XEO Guide Lines

This document is intended to explain some of the guidelines you should follow to avoid running into problems, or just to make things the right way.

XEO Object Model and Attribute Names length limitation

XEO generates database tables to support persistence of XEO Model instances and relations between them. Historically there was a limitation in XEO that database tables must have a name length inferior to 30 characters. There is a convention in XEO to create a table name with the XEO Model name, and when there's a 1:N relation with another XEO Model through an attribute named "relation" the database table created to support that relation will be named XEOModelName$attributeName.

So, if we have a XEO Model "book" with a collection attribute to XEO Model "author", named authors, the database table created will be "book$authors". Because of the 30 characters limitation you should not create Object Model names nor attribute names with very long names, or you'll have a problem when executing your application. Queries may fail, or not behave as you expect. This is a situation that's in our roadmap to fix.

In short, XEO Model names and attribute names should not exceed 14 characters each. So that when database tables for 1:N relations are created, the maximum of 30 characters is not exceeded.