RFC created: 1970/01/01
Last updated: unknown
# Data Service
- Data-dependent Lightning Web Components (LWC) are fast at runtime.
- LWC development and lifecycle are simple. Much simpler than Aura's.
- Aura and LWC data services are compatible.
- Cache and view coherency is enforced.
- It's all data from LWC's perspective.
- Salesforce metadata and data are data.
- Non-Salesforce metadata and data are data.
- Only LWC metadata (eg module defs) is metadata.
- All data mutates over time yet a given snapshot of data is immutable.
- A component receiving data does not own that data. It is comparable to a component receiving props does not own the props.
- In the rare case where handling changing data over time is sufficiently costly (in runtime, complexity, etc) then the application may choose to reload/rebootstrap itself. The typical example is a change in locale and language; these impact all labels, formatting, data, etc. A reboot of the application is the simplest way to handle the change.
- The Data Service allows pluggable logic to manage domains of data.
- In this regard the Data Service is conceptually a directory of underlying data services.
- Each data domain defines its own verbs (eg CRUD) and behavior.
- A data domain may choose to support progressive loading of data.
- Each data domain defines its caching and invalidation strategy.
# Component Integration
- Loading data is expressed declaratively by a component.
- The expression may provide static values, reference props or getters.
- Props are monitored for changes. Monitoring getters is TBD.
- Data declarations may be accessed at compile time and may influence compiled output.
- Data is bound to decorated field or function.
- Component data declaration's comes in two flavors:
- A root query: the query is sufficient to be resolved by a data service.
- A fragment query: the query is insufficient. It must be rolled up to a root query.