Error validating check constraint
In cases like above, when you want to work only on a single entry, it is much easier to simply work on the associated directly.
For example, we could instead set the is a good fit.
By moving constraints to the database, we also provide a safe, correct and data-race free means of checking the user input.
Some databases support deferred constraints, i.e., constraints which are checked at the end of the transaction rather than at the end of each statement.
The difference between them is that most validations can be executed without a need to interact with the database and, therefore, are always executed before attempting to insert or update the entry in the database.
Some validations may happen against the database but they are inherently unsafe. On the other hand, constraints rely on the database and are always safe.
When using any of those APIs, you may run into situations where Ecto sees data is being replaced.
Let's discuss some of this extra functionality.
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.
Imagine we get the data in this format: is a great fit.
It will automatically remove any tag not given and properly associate all of the given tags with the post.