org.apache.cayenne

## Class ObjectId

- java.lang.Object
- - org.apache.cayenne.ObjectId

- All Implemented Interfaces:
    Serializable

      public class ObjectId
      extends Object
      implements Serializable

  A portable global identifier for persistent objects. ObjectId can be temporary (used for transient or new uncommitted objects) or permanent (used for objects that have been already stored in DB). A temporary ObjectId stores object entity name and a pseudo-unique binary key; permanent id stores a map of values from an external persistent store (aka "primary key").
  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `protected String` | `entityName`
    `protected byte[]` | `key`
    `protected Map<String,Object>` | `objectIdKeys`
    `protected Map<String,Object>` | `replacementIdMap`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `ObjectId(String entityName)` Creates a TEMPORARY ObjectId.
    `ObjectId(String entityName, byte[] key)` Creates a TEMPORARY id with a specified entity name and a binary key.
    `ObjectId(String entityName, Map<String,?> idMap)` Creates a portable permanent ObjectId as a compound primary key.
    `ObjectId(String entityName, String key, int value)` Creates a portable permanent ObjectId.
    `ObjectId(String entityName, String key, Object value)` Creates a portable permanent ObjectId.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `ObjectId` | `createReplacementId()` Creates and returns a replacement ObjectId.
    `boolean` | `equals(Object object)`
    `String` | `getEntityName()`
    `Map<String,Object>` | `getIdSnapshot()` Returns an unmodifiable Map of persistent id values, essentially a primary key map.
    `byte[]` | `getKey()` Get the binary temporary object id.
    `Map<String,Object>` | `getReplacementIdMap()` Returns a non-null mutable map that can be used to append replacement id values.
    `int` | `hashCode()`
    `boolean` | `isReplacementIdAttached()` Returns true if there is full or partial replacement id attached to this id.
    `boolean` | `isTemporary()` Is this is temporary object id (used for objects which are not yet persisted to the data store).
    `String` | `toString()` A standard toString method used for debugging.

    - ### Methods inherited from class java.lang.Object

      `clone, finalize, getClass, notify, notifyAll, wait, wait, wait`

- - ### Field Detail

    - #### entityName

          protected String entityName

    - #### objectIdKeys

          protected Map<String,Object> objectIdKeys

    - #### key

          protected byte[] key

    - #### replacementIdMap

          protected Map<String,Object> replacementIdMap

  - ### Constructor Detail

    - #### ObjectId

          public ObjectId(String entityName)

      Creates a TEMPORARY ObjectId. Assigns a generated unique key.
      Since:
        1.2

    - #### ObjectId

          public ObjectId(String entityName,
                          byte[] key)

      Creates a TEMPORARY id with a specified entity name and a binary key. It is a caller responsibility to provide a globally unique binary key.
      Since:
        1.2

    - #### ObjectId

          public ObjectId(String entityName,
                          String key,
                          int value)

      Creates a portable permanent ObjectId.
      Parameters:
        `entityName` - The entity name which this object id is for
        `key` - A key describing this object id, usually the attribute name for the primary key
        `value` - The unique value for this object id
      Since:
        1.2

    - #### ObjectId

          public ObjectId(String entityName,
                          String key,
                          Object value)

      Creates a portable permanent ObjectId.
      Parameters:
        `entityName` - The entity name which this object id is for
        `key` - A key describing this object id, usually the attribute name for the primary key
        `value` - The unique value for this object id
      Since:
        1.2

    - #### ObjectId

          public ObjectId(String entityName,
                          Map<String,?> idMap)

      Creates a portable permanent ObjectId as a compound primary key.
      Parameters:
        `entityName` - The entity name which this object id is for
        `idMap` - Keys are usually the attribute names for each part of the primary key. Values are unique when taken as a whole.
      Since:
        1.2

  - ### Method Detail

    - #### isTemporary

          public boolean isTemporary()

      Is this is temporary object id (used for objects which are not yet persisted to the data store).

    - #### getEntityName

          public String getEntityName()

      Since:
        1.2

    - #### getKey

          public byte[] getKey()

      Get the binary temporary object id. Null if this object id is permanent (persisted to the data store).

    - #### getIdSnapshot

          public Map<String,Object> getIdSnapshot()

      Returns an unmodifiable Map of persistent id values, essentially a primary key map. For temporary id returns replacement id, if it was already created. Otherwise returns an empty map.

    - #### equals

          public boolean equals(Object object)

      Overrides:
        `equals` in class `Object`

    - #### hashCode

          public int hashCode()

      Overrides:
        `hashCode` in class `Object`

    - #### getReplacementIdMap

          public Map<String,Object> getReplacementIdMap()

      Returns a non-null mutable map that can be used to append replacement id values. This allows to incrementally build a replacement GlobalID.
      Since:
        1.2

    - #### createReplacementId

          public ObjectId createReplacementId()

      Creates and returns a replacement ObjectId. No validation of ID is done.
      Since:
        1.2

    - #### isReplacementIdAttached

          public boolean isReplacementIdAttached()

      Returns true if there is full or partial replacement id attached to this id. This method is preferrable to "!getReplacementIdMap().isEmpty()" as it avoids unneeded replacement id map creation.

    - #### toString

          public String toString()

      A standard toString method used for debugging. It is guaranteed to produce the same string if two ObjectIds are equal.
      Overrides:
        `toString` in class `Object`

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