Contexts
A context can be defined on a schema element to restrict its
domain of validity to certain instances or property values. This means
mapping cells defined on contexts are not generally in effect, but
only on certain conditions, in a certain context.
As an example, you can use contexts to express a relation like
this:
The type Product in the source schema is the same as
the type Shirt in the target schema if its property type
has the value 'shirt'.
This example can be realised, if a condition context is created
for the type Product, with the condition
type = 'shirt'
, and a Retype
relation is created between the defined Product context and the
Shirt type.
Contexts are defined using expressions and filters in Common Query language (CQL).
Source schema contexts
Types of contexts that can be defined on the source schema.
Condition context
A condition context defines a condition on a type or property,
that is evaluated on the instance or property value respectively. Only
if the condition is fulfilled, an associated mapping takes effect.
Index context
An index context can only be defined on properties that may
occur multiple times. It specifies an index, which references a
certain property value, e.g. the index zero referencing the first
property value, the index one the second, etc.
A mapping associated to an index context only takes effect if an
instance has a property value with the specified index.
Target schema contexts
Types of contexts that can be defined on the target schema.
Instance context
An instance context can similar to an index context only be
defined on properties that may occur multiple times. It represents an
additional property instance that a mapping can use as a target, e.g.
if the same target property is to be populated from the source in
different ways.
Example projects featuring contexts
Type condition context example
Simple example project demonstrating the use of filters on source
types.
The source type item is mapped to two
different target types shirt and hat, according to the
value of the property type.
Property condition context example
Simple example project that demonstrates how a condition on a
source property can be used to map a source property to different
target properties depending on its value.
Index context example
Small example project demonstrating the use of an index context for
source properties.
In the source type placeNames the
information on the name language is given only implicitly through
the name order. The first name is in German, the second in English,
the third in Italian.In the target type explicitNames there
are explicit name properties for each language defined.
