INSERT data into Join/Junction Table

I have three tables in a Postgres database - Titles, Attributes, and Titles_Attributes_Join. The Titles table contains a list of titles and the Attributes table contains a list of attributes. The Titles_Attributes_Join table is a JOIN/JUNCTION table that stores the primary keys for titles and attributes so I can have a MANY TO MANY lookup. My question is how in AppSmith would I build an interface so when you select a Title and an Attribute it would update the Titles_Attributes_Join table?

Hi Jeff and welcome to our community! I think the solution would be to use 2 select widgets that load the data from Titles and Attributes each, then after selecting a value in each of these widgets, you click a Button widget and run an update query in its onClick event that updates the Titles_Attributes_Join table.
Please also take a look at our sample apps and fork them to check the code if you find any of them helpful for your use case.

I went down that path and used an UPSERT function to handle adding and updating. The problem I have now is how to handle when one gets unchecked and needs to get DELETED.

You want to delete both the record in the table and the Joined table (for many to many) as well?

For example an Admin Assistant (title_id = 1) would have access to Projects Folder (attribute_id = 1), Accounting Folder (attribute_id = 2), and HR Folder (attribute_id = 3). The Join table would haves 3 records - (1, 1), (1, 2), (1,3). And in the Multitree this works great to display. But if I remove say Accounting Folder it should delete the (1,2) row in the join table.

In this case, you could create a query that’ll remove based on what was unchecked. Since they all have a common attribute (Admin Assistant), I assume there should be a way to know before hand.

I kind of feel like this is cheating but it’s working.

DELETE FROM titles_attributes_join 
WHERE title_id = {{}}

INSERT INTO titles_attributes_join (title_id, title_attribute_id) 
{{ => {
	const key =;
	return "('" + key + "'," + "'" + item  + "')"
}).join(",") }}

ON CONFLICT ON CONSTRAINT uq_title_attribute_ids 

It’s definitely cheating :sweat_smile: but it’s quite okay.
I can’t think of a better way right now