**NOTE: This is based on, and should be merged alongside,
https://github.com/bevyengine/bevy/pull/15482.** I'll leave this in
draft until that PR is merged.
# Objective
Equivalent of https://github.com/bevyengine/bevy/pull/15482 but for
serialization. See that issue for the motivation.
Also part of this tracking issue:
https://github.com/bevyengine/bevy/issues/15518
This PR is non-breaking, just like the deserializer PR (because the new
type parameter `P` has a default `P = ()`).
## Solution
Identical solution to the deserializer PR.
## Testing
Added unit tests and a very comprehensive doc test outlining a clear
example and use case.
# Objective
- fix https://github.com/bevyengine/bevy/issues/15623
## Solution
- Checking field length of tuple struct before ser/der
## Testing
- CI should pass
## Migration Guide
- Reflection now will serialize and deserialize tuple struct with single
field as newtype struct. Consider this code.
```rs
#[derive(Reflect, Serialize)]
struct Test(usize);
let reflect = Test(3);
let serializer = TypedReflectSerializer::new(reflect.as_partial_reflect(), ®istry);
return serde_json::to_string(&serializer)
```
Old behavior will return `["3"]`. New behavior will return `"3"`. If you
were relying on old behavior you need to update your logic. Especially
with `serde_json`. `ron` doesn't affect from this.
# Objective
Reflection serialization can be difficult to debug. A lot of times a
type fails to be serialized and the user is left wondering where that
type came from.
This is most often encountered with Bevy's scenes. Attempting to
serialize all resources in the world will fail because some resources
can't be serialized.
For example, users will often get complaints about `bevy_utils::Instant`
not registering `ReflectSerialize`. Well, `Instant` can't be serialized,
so the only other option is to exclude the resource that contains it.
But what resource contains it? This is where reflection serialization
can get a little tricky (it's `Time<Real>` btw).
## Solution
Add the `debug_stack` feature to `bevy_reflect`. When enabled, the
reflection serializers and deserializers will keep track of the current
type stack. And this stack will be used in error messages to help with
debugging.
Now, if we unknowingly try to serialize `Time<Real>`, we'll get the
following error:
```
type `bevy_utils::Instant` did not register the `ReflectSerialize` type data. For certain types, this may need to be registered manually using `register_type_data` (stack: `bevy_time::time::Time<bevy_time::real::Real>` -> `bevy_time::real::Real` -> `bevy_utils::Instant`)
```
### Implementation
This makes use of `thread_local!` to manage an internal `TypeInfoStack`
which holds a stack of `&'static TypeInfo`. We push to the stack before
a type is (de)serialized and pop from the stack afterwards.
Using a thread-local should be fine since we know two (de)serializers
can't be running at the same time (and if they're running on separate
threads, then we're still good).
The only potential issue would be if a user went through one of the
sub-serializers, like `StructSerializer`. However, I don't think many
users are going through these types (I don't even know if we necessarily
want to keep those public either, but we'll save that for a different
PR). Additionally, this is just a debug feature that only affects error
messages, so it wouldn't have any drastically negative effect. It would
just result in the stack not being cleared properly if there were any
errors.
Lastly, this is not the most performant implementation since we now
fetch the `TypeInfo` an extra time. But I figured that for a debug tool,
it wouldn't matter too much.
### Feature
This also adds a `debug` feature, which enables the `debug_stack`
feature.
I added it because I think we may want to potentially add more debug
tools in the future, and this gives us a good framework for adding
those. Users who want all debug features, present and future, can just
set `debug`. If they only want this feature, then they can just use
`debug_stack`.
I also made the `debug` feature default to help capture the widest
audience (i.e. the users who want this feature but don't know they do).
However, if we think it's better as a non-default feature, I can change
it!
And if there's any bikeshedding around the name `debug_stack`, let me
know!
## Testing
Run the following command:
```
cargo test --package bevy_reflect --features debug_stack
```
---
## Changelog
- Added the `debug` and `debug_stack` features to `bevy_reflect`
- Updated the error messages returned by the reflection serializers and
deserializers to include more contextual information when the
`debug_stack` or `debug` feature is enabled
# Objective
The `ser` and `de` modules in `bevy_reflect/serde` are very long and
difficult to navigate.
## Solution
Refactor both modules into many smaller modules that each have a single
primary focus (i.e. a `structs` module that only handles struct
serialization/deserialization).
I chose to keep the `ser` and `de` modules separate. We could have
instead broken it up kind (e.g. lists, maps, etc.), but I think this is
a little cleaner. Serialization and deserialization, while related, can
be very different. So keeping them separated makes sense for
organizational purposes.
That being said, if people disagree and think we should structure this a
different way, I am open to changing it.
Note that this PR's changes are mainly structural. There are a few
places I refactored code to reduce duplication and to make things a bit
cleaner, but these are largely cosmetic and shouldn't have any impact on
behavior.
### Other Details
This PR also hides a lot of the internal logic from being exported.
These were originally public, but it's unlikely they really saw any use
outside of these modules. In fact, you don't really gain anything by
using them outside of this module either.
By privatizing these fields and items, we also set ourselves up for more
easily changing internal logic around without involving a breaking
change.
I also chose not to mess around with tests since that would really blow
up the diff haha.
## Testing
You can test locally by running:
```
cargo test --package bevy_reflect --all-features
```
---
## Migration Guide
The fields on `ReflectSerializer` and `TypedReflectSerializer` are now
private. To instantiate, the corresponding constructor must be used:
```rust
// BEFORE
let serializer = ReflectSerializer {
value: &my_value,
registry: &type_registry,
};
// AFTER
let serializer = ReflectSerializer::new(&my_value, &type_registry);
```
Additionally, the following types are no longer public:
- `ArraySerializer`
- `EnumSerializer`
- `ListSerializer`
- `MapSerializer`
- `ReflectValueSerializer` (fully removed)
- `StructSerializer`
- `TupleSerializer`
- `TupleStructSerializer`
As well as the following traits:
- `DeserializeValue` (fully removed)
