Error handling

[MarinPostma]

This pr implements the error handling for meilisearch.

Rather than grouping errors by types, this implementation groups them by scope, each scope enclosing errors from a scope further down, or new errors within this scope. This makes the tracking of the origins of errors easier , and error handling easier at the module level.

All errors that are eventually returned to the user implement the Into<ResponseError> trait. ReponseError in turn implements the ErrorCode trait from meilisearch-error.

Some new errors have been introduced with the new engine for which we haven't defined error codes yet. It has been decided with @gmourier that those would return the internal-error code until the correct error code is specified.

[irevoire]

best PR I've seen so far 😎

[curquiza]

Can you return a content-type: application/json when returning an error?

[curquiza]

When pushing a badly formatted JSON document (for example the extra coma at the end of the line) I got a bad_request in v0.20.0 and now an internal. Can we change this?

[curquiza]

Can we remove the todo from the update answer?

[curquiza]

Related to my previous comment: missing primary key has already an error code -> https://docs.meilisearch.com/errors/#missing_primary_key

[MarinPostma]

@curquiza yeah sorry this part is unrelated to error codes, i just forgot to change the error type for updates 🤦

[curquiza]

Another feedback. Before there were two errors:

• missing_primary_key -> there is no document in MeiliSearch, you try to insert document, but MeilISearch cannot find the primary key.
• missing_document_id -> there is already a defined primary key but the documents you try to push do not contain it.

Now, I only get the missing_primay_key error when doing my tests.

[curquiza]

When trying:

{
    "q": "",
    "filters": "genre = fantasy"
}

I get an internal error, but an error code already exists for this: bad_request

[MarinPostma]

Another feedback. Before there were two errors:

missing_primary_key -> there is no document in MeiliSearch, you try to insert document, but MeilISearch cannot find the primary key.
missing_document_id -> there is already a defined primary key but the documents you try to push do not contain it.
Now, I only get the missing_primay_key error when doing my tests.

I'm not the one returning this error, milli is, @ManyTheFish @Kerollmops, this one is one you guys ;)

@curquiza I think the rest is fixed.

[curquiza]

Can we change the message to the v0.20 one?

Transplant

MeiliSearch v0.20

[curquiza]

Same for index not found:
Transplant

Meilisearch v0.20

[irevoire]

When looking for a non-existing update, don't get the same message as before:
Meilisearch: "Update 4 not found"
Transplant: "error with update: update 4 doesn't exist."

---

When doing a search with a bad field name the message also slightly vary:
Meilisearch:

"Invalid JSON: unknown field `truc`, expected one of `q`, `offset`, `limit`, `attributesToRetrieve`, `attributesToCrop`, `cropLength`, `attributesToHighlight`, `filters`, `matches`, `facetFilters`, `facetsDistribution` at line 1 column 22"

Transplant:

"Json deserialize error: unknown field `truc`, expected one of `q`, `offset`, `limit`, `attributesToRetrieve`, `attributesToCrop`, `cropLength`, `attributesToHighlight`, `matches`, `filter`, `facetDistributions` at line 1 column 22"

Feel free to close this comment if this is not an issue!

[curquiza]

Checked with @MarinPostma! Issues will be open for the message errors and will be fixed for the v0.21.0

[MarinPostma]

bors merge

[bors]

Build succeeded:

• Cargo check on Windows
• Run Clippy
• Tests on macos-latest
• Tests on ubuntu-18.04