minjinja does not seem to support serde_json arbitrary-precision number types

[janlugt]

I encountered an following issue while reading some JSON from disk, loading it into a serde_json::Value, and trying to create a minijinja context out of it:

let value: serde_json::Value = serde_json::from_str("{\"x\": 42}").unwrap();
println!("value = {}", value.to_string());
let string = serde_json::ser::to_string(&value).unwrap();
println!("string = {}", string);
let context = minijinja::Value::from_serialize(value);
println!("context = {}", context);

This gives the following output:

value = {"x":42}
string = {"x":42}
context = {"x": {"$serde_json::private::Number": "42"}}

I would expect the minijinja::Value to just contain 42 again. If I read the JSON as a specific rust struct, everything works, since in that case the arbitrary-precision number is not used.

Am I holding it wrong, is this expected behavior, or is it a bug?

[mitsuhiko]

This is a serde bug/limitation. I filed an issue a long time ago in the serde repo about it: serde-rs/serde#1463

Not much I can do here :(

What you could do is walk through the serde_json::Value and reconstruct a Jinja value without going via the serde system.

[janlugt]

Thanks! If I serialize to a struct first, things work, since specific number types are known, so that's what I'll do.