fix(828): ensuring valid JSON response from REST API

[gabrik]

This PR ensures that the response of the REST plugin is a valid JSON, Closes #828

If a sample has application/json or text/json or text/json5 encoding then we try to convert it to a serde_json::Value if we fail then can be converted to a string via the from_utf8 function then we return its payload as JSON string, otherwise it is encoded as base64 and return as JSON string.
If the sample has a different encoding and can be converted to a string via the from_utf8 function then we return its payload as JSON string , otherwise it is encoded as base64 and return as JSON string.

This is an example of a get with the different cases:

[
    // real json
    {
        "key": "demo/temp/json",
        "value": {
            "hello": "world",
            "this": {
                "is-a": "json"
            }
        },
        "encoding": "application/json",
        "time": "2024-03-14T13:36:57.440128661Z/ff29c02c6c1044c6a1b565c24566b760"
    },
    // empty json
    {
        "key": "demo/temp/empty",
        "value": null,
        "encoding": "application/json",
        "time": "2024-03-14T13:35:31.929630711Z/ff29c02c6c1044c6a1b565c24566b760"
    },
    // text that was inserted as it was a json
    {
        "key": "demo/temp/text",
        "value": "this is a text, but i said it is a json",
        "encoding": "application/json",
        "time": "2024-03-14T13:35:49.283543717Z/ff29c02c6c1044c6a1b565c24566b760"
    },
    // binary, image in this case, that was inserted as json
    {
        "key": "demo/temp/binary",
        "value": "/9j/4AAQSkZJRgABAQAAAAAAAAD/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/wAALCAAgACABAREA/8QAFQABAQAAAAAAAAAAAAAAAAAAAAn/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/9oACAEBAAA/AKpgAAAAP//Z",
        "encoding": "application/json",
        "time": "2024-03-14T13:41:08.952893450Z/ff29c02c6c1044c6a1b565c24566b760"
    },
    // image inserted as image
        {
        "key": "demo/temp/image2",
        "value": "/9j/4AAQSkZJRgABAQAAAAAAAAD/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/wAALCAAgACABAREA/8QAFQABAQAAAAAAAAAAAAAAAAAAAAn/xAAUEAEAAAAAAAAAAAAAAAAAAAAA/9oACAEBAAA/AKpgAAAAP//Z",
        "encoding": "image/jpeg",
        "time": "2024-03-14T13:46:20.142042767Z/ff29c02c6c1044c6a1b565c24566b760"
    }
]

[eclipse-zenoh-bot]

@gabrik If this pull request contains a bugfix or a new feature, then please consider using Closes #ISSUE-NUMBER syntax to link it to an issue.

[eclipse-zenoh-bot]

@gabrik If this pull request contains a bugfix or a new feature, then please consider using Closes #ISSUE-NUMBER syntax to link it to an issue.

[eclipse-zenoh-bot]

@gabrik If this pull request contains a bugfix or a new feature, then please consider using Closes #ISSUE-NUMBER syntax to link it to an issue.

[Mallets]

Why not using the .deserialize()?

[Mallets]

Or even

zenoh/zenoh/src/payload.rs

Line 561 in d808ba2

pub enum StringOrBase64 {

?

[gabrik]

Didn't knew about it

[gabrik]

Updated code to use StringOrBase64::from and then dereferecing to String.

A clone() becomes necessary but should be fine.

[Mallets]

Rust prefers the usage of is_empty() rather than checking if the len() == 0