Package org.dspace.app.rest.projection

Interface Projection

All Known Implementing Classes:
AbstractProjection, CompositeProjection, DefaultProjection, EmbedRelsProjection, FullProjection, SpecificLevelProjection
public interface Projection
A pluggable, uniquely-named Component that provides a way to change how a domain object is represented, at one or more points in its lifecycle on the way to its being exposed via the REST API.

The object lifecycle

While fulfilling a typical REST request, a DSpace domain object takes three major forms, in order:

What a projection can modify, and when

A Projection implementation is capable of adding to or omitting information from the object in any of these forms, at the following points in time:

How a projection is chosen

See Utils.obtainProjection().

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    static final Projection
    DEFAULT
    The default projection.

  • Method Summary

    Modifier and Type
    Method
    Description
    boolean
    allowEmbedding(HALResource<? extends RestAddressableModel> halResource, LinkRest linkRest, org.springframework.hateoas.Link... oldLinks)
    Tells whether this projection permits the embedding of a particular embeddable subresource.
    boolean
    allowLinking(HALResource halResource, LinkRest linkRest)
    Tells whether this projection permits the linking of a particular linkable subresource.
    String
    getName()
    Gets the projection name.
    org.springframework.data.domain.PageRequest
    getPagingOptions(String rel, HALResource<? extends RestAddressableModel> resource, org.springframework.hateoas.Link... oldLinks)
    This method will return the PageRequest object for a specific given rel
    <T> T
    transformModel(T modelObject)
    Transforms the original model object (e.g.
    <T extends HALResource>
    T
    transformResource(T halResource)
    Transforms the resource object after it has been constructed and any constructor or annotation-based links and embeds have been added.
    <T extends RestModel>
    T
    transformRest(T restObject)
    Transforms the rest object after it was converted from a model object.

  • Field Details

    • DEFAULT

      static final Projection DEFAULT
      The default projection.

  • Method Details

    • getName

      String getName()
      Gets the projection name.
      Returns:
      the name, which is a unique alphanumeric string.

    • transformModel

      <T> T transformModel(T modelObject)
      Transforms the original model object (e.g. JPA entity) before conversion to a RestModel. This is a good place to omit data for certain properties that should not be included in the object's representation as a HALResource. Omitting these properties early helps to prevent unnecessary database calls for lazy-loaded properties that are unwanted for the projection.
      Type Parameters:
      T - the return type, which must be the same type as the given model object.
      Parameters:
      modelObject - the original model object, which may be of any type.
      Returns:
      the transformed model object, or the original, if the projection does not modify it.

    • transformRest

      <T extends RestModel> T transformRest(T restObject)
      Transforms the rest object after it was converted from a model object. This may add data to, or omit data from the rest representation of the object.
      Type Parameters:
      T - the return type, which must be of the same type as the given rest object.
      Parameters:
      restObject - the rest object.
      Returns:
      the transformed rest object, or the original, if the projection does not modify it.

    • transformResource

      <T extends HALResource> T transformResource(T halResource)
      Transforms the resource object after it has been constructed and any constructor or annotation-based links and embeds have been added. This may add data to, or omit data from the HAL resource representation of the object.
      Type Parameters:
      T - the return type, which must be of the same type as the given resource object.
      Parameters:
      halResource - the resource object.
      Returns:
      the transformed resource object, or the original, if the projection does not modify it.

    • allowEmbedding

      boolean allowEmbedding(HALResource<? extends RestAddressableModel> halResource, LinkRest linkRest, org.springframework.hateoas.Link... oldLinks)
      Tells whether this projection permits the embedding of a particular embeddable subresource. This gives the projection an opportunity to opt in to to certain embeds, by returning true. Note: If this method returns true for a given subresource, it will be automatically linked regardless of what allowLinking(HALResource, LinkRest) returns.
      Parameters:
      halResource - the resource from which the embed may or may not be made.
      linkRest - the LinkRest annotation through which the related resource was discovered on the rest object.
      oldLinks - The previously traversed links
      Returns:
      true if allowed, false otherwise.

    • allowLinking

      boolean allowLinking(HALResource halResource, LinkRest linkRest)
      Tells whether this projection permits the linking of a particular linkable subresource. This gives the projection an opportunity to opt in to to certain links, by returning true. Note: If allowEmbedding(HALResource, LinkRest, Link...) returns true for a given subresource, it will be automatically linked regardless of what this method returns.
      Parameters:
      halResource - the resource from which the link may or may not be made.
      linkRest - the LinkRest annotation through which the related resource was discovered on the rest object.
      Returns:
      true if allowed, false otherwise.

    • getPagingOptions

      org.springframework.data.domain.PageRequest getPagingOptions(String rel, HALResource<? extends RestAddressableModel> resource, org.springframework.hateoas.Link... oldLinks)
      This method will return the PageRequest object for a specific given rel
      Parameters:
      rel - The rel for which the PageRequest object will be made
      resource - the resource from which the embed may or may not be made.
      oldLinks - The previously traversed links
      Returns:
      The PageRequest object for the given rel