Handle maxTTL deserialization in ManifestCollection by handling -1 as None ?

[servufi]

Description:
Implementation of the max_expiry field in ManifestCollection struct assumes it will always hold a valid u64. However, -1 may be returned when no expiration (?) is set? This results in deserialization errors when trying to cast -1 to u64.

Problem:

    // Example call:
    bucket.collections().get_all_scopes(GetAllScopesOptions::default()).await;
    // Output:
    DecodingFailure { ctx: {}, source: Custom { kind: InvalidData, error: Error("invalid value: integer `-1`, expected u64", line: 1, column: 189) } }

    // Caused by couchbase/src/api/collections.rs:
    #[derive(Debug, Deserialize)]
    struct ManifestCollection {
        uid: String,
        name: String,
        #[serde(rename = "maxTTL")]
        max_expiry: u64, // <- This
    }

Workaround couchbase/src/api/collections.rs:

#[derive(Debug, Deserialize)]
struct ManifestCollection {
    uid: String,
    name: String,
    #[serde(rename = "maxTTL", deserialize_with = "deserialize_max_ttl")]
    max_expiry: Option<u64>,  // Option to represent no expiry -1 ?
}

// Custom deserialization function for maxTTL
fn deserialize_max_ttl<'de, D>(deserializer: D) -> Result<Option<u64>, D::Error>
where
    D: serde::Deserializer<'de>,
{
    let value: i64 = serde::Deserialize::deserialize(deserializer)?;
    if value == -1 {
        Ok(None)  // -1 represents no expiry ?
    } else if value >= 0 {
        Ok(Some(value as u64))  // Valid u64 values
    } else {
        Err(serde::de::Error::custom("invalid value for max_expiry"))
    }
}

...

impl CollectionManager {
    ...
    pub async fn get_all_scopes(
        &self,
        options: impl Into<Option<GetAllScopesOptions>>,
    ) -> CouchbaseResult<Vec<ScopeSpec>> {
        ...
        for scope in manifest.scopes {
            let mut collections = vec![];
            for col in scope.collections {
                let expiry_duration = col.max_expiry.map_or(Duration::ZERO, |secs| Duration::from_secs(secs));
                collections.push(CollectionSpec::new(
                    col.name,
                    scope.name.clone(),
                    expiry_duration,
                ))
            }
            scopes.push(ScopeSpec::new(scope.name, collections));
        }
        ...
    }
    ...
}

Worked for me but not sure if something else broke 😆