= CiviCRM HowTo Develop API

Tags: [[CiviCRM]] [[HowTo]]

Just some quick notes for now:

1. API files live in the folder {{{{drupal}\sites\all\modules\civicrm\api\v3}}}
1. Custom API files live in the folder {{{{civicrm custom folder}\api\v3}}} (CiviCRM custom folder is defined in the Civi menu Admininster >> System Settings >> Directories as {{{Custom PHP Path Directory}}}).  These files are used in preference to the ones in the standard folder above.
1. The file name for API files should be Entity.php.  The function name is civicrm_api3_entity_action.
1. The get methods seem to use a few standard mechanisms, some using functions in the file utils.php in the same api/v3 directory.
1. One standard mechanism is that {{{_civicrm_api3_basic_create}}} function in the utils.php file.  This searches for entities, filtering by their field values.
1. Quite a few use this method mixed, but add functionality to search for entities based on linked entities.  E.g, Activities can be found by contact_id, which is a relationship, not a field.  The two methods do not play nicely together.  For example, try searching for Activities by contact_id and activity_type_id - the activity_type_id filter will be ignored.

== Investigations

1. [[CiviCRM API - Adding Custom Values to Case Get]]

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