KDE 4.7 PyKDE API Reference
ComparisonTerm Class Reference
from PyKDE4.nepomuk import *
Inherits: Nepomuk.Query.SimpleTerm → Nepomuk.Query.Term
Namespace: Nepomuk.Query
Detailed Description
\class ComparisonTerm comparisonterm.h Nepomuk/Query/ComparisonTerm
A term matching the value of a property.
The %ComparisonTerm is the most important term in the query API. It can be used to match the values of properties. As such its core components are a property(), a comparator() (see Comparator for details) and a subTerm(). The latter can be any other term including AndTerm, OrTerm, or even an invalid term. The matching is done as follows:
In addition to these basic features %ComparisonTerm has a few tricks up its sleeve:
- Since:
- 4.4
Method Documentation
| __init__ | ( | self ) |
Default constructor: creates a comparison term that matches all properties.
| __init__ | ( | self, | ||
| Nepomuk.Query.ComparisonTerm | term | |||
| ) |
Copy constructor.
| __init__ | ( | self, | ||
| Nepomuk.Types.Property | property, | |||
| Nepomuk.Query.Term | term, | |||
| Nepomuk.Query.ComparisonTerm.Comparator | comparator=Nepomuk.Query.ComparisonTerm.Contains | |||
| ) |
Convinience constructor which covers most simple use cases.
- Parameters:
-
property The property that should be matched. An invalid property will act as a wildcard.
- Parameters:
-
term The sub term to match to.
- Parameters:
-
comparator The Comparator to use for comparison. Not all Comparators make sense with all sub term types.
| Nepomuk.Query.ComparisonTerm.AggregateFunction aggregateFunction | ( | self ) |
The aggregate function to be used with the additional binding set in setVariableName().
\sa setAggregateFunction()
- Since:
- 4.5
| Nepomuk.Query.ComparisonTerm.Comparator comparator | ( | self ) |
The Comparator used by ComparisonTerm Terms.
\sa setComparator
| Nepomuk.Query.ComparisonTerm inverted | ( | self ) |
Create an inverted copy of this %ComparisonTerm. This is a convenience method to allow inline creation of inverted comparison terms when creating queries in a single line of code.
Be aware that calling this method twice wil result in a non-inverted comparison term:
// always true: (term.inverted().inverted() == term);
\sa setInverted()
- Since:
- 4.5
| bool isInverted | ( | self ) |
- Returns:
- true if the comparison is inverted.
- Since:
- 4.5
| Nepomuk.Types.Property property | ( | self ) |
A property used for ComparisonTerm Terms. An invalid property will act as a wildcard.
\sa setProperty
| setAggregateFunction | ( | self, | ||
| Nepomuk.Query.ComparisonTerm.AggregateFunction | function | |||
| ) |
Set an aggregate function which changes the result. The typical usage is to count the results instead of actually returning them. For counting the results of a complete query use Query.CreateCountQuery.
\sa aggregateFunction()
- Since:
- 4.5
| setComparator | ( | self, | ||
| Nepomuk.Query.ComparisonTerm.Comparator | a0 | |||
| ) |
Set the comparator
| setInverted | ( | self, | ||
| bool | invert | |||
| ) |
Invert the comparison, i.e. make the subterm the subject of the term and match to objects of the term.
A typical example would be:
ComparisonTerm term( Soprano.Vocabulary.NAO.hasTag(),
ResourceTerm( somefile ) );
term.setInverted(true);
which would yield a query like the following:
select ?r where { <somefile> nao:hasTag ?r . }
to get all tags attached to a file.
Be aware that this does only make sense with sub terms that match to resources. When using LiteralTerm as a sub term invert is ignored.
\sa inverted()
- Since:
- 4.5
| setProperty | ( | self, | ||
| Nepomuk.Types.Property | a0 | |||
| ) |
Set the property for ComparisonTerm Terms. An invalid property will act as a wildcard.
\sa property
| setSortWeight | ( | self, | ||
| int | weight, | |||
| Qt::SortOrder | sortOrder=Qt.AscendingOrder | |||
| ) |
Set the sort weight of this property. By default all ComparisonTerms have a weight of 0 which means that they are ignored for sorting. By setting \p weight to a value different from 0 (typically higher than 0) the comparison subterm will be used for sorting.
Be aware that as with the variableName() sorting does not apply to sub terms of types ResourceTerm or LiteralTerm. In those cases the value will be ignored. The only exception are LiteralTerm sub terms that are compared other than with equals.
- Parameters:
-
weight The new sort weight. If different from 0 this term will be used for sorting in the Query.
- Parameters:
-
sortOrder The sort order to use for this term.
\sa sortWeight()
- Since:
- 4.5
| setVariableName | ( | self, | ||
| QString | name | |||
| ) |
Set the variable name that is to be used for the variable to match to. The variable will then be added to the set of variables returned in the results and can be read via Result.additionalBinding(). Setting the variable name can be seen as a less restricted variant of Query.addRequestProperty().
When manually setting the variable name on more than one ComparisonTerm there is no guarantee for the uniqueness of variable names anymore which can result in unwanted query results. However, this can also be used deliberately in case one needs to compare the same variable twice:
ComparisonTerm ct1( prop1, Term() ); ComparisonTerm ct1( prop2, Term() ); ct1.setVariableName( "myvar" ); ct2.setVariableName( "myvar" );
The above example would result in a SPARQL query pattern along the lines of
?r <prop1> ?myVar . ?r <prop2> ?myVar .
Be aware that the variable name does not apply to sub terms of types ResourceTerm or LiteralTerm. In those cases the value will be ignored. The only exception are LiteralTerm sub terms that are compared other than with equals.
- Parameters:
-
name The name of the variable to be used when requesting the binding via Result.additionalBinding()
\sa Result.additionalBinding(), Query.HandleInverseProperties, examples_query
- Since:
- 4.5
| Qt::SortOrder sortOrder | ( | self ) |
- Returns:
- The sort order as set in setSortWeight().
- Since:
- 4.5
| int sortWeight | ( | self ) |
- Returns:
- The sort weight as set in setSortWeight() or 0 if sorting is disabled for this term.
- Since:
- 4.5
| QString variableName | ( | self ) |
The variable name set in setVariableName() or an empty string if none has been set.
\sa setVariableName()
- Since:
- 4.5
Enumeration Documentation
| AggregateFunction |
Aggregate functions which can be applied to a comparison term to influence the value they return.
\sa setAggregateFunction()
- Since:
- 4.5
- Enumerator:
-
NoAggregateFunction = 0 Count DistinctCount Max Min Sum DistinctSum Average DistinctAverage
| Comparator |
%ComparisonTerm supports different ways to compare values.
- Enumerator:
-
Contains Regexp Equal Greater Smaller GreaterOrEqual SmallerOrEqual
