javax.jdo

## Interface FetchGroup

-     public interface FetchGroup

  FetchGroup represents a named fetch group for a specific class or interface. A fetch group instance identifies the name of the class or interface, the list of members (fields or properties) to be fetched when the fetch group is active, and the recursion depth for each member.

  Fetch groups are updated using methods on this interface. An instance of a class implementing this interface can be obtained from `PersistenceManager.getFetchGroup(java.lang.Class, java.lang.String)` or `PersistenceManagerFactory.getFetchGroup(java.lang.Class, java.lang.String)`.

  A FetchGroup can be unscoped or can be in one of two scopes (the `PersistenceManager` or the `PersistenceManagerFactory` scope). Unscoped FetchGroups do not affect any behavior. A FetchGroup in PersistenceManager scope hides the corresponding FetchGroup in the PersistenceManagerFactory scope.

  - When a FetchGroup is obtained via `PersistenceManager.getFetchGroup(java.lang.Class, java.lang.String)`, it is immediately in scope of its `PersistenceManager`. Subsequent modifications of the FetchGroup immediately affect `FetchPlan`s that contain the `FetchGroup`.
  - When a FetchGroup is obtained via `PersistenceManagerFactory.getFetchGroup(java.lang.Class, java.lang.String)`, it is unscoped.
  - When a FetchGroup is added to the set of active FetchGroups via `PersistenceManagerFactory.addFetchGroups(javax.jdo.FetchGroup...)`, it is put in scope of the `PersistenceManagerFactory`.
  - When a FetchGroup is removed from the set of active FetchGroups via `PersistenceManagerFactory.removeFetchGroups(javax.jdo.FetchGroup...)`, `PersistenceManagerFactory.removeAllFetchGroups()`, or replaced via `PersistenceManagerFactory.addFetchGroups(javax.jdo.FetchGroup...)`, it is unscoped.
  Since:
    2.2
  Version:
    2.2

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static String` | `ALL` For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls.
    `static String` | `BASIC` For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls.
    `static String` | `DEFAULT` For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls.
    `static String` | `MULTIVALUED` For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls.
    `static String` | `RELATIONSHIP` For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls.

  - ### Method Summary

    All Methods Instance Methods Abstract Methods
    Modifier and Type | Method and Description
    --- | ---
    `FetchGroup` | `addCategory(String categoryName)` Add the members (fields or properties) of the named category to the set of members in this FetchGroup.
    `FetchGroup` | `addMember(String memberName)` Add the member (field or property) to the set of members in this FetchGroup.
    `FetchGroup` | `addMembers(String... memberNames)` Add the member (field or property) to the set of members in this FetchGroup.
    `boolean` | `equals(Object other)` Return whether this instance is equal to the other.
    `Set` | `getMembers()` Return an immutable Set of String containing the names of all members.
    `String` | `getName()` Get the name of this FetchGroup.
    `boolean` | `getPostLoad()` Get the post-load property of this FetchGroup.
    `int` | `getRecursionDepth(String memberName)` Get the recursion-depth for this member.
    `Class` | `getType()` Get the persistent type (class or interface) of this FetchGroup.
    `int` | `hashCode()` Return the hashCode for this instance.
    `boolean` | `isUnmodifiable()` Return whether this FetchGroup is unmodifiable.
    `FetchGroup` | `removeCategory(String categoryName)` Remove the members (fields or properties) of the named category from the set of members in this FetchGroup.
    `FetchGroup` | `removeMember(String memberName)` Remove the member (field or property) from the set of members in this FetchGroup.
    `FetchGroup` | `removeMembers(String... memberNames)` Remove the member (field or property) from the set of members in this FetchGroup.
    `FetchGroup` | `setPostLoad(boolean postLoad)` Set the post-load property of this FetchGroup.
    `FetchGroup` | `setRecursionDepth(String memberName, int recursionDepth)` Set the recursion-depth for this member.
    `FetchGroup` | `setUnmodifiable()` Make this FetchGroup unmodifiable.

- - ### Field Detail

    - #### DEFAULT

          static final String DEFAULT

      For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls. This category includes members defined in the default fetch group in xml or annotations. Redefining the default fetch group via the API does not affect the members defined by this category.

      Using this category also sets the fetch-depth for the members in the default fetch group.

      Since:
        2.2
      See Also:
        Constant Field Values

    - #### RELATIONSHIP

          static final String RELATIONSHIP

      For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls. This category includes members of all relationship types.
      Since:
        2.2
      See Also:
        Constant Field Values

    - #### MULTIVALUED

          static final String MULTIVALUED

      For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls. This category includes members of all multi-valued types, including Collection, array, and Map types of basic and relationship types.
      Since:
        2.2
      See Also:
        Constant Field Values

    - #### BASIC

          static final String BASIC

      For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls. This category includes members of all primitive and immutable object class types as defined in section 6.4 of the specification, including String, Locale, Currency, BigDecimal, and BigInteger; as well as Date and its jdbc subtypes and Enum types.
      Since:
        2.2
      See Also:
        Constant Field Values

    - #### ALL

          static final String ALL

      For use with `addCategory(java.lang.String)` and `removeCategory(java.lang.String)` calls. This category includes all members in the persistent type.

      Using this category also sets the fetch-depth for the members in the default fetch group.

      Since:
        2.2
      See Also:
        Constant Field Values

  - ### Method Detail

    - #### hashCode

          int hashCode()

      Return the hashCode for this instance. The hash code should combine both the class and fetch group name. The hash codes for two equal instances must be identical.
      Overrides:
        `hashCode` in class `Object`
      Returns:
        the hash code
      Since:
        2.2

    - #### equals

          boolean equals(Object other)

      Return whether this instance is equal to the other. The equals method must compare the class for identity and the fetch group name for equality.
      Overrides:
        `equals` in class `Object`
      Returns:
        whether this instance is equal to the other
      Since:
        2.2

    - #### getName

          String getName()

      Get the name of this FetchGroup. The name is set only in the factory method.
      Returns:
        the name
      Since:
        2.2

    - #### getType

          Class getType()

      Get the persistent type (class or interface) of this FetchGroup. The persistent type is set only in the factory method(s).
      Returns:
        the persistent type
      Since:
        2.2

    - #### getPostLoad

          boolean getPostLoad()

      Get the post-load property of this FetchGroup.
      Returns:
        the post-load property
      Since:
        2.2

    - #### setPostLoad

          FetchGroup setPostLoad(boolean postLoad)

      Set the post-load property of this FetchGroup.
      Parameters:
        `postLoad` - Whether to post load this fetch group
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### addMember

          FetchGroup addMember(String memberName)

      Add the member (field or property) to the set of members in this FetchGroup.
      Parameters:
        `memberName` - the name of a member to add to the FetchGroup
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the parameter is not a member of the persistent type
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### addMembers

          FetchGroup addMembers(String... memberNames)

      Add the member (field or property) to the set of members in this FetchGroup. Duplicates are ignored.
      Parameters:
        `memberNames` - the names of members to add to the FetchGroup
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if any parameter is not a member of the persistent type
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### removeMember

          FetchGroup removeMember(String memberName)

      Remove the member (field or property) from the set of members in this FetchGroup.
      Parameters:
        `memberName` - Name of the member of the class to remove from the FetchGroup.
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the parameter is not a member of the persistent type
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### removeMembers

          FetchGroup removeMembers(String... memberNames)

      Remove the member (field or property) from the set of members in this FetchGroup. Duplicates in the parameter list are eliminated before removing them from the membership.
      Parameters:
        `memberNames` - Member names of the class to remove from this FetchGroup.
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if any parameter is not a member of the persistent type
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### addCategory

          FetchGroup addCategory(String categoryName)

      Add the members (fields or properties) of the named category to the set of members in this FetchGroup. This method first resolves the category name to a set of members and then adds the members as if `addMembers(java.lang.String...)` was called. After this method executes, the category is not remembered.
      Parameters:
        `categoryName` - Category to add to this FetchGroup.
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### removeCategory

          FetchGroup removeCategory(String categoryName)

      Remove the members (fields or properties) of the named category from the set of members in this FetchGroup. This method first resolves the category name to a set of members and then removes the members as if `removeMembers(java.lang.String...)` was called. After this method executes, the category is not remembered.
      Parameters:
        `categoryName` - Category to remove from this FetchGroup.
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### setRecursionDepth

          FetchGroup setRecursionDepth(String memberName,
                                       int recursionDepth)

      Set the recursion-depth for this member. The default is 1. A value of 0 means don't fetch the member (as if the member were omitted entirely). A value of -1 means fetch all instances reachable via this member.
      Parameters:
        `memberName` - the name of the field or property
        `recursionDepth` - the value for the recursion-depth property
      Returns:
        the FetchGroup
      Throws:
        `JDOUserException` - if the member does not exist
        `JDOUserException` - if the FetchGroup is unmodifiable
      Since:
        2.2

    - #### getRecursionDepth

          int getRecursionDepth(String memberName)

      Get the recursion-depth for this member.
      Parameters:
        `memberName` - the name of the field or property
      Returns:
        the recursion-depth for this member
      Throws:
        `JDOUserException` - if the member is not in the FetchGroup
      Since:
        2.2

    - #### getMembers

          Set getMembers()

      Return an immutable Set of String containing the names of all members. The Set is a copy of the currently defined members and will not change based on subsequent changes to the membership in the FetchGroup.
      Returns:
        an immutable Set containing the names of all members in the FetchGroup
      Since:
        2.2

    - #### setUnmodifiable

          FetchGroup setUnmodifiable()

      Make this FetchGroup unmodifiable. If already unmodifiable, this method has no effect.
      Returns:
        the FetchGroup
      Since:
        2.2

    - #### isUnmodifiable

          boolean isUnmodifiable()

      Return whether this FetchGroup is unmodifiable. If so, methods `setPostLoad(boolean)`, `addMember(java.lang.String)`, `removeMember(java.lang.String)`, `addMembers(java.lang.String...)`, `removeMembers(java.lang.String...)`, `addCategory(java.lang.String)`, and `removeCategory(java.lang.String)` will throw `JDOUserException`.
      Returns:
        whether the FetchGroup is unmodifiable
      Since:
        2.2

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