com.erudika.para.core

Interface Linkable

All Known Subinterfaces:

ParaObject

All Known Implementing Classes:

Address, App, Linker, Sysprop, Tag, Thing, Translation, User, Vote

public interface Linkable

Applied to all ParaObjects by default. Allows an object to be linked to another object. A link can be: 1-1, 1-* or *-*. One-to-one and one-to-many links are implemented using the parentid field. Many-to-many links are implemented using Linker objects.

Author:

Alex Bogdanovski [alex@erudika.com]

See Also:

Linker

Method Summary

Modifier and Type	Method and Description
Long	countChildren(String type) Count the total number of child objects for this object.
Long	countLinks(String type2) Count the total number of links between this object and another type of object.
void	deleteChildren(String type) Deletes all child objects permanently.
<P extends ParaObject> List<P>	findChildren(String type, String query, Pager... pager) Search through all child objects.
<P extends ParaObject> List<P>	findLinkedObjects(String type, String field, String query, Pager... pager) Similar to findChildren(java.lang.String, java.lang.String, com.erudika.para.utils.Pager...) but for many-to-many relationships.
<P extends ParaObject> List<P>	getChildren(String type, Pager... pager) Returns all child objects linked to this object.
<P extends ParaObject> List<P>	getChildren(String type, String field, String term, Pager... pager) Returns all child objects linked to this object.
<P extends ParaObject> List<P>	getLinkedObjects(String type, Pager... pager) Similar to getChildren(java.lang.String, com.erudika.para.utils.Pager...) but for many-to-many relationships.
List<Linker>	getLinks(String type2, Pager... pager) Returns all links between this type object and another type of object.
boolean	isLinked(ParaObject toObj) Checks if a given object is linked to this one.
boolean	isLinked(String type2, String id2) Checks if this object is linked to another.
String	link(String id2) Links an object to this one in a many-to-many relationship.
void	unlink(String type, String id2) Unlinks an object from this one.
void	unlinkAll() Unlinks all objects that are linked to this one.

Method Detail

countLinks

Long countLinks(String type2)

Count the total number of links between this object and another type of object.

Parameters:

type2 - the other type of object

Returns:

the number of links

getLinks

List<Linker> getLinks(String type2,
                      Pager... pager)

Returns all links between this type object and another type of object.

Parameters:

type2 - the other type of object

pager - a Pager

Returns:

a list of Linker objects in a many-to-many relationship with this object.

getLinkedObjects

<P extends ParaObject> List<P> getLinkedObjects(String type,
                                                Pager... pager)

Similar to getChildren(java.lang.String, com.erudika.para.utils.Pager...) but for many-to-many relationships.

Type Parameters:

P - type of linked objects

Parameters:

type - type of linked objects to look for

pager - a Pager

Returns:

a list of linked objects

findLinkedObjects

<P extends ParaObject> List<P> findLinkedObjects(String type,
                                                 String field,
                                                 String query,
                                                 Pager... pager)

Similar to findChildren(java.lang.String, java.lang.String, com.erudika.para.utils.Pager...) but for many-to-many relationships. Searches through all linked objects connected to this via a Linker object.

Type Parameters:

P - type of linked objects

Parameters:

type - type of linked objects to look for

pager - a Pager

field - the name of the field to target (within a nested field "nstd")

query - a query string

Returns:

a list of linked objects matching the search query

isLinked

boolean isLinked(String type2,
                 String id2)

Checks if this object is linked to another.

Parameters:

type2 - the other type

id2 - the other id

Returns:

true if the two are linked

isLinked

boolean isLinked(ParaObject toObj)

Checks if a given object is linked to this one.

Parameters:

toObj - the other object

Returns:

true if linked

link

String link(String id2)

Links an object to this one in a many-to-many relationship. Only a link is created. Objects are left untouched. The type of the second object is automatically determined on read.

Parameters:

id2 - the other id

Returns:

the id of the Linker object that is created

unlink

void unlink(String type,
            String id2)

Unlinks an object from this one. Only a link is deleted. Objects are left untouched.

Parameters:

type - the other type

id2 - the other id

unlinkAll

void unlinkAll()

Unlinks all objects that are linked to this one. Deletes all Linker objects. Only the links are deleted. Objects are left untouched.

countChildren

Long countChildren(String type)

Count the total number of child objects for this object.

Parameters:

type - the other type of object

Returns:

the number of links

getChildren

<P extends ParaObject> List<P> getChildren(String type,
                                           Pager... pager)

Returns all child objects linked to this object.

Type Parameters:

P - the type of children

Parameters:

type - the type of children to look for

pager - a Pager

Returns:

a list of ParaObject in a one-to-many relationship with this object

findChildren

<P extends ParaObject> List<P> findChildren(String type,
                                            String query,
                                            Pager... pager)

Search through all child objects. Only searches child objects directly connected to this parent via the parentid field.

Type Parameters:

P - the type of children

Parameters:

type - the type of children to look for

pager - a Pager

query - a query string

Returns:

a list of ParaObject in a one-to-many relationship with this object

getChildren

<P extends ParaObject> List<P> getChildren(String type,
                                           String field,
                                           String term,
                                           Pager... pager)

Returns all child objects linked to this object.

Type Parameters:

P - the type of children

Parameters:

type - the type of children to look for

field - the field name to use as filter

term - the field value to use as filter

pager - a Pager

Returns:

a list of ParaObject in a one-to-many relationship with this object

deleteChildren

void deleteChildren(String type)

Deletes all child objects permanently.

Parameters:

type - the children's type.