how to generate json schema from serde_json::value::Value?

[clojurians-org]

i want to generate json schema from dynamic json value.
i don't know whether schemars support this function.

    let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;
    let v: Value = serde_json::from_str(data)? ;

[ahl]

Pretty sure this library doesn't handle that case. It's great for Type -> JsonSchema, but you're deriving the schema from the data rather than from the type. That said, it would be pretty straightforward to build a function to extract a schema from the Value.

[GREsau]

This functionality isn't currently implemented, but I would like to do something like this. And actually I'd prefer to widen it to allow generating a schema from an instance any type that implements serde::Serialize (which includes serde_json::value::Value). Then you can get a schema from any value that can be serialized, even if it doesn't implement JsonSchema. And there would be more type information available than if it was done via a Value, allowing a richer schema.

[GREsau]

This will be possible in the next version - this code:

let data = r#"
        {
            "name": "John Doe",
            "age": 43,
            "phones": [
                "+44 1234567",
                "+44 2345678"
            ]
        }"#;
let v: serde_json::Value = serde_json::from_str(data)?;
let schema = schema_for_value!(v);
println!("{}", serde_json::to_string_pretty(&schema)?);

Produces this schema:

{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "examples": [
    {
      "age": 43,
      "name": "John Doe",
      "phones": [
        "+44 1234567",
        "+44 2345678"
      ]
    }
  ],
  "type": "object",
  "properties": {
    "age": {
      "type": "integer"
    },
    "name": {
      "type": "string"
    },
    "phones": {
      "type": "array",
      "items": {
        "type": "string"
      }
    }
  }
}

[GREsau]

schema_for_value!(...) won't be limited to serde_json::Values - as I said in my earlier comment, any type that implements serde::Serialize can have a schema generated from a value, e.g. from_value.rs / from_value.schema.json

[GREsau]

Implemented and published! https://crates.io/crates/schemars/0.8.2

[jacobsvante]

Nice work @GREsau 😀👍🏻