Required key
A required key is a named field, property, parameter, flag, or input whose presence or value is mandatory for validity or operation.
The Design of Web APIs, Second Edition
A required flag is a data-model setting that indicates whether a property must be present in an operation's returned data.
- How it is used
- Guides API data modeling by distinguishing consumer-supplied values from implementation-returned values.
- How deep it goes
- Explains property-level decisions across resources, nested objects, read responses, creation inputs, JSON Schema, and response headers.
- Examples
- Uses product catalog models, supplier properties, product creation inputs, read responses, and a required Location response header.
- What you can do after
- Apply it via JSON Schema and OpenAPI to describe required inputs, guaranteed outputs, and always-returned response headers.
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React in Depth
A required prop is a component input that must be supplied for the component to function correctly.
- How it is used
- Defines component input contracts by distinguishing indispensable properties from optional behavior and defaults.
- How deep it goes
- Explains declaration, selective utility typing, runtime validation, defaults, and missing-property failure modes without descending into React internals.
- Examples
- Uses typed inputs, native button handlers, a hover-button utility, and a car component with required make and model.
- What you can do after
- Build it from scratch by declaring required inputs with TypeScript or PropTypes and selectively preserving existing component definitions.
Modern Angular
A required input is an Angular input declaration that requires a parent component to provide a value and enables compile-time diagnostics when the value is omitted.
- How it is used
- Marks Angular component inputs that parent templates must provide.
- How deep it goes
- Contrasts runtime validation with a concrete declaration and compile-time template diagnostic, without exploring compiler internals.
- Examples
- Uses ProjectCardComponent and its required projectId input as the concrete implementation example.
- What you can do after
- Apply it via Angular input declarations to catch omitted parent bindings in the editor.
Related concepts
- inputconfigures · An input is a value, information, or signal supplied to a system, computation, or interface for processing or to influence its behavior.
- attributeconfigures · An attribute is a named property, value, or piece of information associated with an entity, object, or program element.
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