Error updating group repository metadata input contained no data

Taking the initial example of users having addresses imagine those addresses are set up to belong to a country.If you want to allow users to bulk edit all addresses that belong to a single country, you can do so by changing the preload query: Optimistic locking works by keeping a "version" counter for each record; this counter gets incremented each time a modification is made to a record.

Changesets allow working with both kinds of data: Ecto changesets provide both validations and constraints which are ultimately turned into errors in case something goes wrong.

If you need deletion, it is often preferred to add a separate boolean virtual field to the changeset function that will allow you to manually mark it for deletion, as in the example below: This means that when working with changesets that are not meant to be persisted to the database, such as schemaless changesets, you may need to explicitly set the action to one specific value.

Frameworks such as Phoenix use the action value to define how HTML forms should act.

Assuming we have a with the list of comments given, and correctly insert the new comment to the database.

Note, however, Ecto is doing a lot of work just to figure out something we knew since the beginning, which is that there is only one new comment.

Changesets do not support this type of constraints.