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POChaining Foreign Keys
 

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    <p>I have a few models that look like this:</p> <pre><code>class System(models.Model): '''Defines a system''' system_desc = models.CharField('System Name', max_length=50) class SystemGroup(models.Model): '''Groups within a 'System' (ie. Customers, regions, divisions, etc. ''' group_desc = models.CharField('Group Name',max_length=25) system = models.ForeignKey(System) class QueryData(models.Model): '''Queries related to a 'System' (ie. Active users against System1, Orders today in system2, etc. ''' qry_desc = models.CharField('Query Description', max_length=50) system = models.ForeignKey(System) class UserDashboard(models.Model): '''User specific Dashboard ''' user = models.ForeignKey(User) board_name = models.CharField('Dashboard Name', max_length=50) class UserDashboardGroup(models.Model): '''Groups on the dashboard (ie. 'System 1's Key Indicators', 'System 2's Hot Sheet', etc. ''' group_desc = models.CharField('Group Display Title', max_length=50) user = models.ForeignKey(User) dashboard = models.ForeignKey(UserDashboard) system = models.ForeignKey(System) system_group = models.ForeignKey(SystemGroup) class UserGroupQuery(models.Model): '''Queries that run in a specific group on the dashboard (ie. Within 'System 1's Key Indicators, we run queries for active users today, orders in the last hour, etc. ''' user = models.ForeignKey(User) dashboard = ChainedForeignKey(UserDashboard, chained_field='user', chained_model_field='user', show_all=False, auto_choose=True) user_dashboard_group = ChainedForeignKey(UserDashboardGroup, chained_field='dashboard', chained_model_field='dashboard') query = models.ForeignKey(QueryData) </code></pre> <p>I am having problems with the very last part of this. I want to restrict the 'query' that appears in a admin page based on the selected <code>user_dashboard_group</code>. I'm not sure how I can do this, based on my current models though. <code>query</code> and <code>user_dashboard_group</code> both have a foreign key to <code>System</code>, but not to each other. To get this though, I'd have to get the <code>user_dashboard_group</code>'s <code>system</code> and then use that to filter the <code>QueryData</code>. How can I do this?</p> <p><strong>Edit</strong> I'm adding in a picture to (hopefully) describe a little better what I want to do. In step 1, the user inputs a name for this group of queries. This group is associated with a system (#2) and a predefined group within the system (#3) (think of #3 as a 'customer' or a 'region', etc and #1 and #3 are NOT the same thing, despite the similar naming). They then select 'Save and Continue editing' on this inline form and the drop down at step 4 becomes populated with information from the above form. Once step #4 has a selection made, I want #5 to populate with data only from the associated system. Since #2 contains this information, I am hoping it is fairly easy to do this, but I can't figure out the chaining. </p> <p><img src="https://i.stack.imgur.com/RnCKj.png" alt="Demo dashboard"></p> <p>I also realized that I didn't mention I was using <a href="https://github.com/digi604/django-smart-selects/" rel="nofollow noreferrer">django-smart-selects</a></p>
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