interface. An instance of this custom data model then becomes the delegate used by the query engine to traverse the non-XML data. For an example of how to use QXmlQuery to query non-XML data, see the documentation for QAbstractXmlNodeModel.

Running XQueries

To run a query set up with QXmlQuery, call one of the evaluation functions.

Running XPath Expressions

The XPath language is a subset of the XQuery language, so running an XPath expression is the same as running an XQuery query. Pass the XPath expression to QXmlQuery using
setQuery().

Running XSLT stylesheets

Running an XSLT stylesheet is like running an XQuery, except that when you construct your QXmlQuery, you must pass
QXmlQuery::XSLT20 to tell QXmlQuery to interpret whatever it gets from setQuery() as an XSLT stylesheet instead of as an XQuery. You must also set the input document by calling setFocus().Error parsing snippet. Note: Currently, setFocus() must be called beforesetQuery() when using XSLT.

Another way to run an XSLT stylesheet is to use the xmlpatterns command line utility.

xmlpatterns myStylesheet.xsl myInput.xml
Note: For the current release, XSLT support should be considered experimental. See section XSLT conformance for details.

Stylesheet parameters are bound using bindVariable().

Binding A Query To A Starting Node

When a query is run on XML data, as in the snippet above, the doc() function returns the node in the built-in data model where the query evaluation will begin. But when a query is run on a custom node model containing non-XML data, one of the bindVariable() functions must be called to bind a variable name to a starting node in the custom model. A $variable reference is used in the XQuery text to access the starting node in the custom model. It is not necessary to declare the variable name external in the query. See the example in the documentation for QAbstractXmlNodeModel.

Reentrancy and Thread-Safety

QXmlQuery is reentrant but not thread-safe. It is safe to use the QxmlQuery copy constructor to create a copy of a query and run the same query multiple times. Behind the scenes, QXmlQuery will reuse resources such as opened files and compiled queries to the extent possible. But it is not safe to use the same instance of QXmlQuery in multiple threads.

Error Handling

Errors can occur during query evaluation. Examples include type errors and file loading errors. When an error occurs:

Resource Management

When a query runs, it parses documents, allocating internal data structures to hold them, and it may load other resources over the network. It reuses these allocated resources when possible, to avoid having to reload and reparse them.

When setQuery() is called, the query text is compiled into an internal data structure and optimized. The optimized form can then be reused for multiple evaluations of the query. Since the compile-and-optimize process can be expensive, repeating it for the same query should be avoided by using a separate instance of QXmlQuery for each query text.

Once a document has been parsed, its internal representation is maintained in the QXmlQuery instance and shared among multiple QXmlQuery instances.

An instance of QCoreApplication must exist before QXmlQuery can be used.

Event Handling

When QXmlQuery accesses resources (e.g., calling fn:doc() to load a file, or accessing a device via a bound variable), the event loop is used, which means events will be processed. To avoid processing events when QXmlQuery accesses resources, create your QXmlQuery instance in a separate thread.


Nested Class Summary
static class QXmlQuery.QueryLanguage
          Specifies whether you want QXmlQuery to interpret the input to setQuery() as an XQuery or as an XSLT stylesheet.
 
Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
QSignalEmitter.AbstractSignal, QSignalEmitter.PrivateSignal0, QSignalEmitter.PrivateSignal1, QSignalEmitter.PrivateSignal2, QSignalEmitter.PrivateSignal3, QSignalEmitter.PrivateSignal4, QSignalEmitter.PrivateSignal5, QSignalEmitter.PrivateSignal6, QSignalEmitter.PrivateSignal7, QSignalEmitter.PrivateSignal8, QSignalEmitter.PrivateSignal9, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9
 
Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal
 
Field Summary
 
Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
currentSender
 
Constructor Summary
QXmlQuery()
          Constructs an invalid, empty query that cannot be used until setQuery() is called.
QXmlQuery(QXmlNamePool np)
          Constructs a query that will use np as its name pool.
QXmlQuery(QXmlQuery.QueryLanguage queryLanguage)
          Constructs a query that will be used to run Xqueries or XSL-T stylesheets, depending on the value of queryLanguage.
QXmlQuery(QXmlQuery.QueryLanguage queryLanguage, QXmlNamePool np)
          Constructs a query that will be used to run Xqueries or XSL-T stylesheets, depending on the value of queryLanguage.
QXmlQuery(QXmlQuery other)
          Constructs a QXmlQuery that is a copy of other.
 
Method Summary
 void bindVariable(QXmlName name, QIODevice arg__2)
          Binds the variable name to the device so that $name can be used from within the query to refer to the device.
 void bindVariable(QXmlName name, QXmlItem value)
          Binds the variable name to the value so that $name can be used from within the query to refer to the value.
 void bindVariable(QXmlName name, QXmlQuery query)
          Binds the result of the query query, to a variable by name name.
 void bindVariable(java.lang.String localName, QIODevice arg__2)
          This is an overloaded member function, provided for convenience.
 void bindVariable(java.lang.String localName, QXmlItem value)
          This is an overloaded member function, provided for convenience.
 void bindVariable(java.lang.String localName, QXmlQuery query)
          This is an overloaded member function, provided for convenience.
 java.lang.String evaluateTo()
          This is an overloaded method provided for convenience.
 boolean evaluateTo(QIODevice target)
          Evaluates the query or stylesheet, and writes the output to target.
 void evaluateTo(QXmlResultItems result)
          Starts the evaluation and makes it available in result.
 QXmlName initialTemplateName()
          Returns the name of the XSL-T stylesheet template that the processor will call first when running an XSL-T stylesheet.
 boolean isValid()
          Returns true if this query is valid.
 QAbstractMessageHandler messageHandler()
          Returns the message handler that handles compile and runtime messages for this QXmlQuery.
 QXmlNamePool namePool()
          Returns the name pool used by this QXmlQuery for constructing names.
 QNetworkAccessManager networkAccessManager()
          Returns the network manager, or 0 if it has not been set.
 QXmlQuery operator_assign(QXmlQuery other)
          Assigns other to this QXmlQuery instance.
 QXmlQuery.QueryLanguage queryLanguage()
          Returns a value indicating what this QXmlQuery is being used for.
 boolean setFocus(QIODevice document)
          Sets the focus to be the document read from the QIODevice and returns true.
 boolean setFocus(QUrl documentURI)
          This is an overloaded member function, provided for convenience.
 void setFocus(QXmlItem item)
          Sets the focus to item.
 void setInitialTemplateName(QXmlName name)
          Sets the name of the initial template.
 void setInitialTemplateName(java.lang.String name)
          This is an overloaded member function, provided for convenience.
 void setMessageHandler(QAbstractMessageHandler messageHandler)
          Changes the message handler for this QXmlQuery to aMessageHandler.
 void setNetworkAccessManager(QNetworkAccessManager newManager)
          Sets the network manager to newManager.
 void setQuery(QIODevice sourceCode)
          Sets this QXmlQuery to an XQuery read from the sourceCode device.
 void setQuery(QIODevice sourceCode, QUrl documentURI)
          Sets this QXmlQuery to an XQuery read from the sourceCode device.
 void setQuery(QUrl queryURI)
          Sets this QXmlQuery to the XQuery read from the queryURI.
 void setQuery(QUrl queryURI, QUrl baseURI)
          Sets this QXmlQuery to the XQuery read from the queryURI.
 void setQuery(java.lang.String sourceCode)
          This is an overloaded member function, provided for convenience.
 void setQuery(java.lang.String sourceCode, QUrl documentURI)
          This is an overloaded member function, provided for convenience.
 void setUriResolver(QAbstractUriResolver resolver)
          Sets the URI resolver to resolver.
 QAbstractUriResolver uriResolver()
          Returns the query's URI resolver.
 
Methods inherited from class com.trolltech.qt.QtJambiObject
dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr
 
Methods inherited from class com.trolltech.qt.QSignalEmitter
blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread
 
Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
__qt_signalInitialization
 
Methods inherited from class java.lang.Object
clone, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface com.trolltech.qt.QtJambiInterface
disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership
 

Constructor Detail

QXmlQuery

public QXmlQuery()
Constructs an invalid, empty query that cannot be used until setQuery() is called.

Note: This constructor must not be used if you intend to use this QXmlQuery to process XSL-T stylesheets. The other constructor must be used in that case.


QXmlQuery

public QXmlQuery(QXmlQuery.QueryLanguage queryLanguage)
Constructs a query that will be used to run Xqueries or XSL-T stylesheets, depending on the value of queryLanguage. It will use np as its name pool.

Note: If your QXmlQuery will process XSL-T stylesheets, this constructor must be used. The default constructor can only create instances of QXmlQuery for running XQueries.

Note: The XSL-T support in this release is considered experimental. See the XSLT conformance for details.

See also:
queryLanguage().


QXmlQuery

public QXmlQuery(QXmlQuery.QueryLanguage queryLanguage,
                 QXmlNamePool np)
Constructs a query that will be used to run Xqueries or XSL-T stylesheets, depending on the value of queryLanguage. It will use np as its name pool.

Note: If your QXmlQuery will process XSL-T stylesheets, this constructor must be used. The default constructor can only create instances of QXmlQuery for running XQueries.

Note: The XSL-T support in this release is considered experimental. See the XSLT conformance for details.

See also:
queryLanguage().


QXmlQuery

public QXmlQuery(QXmlNamePool np)
Constructs a query that will use np as its name pool. The query cannot be evaluated until setQuery() has been called.


QXmlQuery

public QXmlQuery(QXmlQuery other)
Constructs a QXmlQuery that is a copy of other. The new instance will share resources with the existing query to the extent possible.

Method Detail

bindVariable

public final void bindVariable(java.lang.String localName,
                               QIODevice arg__2)
This is an overloaded member function, provided for convenience.

If localName is a valid NCName, this function is equivalent to the following snippet.

    query.bindVariable(new QXmlName(query.namePool(), localName), device);
A QXmlName is constructed from localName, and is passed to the appropriate overload along with device.

See also:
QXmlName::isNCName().


bindVariable

public final void bindVariable(java.lang.String localName,
                               QXmlItem value)
This is an overloaded member function, provided for convenience.

This function constructs a QXmlName from localName using the query's namespace. The function then behaves as the overloaded function. It is equivalent to the following snippet.

    query.bindVariable(new QXmlName(query.namePool(), localName), value);


bindVariable

public final void bindVariable(java.lang.String localName,
                               QXmlQuery query)
This is an overloaded member function, provided for convenience.

Has the same behavior and effects as the function being overloaded, but takes the variable name localName as a QString. query is used as in the overloaded function.


bindVariable

public final void bindVariable(QXmlName name,
                               QIODevice arg__2)
Binds the variable name to the device so that $name can be used from within the query to refer to the device. The QIODevicedevice is exposed to the query as a URI of type xs:anyURI, which can be passed to the fn:doc() function to be read. E.g., this function can be used to pass an XML document in memory to fn:doc.
    QByteArray myDocument = new QByteArray();
    QBuffer buffer = new QBuffer(myDocument); // This is a QIODevice.
    buffer.open(QIODevice.OpenModeFlag.ReadOnly);
    QXmlQuery query = new QXmlQuery();
    query.bindVariable("myDocument", buffer);
    query.setQuery("declare variable $myDocument external; doc($myDocument)");
The caller must ensure that device has been opened with at least QIODevice::ReadOnly prior to this binding. Otherwise, behavior is undefined.

If the query will access an XML document contained in a QString, use a QBuffer as shown in the following snippet. Suppose myQString contains <document>content</document>

The following code example is written in c++.

    QBuffer device;
    device.setData(myQString.toUtf8());
    device.open(QIODevice::ReadOnly);

    QXmlQuery query;
    query.setQuery("doc($inputDocument)/query[theDocument]");
    query.bindVariable("inputDocument", &device);
name must not be null. name.isNull() must return false. If name has already been bound, its previous binding will be overridden. The URI that name evaluates to is arbitrary and may change.

If the type of the variable binding changes (e.g., if a previous binding by the same name was a QVariant, or if there was no previous binding), isValid() will return false, and recompilation of the query text is required. To recompile the query, call setQuery(). For this reason, bindVariable() should be called before setQuery(), if possible.

Note:device must not be deleted while this QXmlQuery exists.


bindVariable

public final void bindVariable(QXmlName name,
                               QXmlItem value)
Binds the variable name to the value so that $name can be used from within the query to refer to the value.

name must not be null. name.isNull() must return false. If name has already been bound by a previous bindVariable() call, its previous binding will be overridden.

If value is null so that value.isNull() returns true, and name already has a binding, the effect is to remove the existing binding for name.

To bind a value of type QString or QUrl, wrap the value in a QVariant such that QXmlItem's QVariant constructor is called.

All strings processed by the query must be valid XQuery strings, which means they must contain only XML 1.0 characters. However, this requirement is not checked. If the query processes an invalid string, the behavior is undefined.

See also:
QVariant::isValid(), How QVariant maps to XQuery's Data Model, and QXmlItem::isNull().


bindVariable

public final void bindVariable(QXmlName name,
                               QXmlQuery query)
Binds the result of the query query, to a variable by name name.

Evaluation of query will be commenced when this function is called.

If query is invalid, behavior is undefined. query will be copied.

See also:
isValid().


evaluateTo

public final boolean evaluateTo(QIODevice target)
Evaluates the query or stylesheet, and writes the output to target.

QXmlSerializer is used to write the output to target. In a future release, it is expected that this function will be changed to respect serialization options set in the stylesheet.

If an error occurs during the evaluation, error messages are sent to messageHandler() and false is returned.

If target is null, or is not opened in at least QIODevice::WriteOnly mode, the behavior is undefined. QXmlQuery does not take ownership of target.

This is an overloaded member function, provided for convenience.


evaluateTo

public final void evaluateTo(QXmlResultItems result)
Starts the evaluation and makes it available in result. If result is null, the behavior is undefined. The evaluation takes place incrementally (lazy evaluation), as the caller uses QXmlResultItems::next() to get the next result.

See also:
QXmlResultItems::next().


initialTemplateName

public final QXmlName initialTemplateName()
Returns the name of the XSL-T stylesheet template that the processor will call first when running an XSL-T stylesheet. This function only applies when using QXmlQuery to process XSL-T stylesheets. By default, no initial template is set. In that case, a default constructed QXmlName is returned.

See also:
setInitialTemplateName().


isValid

public final boolean isValid()
Returns true if this query is valid. Examples of invalid queries are ones that contain syntax errors or that have not had setQuery() called for them yet.


messageHandler

public final QAbstractMessageHandler messageHandler()
Returns the message handler that handles compile and runtime messages for this QXmlQuery.

See also:
setMessageHandler().


namePool

public final QXmlNamePool namePool()
Returns the name pool used by this QXmlQuery for constructing names. There is no setter for the name pool, because mixing name pools causes errors due to name confusion.


networkAccessManager

public final QNetworkAccessManager networkAccessManager()
Returns the network manager, or 0 if it has not been set.

See also:
setNetworkAccessManager().


operator_assign

public final QXmlQuery operator_assign(QXmlQuery other)
Assigns other to this QXmlQuery instance.


queryLanguage

public final QXmlQuery.QueryLanguage queryLanguage()
Returns a value indicating what this QXmlQuery is being used for. The default is QXmlQuery::XQuery10 , which means the QXmlQuery is being used for running XQuery and XPath queries. QXmlQuery::XSLT20 can also be returned, which indicates the QXmlQuery is for running XSL-T spreadsheets.


setFocus

public final boolean setFocus(QIODevice document)
Sets the focus to be the document read from the QIODevice and returns true. If document cannot be loaded, false is returned.

QXmlQuery does not take ownership of document. The user guarantees that a document is available from the document device and that the document is not empty. The device must be opened in at least read-only mode. document must stay in scope as long as the current query is active.

This is an overloaded member function, provided for convenience.


setFocus

public final boolean setFocus(QUrl documentURI)
This is an overloaded member function, provided for convenience.

Sets the focus to be the document located at documentURI and returns true. If documentURI cannot be loaded, false is returned. It is undefined at what time the document may be loaded. When loading the document, the message handler and URI resolver set on this QXmlQuery are used.

If documentURI is empty or is not a valid URI, the behavior of this function is undefined.


setFocus

public final void setFocus(QXmlItem item)
Sets the focus to item. The focus is the set of items that the context item expression and path expressions navigate from. For example, in the expression p/span, the element that p evaluates to is the focus for the following expression, span.

The focus can be accessed using the context item expression, i.e., dot (".").

By default, the focus is not set and is undefined. It will therefore result in a dynamic error, XPDY0002, if the focus is attempted to be accessed. The focus must be set before the query is set with setQuery().

There is no behavior defined for setting an item which is null.


setInitialTemplateName

public final void setInitialTemplateName(java.lang.String name)
This is an overloaded member function, provided for convenience.

Sets the name of the initial template to localName, which must be a valid local name. The initial template is the one the processor calls first, instead of attempting to match a template to the context node (if any). If an initial template is not set, the standard order of template invocation will be used.

This function only applies when using QXmlQuery to process XSL-T stylesheets. The name becomes part of the compiled stylesheet. Therefore, this function must be called before calling setQuery().

If localName is not a valid local name, the effect is undefined. If the stylesheet has no template named localName, the processor will use the standard order of template invocation.

See also:
initialTemplateName().


setInitialTemplateName

public final void setInitialTemplateName(QXmlName name)
Sets the name of the initial template. The initial template is the one the processor calls first, instead of attempting to match a template to the context node (if any). If an initial template is not set, the standard order of template invocation will be used.

This function only applies when using QXmlQuery to process XSL-T stylesheets. The name becomes part of the compiled stylesheet. Therefore, this function must be called before calling setQuery().

If the stylesheet has no template named name, the processor will use the standard order of template invocation.

See also:
initialTemplateName().


setMessageHandler

public final void setMessageHandler(QAbstractMessageHandler messageHandler)
Changes the message handler for this QXmlQuery to aMessageHandler. The query sends all compile and runtime messages to this message handler. QXmlQuery does not take ownership of aMessageHandler.

Normally, the default message handler is sufficient. It writes compile and runtime messages to stderr. The default message handler includes color codes if stderr can render colors.

Note that changing the message handler after the query has been compiled has no effect, i.e. the query uses the same message handler at runtime that it uses at compile time.

When QXmlQuery calls QAbstractMessageHandler::message(), the arguments are as follows:

message() argument
Semantics
QtMsgType type Only QtWarningMsg and QtFatalMsg are used. The former identifies a compile or runtime warning, while the latter identifies a dynamic or static error.
const QString & description An XHTML document which is the actual message. It is translated into the current language.
const QUrl &identifier Identifies the error with a URI, where the fragment is the error code, and the rest of the URI is the error namespace.
const QSourceLocation & sourceLocation Identifies where the error occurred.

See also:
messageHandler().


setNetworkAccessManager

public final void setNetworkAccessManager(QNetworkAccessManager newManager)
Sets the network manager to newManager. QXmlQuery does not take ownership of newManager.

See also:
networkAccessManager().


setQuery

public final void setQuery(QIODevice sourceCode)
Sets this QXmlQuery to an XQuery read from the sourceCode device. The device must have been opened with at least QIODevice::ReadOnly .

documentURI represents the query obtained from the sourceCode device. It is the base URI of the static context, as defined in the XQuery language. It is used internally to resolve relative URIs that appear in the query, and for message reporting. documentURI can be empty. If it is empty, the application file path is used. If it is not empty, it may be either relative or absolute. If it is relative, it is resolved itself against the application file path before it is used. If documentURI is neither a valid URI nor empty, the result is undefined.

If the query contains a static error (e.g. syntax error), an error message is sent to the messageHandler(), and isValid() will return false.

Variables must be bound before setQuery() is called.

The encoding of the XQuery in sourceCode is detected internally using the rules for setting and detecting encoding of XQuery files, which are explained in the XQuery language.

If sourceCode is null or not readable, or if documentURI is not a valid URI, behavior is undefined.

See also:
isValid().


setQuery

public final void setQuery(QIODevice sourceCode,
                           QUrl documentURI)
Sets this QXmlQuery to an XQuery read from the sourceCode device. The device must have been opened with at least QIODevice::ReadOnly .

documentURI represents the query obtained from the sourceCode device. It is the base URI of the static context, as defined in the XQuery language. It is used internally to resolve relative URIs that appear in the query, and for message reporting. documentURI can be empty. If it is empty, the application file path is used. If it is not empty, it may be either relative or absolute. If it is relative, it is resolved itself against the application file path before it is used. If documentURI is neither a valid URI nor empty, the result is undefined.

If the query contains a static error (e.g. syntax error), an error message is sent to the messageHandler(), and isValid() will return false.

Variables must be bound before setQuery() is called.

The encoding of the XQuery in sourceCode is detected internally using the rules for setting and detecting encoding of XQuery files, which are explained in the XQuery language.

If sourceCode is null or not readable, or if documentURI is not a valid URI, behavior is undefined.

See also:
isValid().


setQuery

public final void setQuery(java.lang.String sourceCode)
This is an overloaded member function, provided for convenience.

The behavior and requirements of this function are the same as for setQuery(QIODevice*, const QUrl&), after the XQuery has been read from the IO device into a string. Because sourceCode is already a Unicode string, detection of its encoding is unnecessary.


setQuery

public final void setQuery(java.lang.String sourceCode,
                           QUrl documentURI)
This is an overloaded member function, provided for convenience.

The behavior and requirements of this function are the same as for setQuery(QIODevice*, const QUrl&), after the XQuery has been read from the IO device into a string. Because sourceCode is already a Unicode string, detection of its encoding is unnecessary.


setQuery

public final void setQuery(QUrl queryURI)
Sets this QXmlQuery to the XQuery read from the queryURI. Use isValid() after calling this function. If an error occurred reading queryURI, e.g., the query does not exist, cannot be read, or is invalid, isValid() will return false.

The supported URI schemes are the same as those in the XQuery function fn:doc, except that queryURI can be the object of a variable binding.

baseURI is the Base URI of the static context, as defined in the XQuery language. It is used internally to resolve relative URIs that appear in the query, and for message reporting. If baseURI is empty, queryURI is used. Otherwise, baseURI is used, and it is resolved against the application file path if it is relative.

If queryURI is empty or invalid, or if baseURI is invalid, the behavior of this function is undefined.


setQuery

public final void setQuery(QUrl queryURI,
                           QUrl baseURI)
Sets this QXmlQuery to the XQuery read from the queryURI. Use isValid() after calling this function. If an error occurred reading queryURI, e.g., the query does not exist, cannot be read, or is invalid, isValid() will return false.

The supported URI schemes are the same as those in the XQuery function fn:doc, except that queryURI can be the object of a variable binding.

baseURI is the Base URI of the static context, as defined in the XQuery language. It is used internally to resolve relative URIs that appear in the query, and for message reporting. If baseURI is empty, queryURI is used. Otherwise, baseURI is used, and it is resolved against the application file path if it is relative.

If queryURI is empty or invalid, or if baseURI is invalid, the behavior of this function is undefined.


setUriResolver

public final void setUriResolver(QAbstractUriResolver resolver)
Sets the URI resolver to resolver. QXmlQuery does not take ownership of resolver.

See also:
uriResolver().


uriResolver

public final QAbstractUriResolver uriResolver()
Returns the query's URI resolver. If no URI resolver has been set, QtXmlPatterns will use the URIs in queries as they are.

The URI resolver provides a level of abstraction, or polymorphic URIs. A resolver can rewrite logical URIs to physical ones, or it can translate obsolete or invalid URIs to valid ones.

QtXmlPatterns calls the URI resolver for all URIs it encounters, except for namespaces. Specifically, all builtin functions that deal with URIs (fn:doc(), and fn:doc-available()).

In the case of fn:doc(), the absolute URI is the base URI in the static context (which most likely is the location of the query). Rather than use the URI the user specified, the return value of QAbstractUriResolver::resolve() will be used.

When QtXmlPatterns calls QAbstractUriResolver::resolve() the absolute URI is the URI mandated by the XQuery language, and the relative URI is the URI specified by the user.

See also:
setUriResolver().


evaluateTo

public final java.lang.String evaluateTo()
This is an overloaded method provided for convenience.