[REQ] [rust] map `format: date` to `chrono::naive::NaiveDate` for `rust-server` generator

[seiyab]

Is your feature request related to a problem? Please describe.

According OpenAPI Specification, format: date for type: string is As defined by full-date - RFC3339.
That is defined as date-fullyear "-" date-month "-" date-mday (RFC3339), like 2021-06-15.
So it doesn't have time and timezone information.

However, rust-server generator maps format: date to chrono::DateTime::<chrono::Utc>, that has time and timezone information.
We are forced to add provisional time like 00:00:00 and timezone like Utc to make dates to be chrono::DateTime::<chrono::Utc>.

Describe the solution you'd like

Adding an option to mapformat: date to chrono::naive::NaiveDate.
Though I think the current behavior is not desire, changing the API causes serious backward incompatibility. It should be added as opt-in approach.
I think NaiveDate is more appropriate than chrono::Date since full-date doesn't have a timezone information.

Describe alternatives you've considered

I don't have any other ideas.

Additional context

Nothing.
I'll add information if community / maintainers need more description.

[richardwhiuk]

Agree that https://docs.rs/chrono/0.4.19/chrono/naive/struct.NaiveDate.html seems like a sensible mapping.

[seiyab]

I found that the current implementation also causes bugs.
Values with format: date are serialized as date-time (e.g. 2021-06-17T22:10:00Z) defined in RFC3339 rather than full-date (e.g. 2021-06-17).
Deserialization might also have a similar problem.
Should we add an option as a new feature, or fix as a Bug?

We might be able to handle them as separate issues.
Say, one is using NaiveDate as schema, and the other is fix the serialization / deserialization problem.

[farazfazli]

On a related note, I noticed that the generated example client code (using rust-server, under examples/client/main.rs) for format: date-time does not compile due to invalid syntax, and I had to manually add parse_from_rfc3339 and turn the generated code into a string to be able to get a Result<DateTime<FixedOffset>> and then unwrap that and convert it into() a DateTime<Utc>.

OpenAPI v3.0.3 spec:

schema:
  type: string
  format: date-time
example: "2022-04-01T08:00:00-04:00"

schema:
  type: string
  format: date-time
example: "2022-04-01T09:00:00-04:00"

Generated:

let result = rt.block_on(client.example_get(
    serde_json::from_str::<uuid::Uuid>(r#"14874e81-634e-46bd-81ac-5e9d63df8b73"#).expect("Failed to parse JSON example"),
    2022-04-01T08:00:00-04:00,
    2022-04-01T09:00:00-04:00
));

Should be:

let result = rt.block_on(client.example_get(
    serde_json::from_str::<uuid::Uuid>(r#"14874e81-634e-46bd-81ac-5e9d63df8b73"#)
        .expect("Failed to parse JSON example"),
    DateTime::parse_from_rfc3339("2022-04-01T08:00:00-04:00")
        .unwrap()
        .into(),
    DateTime::parse_from_rfc3339("2022-04-01T09:00:00-04:00")
        .unwrap()
        .into(),
));

@richardwhiuk Please let me know if you'd like me to open an issue for this. The generated Rust code is really nice overall aside from this small issue I came across.