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The following page has been changed by KevinWilliams: http://wiki.apache.org/ws/Tuscany/TuscanyJava/DAS_Java_Overview/RDBDAS_Java_User_Guide/Convention_over_configuration ------------------------------------------------------------------------------ ADDRESS VARCHAR(30) }}} + If an application uses the DAS to query this table with the following SQL statement: + {{{ + SELECT * FROM CUSTOMER + }}} + The DAS will return a graph of !DataObjects each of Type CUSTOMER and each instance in will have three properties: (ID, LASTNAME, ADDRESS). Here is the example code. Note that no configuration data is provided at all. - As an example, the RDB DAS must know how a !DataObject's properties map to a database table key in order to generate the INSERT/UPDATE and DELETE statements necessary to flush a data graph's changes to a database. In typical Object/Relational mappings frameworks, this information is provided in a config file with something like this: + {{{ + DAS das = DAS.FACTORY.createDAS(getConnection()); + Command readCustomers = das.createCommand("select * from CUSTOMER"); + DataObject root = readCustomers.executeQuery(); + }}} + + Another piece of convention followed by the RDB DAS has to do with database table keys. The RDB DAS scans the SDO !ChangeSummery and generates the set of INSERT/UPDATE and DELETE statements needed to flush the graph changes to the database. To generate the correct statements the RDB DAS needs to know how a !DataObject's properties map to a database table key. In typical Object/Relational mappings frameworks, this information is provided in a config file with something like this: {{{ <Table tableName="COMPANY"> @@ -27, +38 @@ </Table> }}} - One convention the RDB DAS understands is that if a !DataObject has a property named "ID" then it can assume that the property maps to a key column in the database. So, if a developer follows this convention (naming key columns in database tables "ID") then this key-mapping information need not be specified in a configuration file. + However, the RDB DAS understands is that, in the absence of user provided cofiguration data, if a !DataObject has a property named "ID" then it can assume that it maps to a key column in the database. If a developer follows this convention (naming key columns in database tables "ID") then this key-mapping information need not be specified in a configuration file. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
