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This example shows how to use composite value types as data members in objects
and other value types, as element types in containers, and as base types for
other composite value types. It also shows how to use composite value type
data members in queries.
The example consists of the following files:
person.hxx
Header file defining the 'basic_name', 'name_extras', and 'name' composite
value types. It also defines the 'phone_numbers' composite value type as
an instantiation of the 'std::pair' class template. Finally it defines
the 'person' persistent class which uses the 'name' and 'phone_numbers'
value types in its data members.
person-odb.hxx
person-odb.ixx
person-odb.cxx
person.sql
The first three files contain the database support code and the last file
contains the database schema for the person.hxx header.
These files are generated by the ODB compiler from person.hxx using the
following command line:
odb -d <database> --generate-schema --generate-query person.hxx
Where <database> stands for the database system we are using, for example,
'mysql'.
database.hxx
Contains the create_database() function which instantiates the concrete
database class corresponding to the database system we are using.
driver.cxx
Driver for the example. It includes the person.hxx and person-odb.hxx
headers to gain access to the persistent classes and their database support
code. It also includes database.hxx for the create_database() function
declaration.
In main() the driver first calls create_database() to obtain the database
instance. It then persists a 'person' object, loads it and updates its
nickname and aliases which reside in a composite value type, then re-loads
the object and prints its name to verify that the changes have been made
persistent. Finally, the driver performs a database query which uses a
data member from the composite value type in its criterion.
To run the example we may first need to create the database schema (for some
database systems, such as SQLite, the schema is embedded into the generated
code which makes this step unnecessary). Using MySQL as an example, this
can be achieved with the following command:
mysql --user=odb_test --database=odb_test < person.sql
Here we use 'odb_test' as the database login and also 'odb_test' as the
database name.
Once the database schema is ready, we can run the example (using MySQL as
the database):
./driver --user odb_test --database odb_test
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