Why is DELETE not supported on to-many-association resources in Spring Data REST?
rest, spring-data, spring-data-rest
Solution
I just checked the code and you're right, we're actively rejecting `DELETE` requests for `Map`s and collections. The rationale is as follows:
An association that is of `Map` or collection must never be `null` in the domain model. Translating this into HTTP resources means that the resource will always be available and in the worst case return an empty representation (empty JSON array, or empty JSON object). Accepting a `DELETE` request would logically `null` the relationship in the domain model and thus lead to a state that contradicts the very first assumption.
We generally recommend to simply PUT an empty body with media type `text/uri-list` to the association resource to empty out the associations as that's semantically more correct. Consider it like the difference between truncating and dropping a database table.
If you think that should change and have good reasons that you can back your request with, feel free to open a ticket in our JIRA.
Problem
I am using Spring Data REST. I am trying to unbind a collection association from an entity (item). i.e. - a property of the item is of `List` type. I want to remove all items from that `List`. To do this, I am using the DELETE method: ``` curl -X DELETE …/categories/54ea0bcf27a2fb1b4641083a/fixedParentCategories ``` This gives me a `405 Method not allowed` error code. But, it works for a single valued association (when it is not of `List` type). The documentation clearly lists `DELETE` as a supported method for associations. I'd like to know if there is a way around this. Also, I tried using `PUT` (Content-Type: text/uri-list) with an empty body, and it gives an error about missing request body. Other operations on this association are all working fine - I am able to add items to this collection, etc. My entity looks like this: ``` @Document public class Category { @DBRef(lazy = true) private List<Category> fixedParentCategories; … } ```