移除REST资源集合中的_embedded及REST端点链接规范咨询

Great questions! Let's break this down step by step based on HAL specifications and Spring HATEOAS behavior:

• First, why is _embedded present? This is a core requirement of the HAL (Hypertext Application Language) specification. HAL uses _embedded to wrap collection items, clearly separating the resource's core data from metadata like links (stored in _links). Your current response is fully compliant with HAL standards.
• Can you remove it? Yes—but doing so means your response will no longer be valid HAL. If your client doesn't rely on HAL's structure (e.g., it's a custom client you control), you can adjust your controller to return a plain list of resources instead of wrapping them in Resources<>.

Here's how to modify your controller to skip the _embedded wrapper:

@GetMapping 
public ResponseEntity<List<Resource<CharacterDescription>>> getAllCharacterDescriptions() { 
    List<Resource<CharacterDescription>> characters = repository.findAll()
        .stream()
        .map(character -> { 
            Link characterLink = linkTo(methodOn(CharacterDescriptionController.class)
                .getCharacterDescription(character.getCharacterId()))
                .withSelfRel(); 
            return new Resource<>(character, characterLink); 
        })
        .collect(Collectors.toList()); 
    // Note: This returns a plain array without top-level _links.self
    // If you still need the top-level self link, create a custom DTO to hold both the list and link
    return ResponseEntity.ok(characters); 
}

This will output a direct JSON array of character resources, but keep in mind: HAL-aware clients will fail to parse this correctly, as it deviates from the standard.

• Self link is mandatory per HAL: Every resource (single or collection) must include a self link pointing to its own URL. Your current single-resource responses already do this, which is correct.
• Parent link to /characters is optional: HAL doesn't require this, but it's a common practice to improve API discoverability. Adding it lets clients easily navigate back to the full collection if needed.

Here's an example of adding a parent link to your single-resource endpoint:

@GetMapping("/{id}")
public ResponseEntity<Resource<CharacterDescription>> getCharacterDescription(@PathVariable Long id) {
    CharacterDescription character = repository.findById(id)
        .orElseThrow(() -> new NotFoundException("Character not found"));
    
    Link selfLink = linkTo(methodOn(CharacterDescriptionController.class)
        .getCharacterDescription(id))
        .withSelfRel();
    // Add a link to the parent collection
    Link collectionLink = linkTo(methodOn(CharacterDescriptionController.class)
        .getAllCharacterDescriptions())
        .withRel("characters"); // Use a consistent rel name (e.g., "collection" or "parent" also work)
    
    Resource<CharacterDescription> resource = new Resource<>(character, selfLink, collectionLink);
    return ResponseEntity.ok(resource);
}

If you don't need this navigability, omitting the parent link is still fully compliant with HAL.

内容的提问来源于stack exchange，提问作者LiamRyan