Nepomuk::Query::QueryServiceClient Class Reference

#include <Nepomuk/Query/QueryServiceClient>

Inheritance diagram for Nepomuk::Query::QueryServiceClient:

Public Slots
bool	blockingDesktopQuery (const QString &query)
bool	blockingQuery (const Query &query)
bool	blockingSparqlQuery (const QString &query, const Nepomuk::Query::RequestPropertyMap &requestPropertyMap=Nepomuk::Query::RequestPropertyMap())
void	close ()
bool	desktopQuery (const QString &query)
QString	errorMessage () const
bool	isListingFinished () const
bool	query (const Query &query)
bool	sparqlQuery (const QString &query, const Nepomuk::Query::RequestPropertyMap &requestPropertyMap=Nepomuk::Query::RequestPropertyMap())

Signals
void	entriesRemoved (const QList< QUrl > &entries)
void	error (const QString &errorMessage)
void	finishedListing ()
void	newEntries (const QList< Nepomuk::Query::Result > &entries)
void	resultCount (int count)
void	serviceAvailabilityChanged (bool running)

Public Member Functions
	QueryServiceClient (QObject *parent=0)
	~QueryServiceClient ()

Static Public Member Functions
static bool	serviceAvailable ()
static QList < Nepomuk::Query::Result >	syncDesktopQuery (const QString &query, bool *ok=0)
static QList < Nepomuk::Query::Result >	syncQuery (const Query &query, bool *ok=0)
static QList < Nepomuk::Query::Result >	syncSparqlQuery (const QString &query, const Nepomuk::Query::RequestPropertyMap &requestPropertyMap=Nepomuk::Query::RequestPropertyMap(), bool *ok=0)

Detailed Description

Convenience frontend to the Nepomuk Query DBus Service.

The QueryServiceClient provides an easy way to access the Nepomuk Query Service without having to deal with any communication details. By default it monitors queries for changes.

Usage is simple: Create an instance of the client for each search you want to track. One instance may also be reused for subsequent queries if further updates of the persistent query are not necessary.

For quick queries which do not require any updates one of the static query methods can be used: syncQuery(), syncSparqlQuery(), or syncDesktopQuery().

Author

Sebastian Trueg trueg.nosp@m.@kde.nosp@m..org

Since

4.4

Definition at line 58 of file queryserviceclient.h.

Constructor & Destructor Documentation

Nepomuk::Query::QueryServiceClient::QueryServiceClient

(

QObject *

parent = 0

)

Create a new QueryServiceClient instance.

Nepomuk::Query::QueryServiceClient::~QueryServiceClient

(

)

Desctructor.

Closes the query.

Member Function Documentation

bool Nepomuk::Query::QueryServiceClient::blockingDesktopQuery ( const QString &  query )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query

a desktop query string which can be parsed by QueryParser.

See also

desktopQuery(const QString&), close()

bool Nepomuk::Query::QueryServiceClient::blockingQuery ( const Query &  query )

slot

Start a query using the Nepomuk query service.

Results will be reported as with query(const QString&) but a local event loop will be started to block the method call until all results have been listed.

The client will be closed after the initial listing. Thus, changes to results will not be reported as it is the case with the non-blocking methods.

Parameters

query

the query to perform.

Returns

true if the query service was found and the query was started. false otherwise.

See also

query(const Query&), close()

bool Nepomuk::Query::QueryServiceClient::blockingSparqlQuery ( const QString &  query, const Nepomuk::Query::RequestPropertyMap &  requestPropertyMap = Nepomuk::Query::RequestPropertyMap()  )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query	a SPARQL query which binds results to variable 'r'.
requestPropertyMap	An optional mapping of variable binding names in query to their corresponding properties. For details see sparqlQuery.

See also

sparqlQuery(const Query&)

void Nepomuk::Query::QueryServiceClient::close ( )

slot

Close the client, thus stop to monitor the query for changes.

Without closing the client it will continue signalling changes to the results.

This will also make any blockingQuery return immediately.

bool Nepomuk::Query::QueryServiceClient::desktopQuery ( const QString &  query )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query

a desktop query string which can be parsed by QueryParser.

void Nepomuk::Query::QueryServiceClient::entriesRemoved ( const QList< QUrl > &  entries )

signal

Emitted if the search results changed when monitoring a query.

Parameters

entries

A list of resource URIs identifying the resources that dropped out of the query results.

void Nepomuk::Query::QueryServiceClient::error ( const QString &  errorMessage )

signal

Emitted when an error occurs.

This typically happens in case the query service is not running or does not respond. No further signals will be emitted after this one.

Since

4.6

QString Nepomuk::Query::QueryServiceClient::errorMessage ( ) const

slot

The last error message which has been emitted via error() or an empty string if there was no error.

Since

4.6

void Nepomuk::Query::QueryServiceClient::finishedListing ( )

signal

Emitted when the initial listing has been finished, ie.

if all results have been reported via newEntries. If no further updates are necessary the client should be closed now.

In case of an error this signal is not emitted.

See also

error()

bool Nepomuk::Query::QueryServiceClient::isListingFinished ( ) const

slot

Returns

true if all results have been listed (ie. finishedListing() has been emitted), close() has been called, or no query was started.

Since

4.6

void Nepomuk::Query::QueryServiceClient::newEntries ( const QList< Nepomuk::Query::Result > &  entries )

signal

Emitted for new search results.

This signal is emitted both for the initial listing and for changes to the search.

bool Nepomuk::Query::QueryServiceClient::query ( const Query &  query )

slot

Start a query using the Nepomuk query service.

Results will be reported via newEntries. All results have been reported once finishedListing has been emitted.

Parameters

query

the query to perform.

Returns

true if the query service was found and the query was started. false otherwise.

void Nepomuk::Query::QueryServiceClient::resultCount ( int  count )

signal

The number of results that are reported via newEntries() before the finishedListing() signal.

Emitted once the count of the results is available. This might happen before the first result is emitted, in between the results, or in rare cases it could even happen after all results have been reported.

Also be aware that no count will be provided when using sparqlQuery()

Since

4.6

void Nepomuk::Query::QueryServiceClient::serviceAvailabilityChanged ( bool  running )

signal

Emitted when the availability of the query service changes.

Since

4.8

static bool Nepomuk::Query::QueryServiceClient::serviceAvailable ( )

static

Check if the Nepomuk query service is running.

Returns

true if the Nepomuk query service is running and could be contacted via DBus, false otherwise

bool Nepomuk::Query::QueryServiceClient::sparqlQuery ( const QString &  query, const Nepomuk::Query::RequestPropertyMap &  requestPropertyMap = Nepomuk::Query::RequestPropertyMap()  )

slot

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query	a SPARQL query which binds results to variable 'r'.
requestPropertyMap	An optional mapping of variable binding names in query to their corresponding properties. These bindings will then be reported via Result::requestProperties(). This map will be constructed automatically when using query(const Query&).

Examples:

Select a simple request property as can also be done via Query::Query:

QString query = "select ?r ?mtime where { "
                "?r a nfo:FileDataObject . "
                "?r nie:lastModified ?mtime . "
                "}";

QueryServiceClient::RequestPropertyMap requestPropertyMap;
requestPropertyMap.insert( "mtime", Vocabulary::NIE::lastModified() );

sparqlQuery( query, requestPropertyMap );

This will report the resources themselves and their modification time in the result's request properties:

void handleResult( const Query::Result& results ) {
    QDateTime lastModified = result.requestProperty( Vocabulary::NIE::lastModified() ).toDateTime();
    [...]

While using Query::Query restricts to request properties to diret properties of the results using a custom SPARQL query allows to use any binding as request property. The used property URI in the mapping does not even need to match anything in the query:

QString query = "select ?r ?phone where { "
                "?r a nco:PersonContact . "
                "?r nco:hasPhoneNumber ?n . "
                "?n nco:phoneNumber ?phone . "
                "}";

QueryServiceClient::RequestPropertyMap requestPropertyMap;
requestPropertyMap.insert( "phone", Vocabulary::NCO::hasPhoneNumber() );

See also

Query::requestPropertyMap()

static QList<Nepomuk::Query::Result> Nepomuk::Query::QueryServiceClient::syncDesktopQuery ( const QString &  query, bool *  ok = 0  )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query	a desktop query string which can be parsed by QueryParser.
ok	a valid boolean pointer, which will be set to true if the query service was found and the query was started, false otherwise. If you don't want to track errors, you can pass a null pointer instead.

See also

desktopQuery(const QString&)

Since

4.5

static QList<Nepomuk::Query::Result> Nepomuk::Query::QueryServiceClient::syncQuery ( const Query &  query, bool *  ok = 0  )

static

Start a query using the Nepomuk query service.

A local event loop will be started to block the method call until all results have been listed, and results will be returned. You can check if the query was successful through the ok pointer.

If updates to the query results are required an instance of QueryServiceClient should be created and one of the non-static query methods be used.

Parameters

query	the query to perform.
ok	a valid boolean pointer, which will be set to true if the query service was found and the query was started, false otherwise. If you don't want to track errors, you can pass a null pointer instead.

Returns

a list of Result for the given query.

See also

query(const Query&)

Since

4.5

static QList<Nepomuk::Query::Result> Nepomuk::Query::QueryServiceClient::syncSparqlQuery ( const QString &  query, const Nepomuk::Query::RequestPropertyMap &  requestPropertyMap = Nepomuk::Query::RequestPropertyMap(), bool *  ok = 0  )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Parameters

query	a SPARQL query which binds results to variable 'r'.
ok	a valid boolean pointer, which will be set to true if the query service was found and the query was started, false otherwise. If you don't want to track errors, you can pass a null pointer instead.
requestPropertyMap	An optional mapping of variable binding names in query to their corresponding properties. For details see sparqlQuery.

See also

sparqlQuery(const Query&)

Since

4.5

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The documentation for this class was generated from the following file:

• queryserviceclient.h