Changes

If you want one or multiple objects to refer to a single target object each, a reference [[Reference]] is what you need. You can either ask an object about the one it refers to, or ask a target object about all objects referring to it via a reference. This is useful, if you want to connect objects but there is no necessity for '''both''' "sides" to be connected to multiple other objects.

In order for an object referring to achieve thisanother object, the following requirements must be met:

** A [[Reference|Reference]] object defining the target MetaClass should be set on the MetaProperty.

* # Create a new [[Reference]] ([[HowTo:Create_a_new_Reference]]).* # Set the [[MetaClass]] of '''B''' on the '''TARGETTYPE''' property of the previously created reference, as explained in the HowTo above. * # Make sure there is a [[MetaProperty]] on the MetaClass of object '''A''' you can use. If necessary, create a new MetaProperty instance and relate it to the MetaClass of '''A''' via the MetaClass to MetaProperty relation ([[HowTo:Add_a_MetaProperty_to_a_MetaClass]]).* # Set the previously created reference on the new MetaProperty ([[HowTo:Create_a_new_MetaProperty#REFERENCE]]).* # Make sure all changes are saved.* # Open the Bulk Editor for the MetaClass of '''A''' and set the property value for the new MetaProperty on '''A''' to '''B''', in one of the following ways:** ## dragging and dropping object '''B''' onto the cell** ## selecting the object '''B''' from the dialog appearing after double-clicking the cell * # Save object '''A'''. The connection is now established and can be used, e.g., in the ACM view or by programmatic customizing. == Connect objects via Relation == If you want to connect one source object to multiple other target objects, but it should also be possible for a target object to be connected to multiple source objects, you require a [[Relation]].  Essentially, every individual relation connection is a {{{UBIK}}} object referring both to the source object and the target object (we say, '''left''' and '''right''' target). This allows us to have many such connections for the same left ''and'' right object, whereas a reference property would just enable many connections for the target object (right). For simplicity, let's call the left object '''A''' and the right object '''B'''. '''A''' is related to '''B'''. In order for two objects to be related, the following requirements must be met:* There must be a Relation defining the connection between the MetaClasses of '''A''' and '''B'''.** The Relation requires a RelationData MetaClass describing the individual relation connections, e.g., between '''A''' and '''B'''.** On the Relation and the RelationData MetaClass, the respective left and right target MetaClasses must be configured.* There must be a RelationData instance, referring to '''A''' via the '''Left target''' and referring to '''B''' via the '''Right target''' reference property.  You can achieve this with the following steps:# Create a new Relation ([[HowTo:Create_a_new_Relation]]).# Set the MetaClass of '''A''' on the '''TARGETTYPELEFT''' property and set the MetaClass of '''B''' on the '''TARGETTYPERIGHT''' property of the relation, as explained in the HowTo linked above.# Set a RelationData template MetaClass on the '''RELATIONDATA''' property of the relation, as described in the HowTo linked above.# Relate '''A''' to '''B''' in one of the following ways:## Open the actual RelationData MetaClass (not the template, see the HowTo linked above) in the Bulk Editor and create a new instance, setting the '''Left target''' property value to '''A''' and the '''Right target''' property value to '''B'''.## Open '''A''' in the Relation Editor. In the tree view you see now, drag '''B''' onto the tree node for the previously created relation.# Save all changes. The connection is now established and can be used, e.g., in the ACM view or by programmatic customizing.