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public interface ValueMaker
Describes a set of strings that are obtained in some way from one or more database columns.
Typical implementations are ColumnValueMaker
(describing the set
of strings contained in one database column), TemplateValueMaker
(describing the set of strings that is obtained by sticking
the values of several database fields into a string pattern),
and BlankNodeIDValueMaker
(similar).
There are several other implementations that modify the behaviour
of another underlying ValueMaker, implementing the Decorator
pattern. This includes TranslationTable
, TranslatingValueMaker
(translates values using a translation table or translation class)
and the various value restrictions (@link RegexRestriction et. al.).
ValueMakers are used by NodeMakers. A node maker wraps the strings into Jena nodes, thus creating a description of a set of RDF nodes.
Field Summary | |
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static ValueMaker |
NULL
A value maker that never produces a value. |
Method Summary | |
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void |
describeSelf(NodeSetFilter c)
|
String |
makeValue(ResultRow row)
Retrieves a value from a database row according to some rule or pattern. |
boolean |
matches(String value)
Indicates whether the node maker is capable of producing a given value, as far as can be told without having access to the actual database. |
List<OrderOp.OrderSpec> |
orderSpecs(boolean ascending)
|
Set<ProjectionSpec> |
projectionSpecs()
Returns a set of all ProjectionSpec s containing data necessary
for this ValueSource. |
ValueMaker |
rename(Renamer renamer)
|
Expression |
valueExpression(String value,
DatabaseOp tabular,
Vendor vendor)
A SQL expression that selects only rows where this value maker produces the specified value. |
Field Detail |
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static final ValueMaker NULL
Method Detail |
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boolean matches(String value)
true
iff this node maker is capable of producing the valueExpression valueExpression(String value, DatabaseOp tabular, Vendor vendor)
Expression.FALSE
if this
value maker is incapable of producing the value.
value
- A valuetabular
- The table to which the expression will be applicablevendor
- A vendor instance for datatyping etc.
Set<ProjectionSpec> projectionSpecs()
ProjectionSpec
s containing data necessary
for this ValueSource.
ProjectionSpec
sString makeValue(ResultRow row)
row
- the database row
void describeSelf(NodeSetFilter c)
ValueMaker rename(Renamer renamer)
List<OrderOp.OrderSpec> orderSpecs(boolean ascending)
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