ODF Documents

DataNucleus supports persisting/retrieving objects to/from ODF documents (using the datanucleus-odf plugin) which makes use of the ODFDOM project. Simply specify your "connectionURL" as follows

datanucleus.ConnectionURL=odf:file:myfile.ods

replacing "myfile.ods" with your filename, which can be absolute or relative. This connects to a file on your local machine. You then create your PMF/EMF as normal and use JDO/JPA as normal.

There are tutorials available for use of DataNucleus with ODF for JDO and for JPA

Things to bear in mind with ODF usage :-

  • Querying can be performed using JDOQL or JPQL. Any filtering/ordering will be performed in-memory
  • Relations : A spreadsheet cannot store related objects directly, since each object is a row of a particular worksheet. DataNucleus gets around this by storing the String-form of the identity of the related object in the relation cell. See



Worksheet Headers

A typical spreadsheet has many rows of data. It contains no names of columns tying the data back to the input object (field names). DataNucleus allows an extension specified at class level called include-column-headers (should be set to true). When the table is then created it will include an extra row (the first row) with the column names from the metadata (or field names if no column names were defined). For example