= Frequently Asked Questions (FAQ) =

== Frequently Encountered Problems ==

If it happens that you notice the following in the Traceback of the ticket encountered after a fresh pull -[[BR]]
{{{OperationalError: Cannot add a UNIQUE column}}} [[BR]] [[BR]]
Then it is highly likely that there is a data migration issue. In this circumstance, it is recommended that the contents of the folder /eden/database/ be deleted. For more, information in this regard and any other related problem, the following links can be referred from -[[BR]]
http://eden.sahanafoundation.org/wiki/TroubleShooting
[[BR]]
http://eden.sahanafoundation.org/wiki/DataMigration

== Select Element for Users ==
By: Robby O'Connor[[BR]]
Date: 2010-05-21[[BR]]

To have a field displayed as a select element which has the names of the users in the database:
{{{
<table>.<field>.requires = IS_NULL_OR(IS_IN_DB(db,db.auth_user.id,lambda id : shn_user_represent(db.auth_user.id)))
}}}

== Interactive vs. Non-Interactive Functions ==
 * '''Interactive''' = via web browser (html)
 * '''Non-Interactive''' = Sync, import, etc (xml, csv)

Never do a redirect or create records (the latter is slightly less 100%) in non-interactive functions.

All resources should assume to be touched non-interactively at some point (even if just to load test/demo data)

onaccept & onvalidation are always called by non-interactive functions

Protect sections within these functions to be only accessed via interactive calls using:
{{{
if isinstance(form, FORM):
    # Interactive request
}}}
DeveloperGuidelines
DeveloperGuidelines