Object Diagram

Definition of objects

You define instances of objects using the object keyword.

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@startuml
object firstObject
object "My Second Object" as o2
@enduml

Relations between objects

Relations between objects are defined using the following symbols :

Type Symbol Image
Extension <|--
Composition *--
Aggregation o--

It is possible to replace -- by .. to have a dotted line.

Knowing those rules, it is possible to draw the following drawings.

It is possible a add a label on the relation, using : followed by the text of the label.

For cardinality, you can use double-quotes "" on each side of the relation.

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@startuml
object Object01
object Object02
object Object03
object Object04
object Object05
object Object06
object Object07
object Object08

Object01 <|-- Object02
Object03 *-- Object04
Object05 o-- "4" Object06
Object07 .. Object08 : some labels
@enduml

Associations objects

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@startuml
object o1
object o2
diamond dia
object o3

o1  --> dia
o2  --> dia
dia --> o3
@enduml

Adding fields

To declare fields, you can use the symbol : followed by the field's name.

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@startuml

object user

user : name = "Dummy"
user : id = 123

@enduml

It is also possible to group all fields between brackets {}.

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@startuml

object user {
  name = "Dummy"
  id = 123
}

@enduml

Common features with class diagrams

Map table or associative array

You can define a map table or associative array, with map keyword and => separator.

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@startuml
map CapitalCity {
 UK => London
 USA => Washington
 Germany => Berlin
}
@enduml

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@startuml
map "Map **Contry => CapitalCity**" as CC {
 UK => London
 USA => Washington
 Germany => Berlin
}
@enduml

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@startuml
map "map: Map<Integer, String>" as users {
 1 => Alice
 2 => Bob
 3 => Charlie
}
@enduml

And add link with object.

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@startuml
object London

map CapitalCity {
 UK *-> London
 USA => Washington
 Germany => Berlin
}
@enduml

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@startuml
object London
object Washington
object Berlin
object NewYork

map CapitalCity {
 UK *-> London
 USA *--> Washington
 Germany *---> Berlin
}

NewYork --> CapitalCity::USA
@enduml

[Ref. #307]

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@startuml
package foo {
    object baz
}

package bar {
    map A {
        b *-> foo.baz
        c =>
    }
}

A::c --> foo
@enduml

[Ref. QA-12934]

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@startuml
object Foo
map Bar {
  abc=>
  def=>
}
object Baz

Bar::abc --> Baz : Label one
Foo --> Bar::def : Label two
@enduml

[Ref. #307]

Program (or project) evaluation and review technique (PERT) with map

You can use map table in order to make Program (or project) evaluation and review technique (PERT) diagram.

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@startuml PERT
left to right direction
' Horizontal lines: -->, <--, <-->
' Vertical lines: ->, <-, <->
title PERT: Project Name

map Kick.Off {
}
map task.1 {
    Start => End
}
map task.2 {
    Start => End
}
map task.3 {
    Start => End
}
map task.4 {
    Start => End
}
map task.5 {
    Start => End
}
Kick.Off --> task.1 : Label 1
Kick.Off --> task.2 : Label 2
Kick.Off --> task.3 : Label 3
task.1 --> task.4
task.2 --> task.4
task.3 --> task.4
task.4 --> task.5 : Label 4
@enduml

[Ref. QA-12337]