This completes the rename started in #66136. `[field]` is too generic of
a selector for the forms system to own, and likely to cause naming
collisions with existing components. Therefore it is being renamed to
`[formField]`
This PR makes a number of changes to the metadata API to address design
flaws in the previous API. Some of the changes include:
- Replaces the previous `MetadataKey` and `AggregateMetadataKey` with a
single unified `MetadataKey` that is used for all metadata.
- The new `MetadataKey` is only defined for fields that explicitly set
it in their schema logic
- All metadata now has reducer / aggregate behavior
- The new `MetadataKey` has an option to create a managed key which
wraps the result of its computed aggregate into some other structure
such as a `Resource` or `linkedSignal`
- There are now two APIs to create metadata keys
- `createMetadataKey` for pure computed metadata
- `createManagedMetadataKey` for metadata that manages its computation
internally
Currently we maintain the pathKeys internally, but do not expose them
through the `FieldContext`, this PR updates the `FieldContext` to expose
this property.
This commit introduces an experimental version of a new signal-based forms API for Angular. This new API aims to explore how signals can be leveraged to create a more declarative, intuitive, and reactive way of handling forms.
The primary goals of this new signal-based approach are:
* **Signal-centric Design:** Place signals at the core of the forms experience, enabling a truly reactive programming model for form state and logic.
* **Declarative Logic:** Allow developers to define form behavior, such as validation and conditional fields, declaratively using TypeScript. This moves logic out of the template and into a typed, testable schema.
* **Developer-Owned Data Model:** The library does not maintain a copy of data in a form model, but instead read and write it via a developer-provided `WritableSignal`, eliminating the need for applications to synchronize their data with the form system.
* **Interoperability:** A key design goal is seamless interoperability with existing reactive forms, allowing for incremental adoption.
* **Bridging Template and Reactive Forms:** This exploration hopes to close the gap between template and reactive forms, offering a unified and more powerful approach that combines the best aspects of both.
This initial version of the experimental API includes the core building blocks, such as the `form()` function, `Field` and `FieldState` objects, and a `[control]` directive for binding to UI elements. It also introduces a schema-based system for defining validation, conditional logic, and other form behaviors.
Note: This is an early, experimental API. It is not yet complete and is subject to change based on feedback and further exploration.
Co-authored-by: Kirill Cherkashin <kirts@google.com>
Co-authored-by: Alex Rickabaugh <alxhub@users.noreply.github.com>
Co-authored-by: Leon Senft <leonsenft@users.noreply.github.com>
Co-authored-by: Dylan Hunn <dylhunn@gmail.com>
Co-authored-by: Michael Small <michael-small@users.noreply.github.com>
PR Close#63408
Miles Malerba