Some JSON preprocessing capabilities are included in PlantUML, and available for all diagrams. That extends the current preprocessing. 🛈 If you are looking for how to display JSON data: see rather Display JSON Data. In addition to existing type (String and Integer), you can define JSON variable. Example:
!$foo = { "name": "John", "age" : 30 }
Corresponding of this structure: 🎉 Copied!  | @startjson
{
"$foo": { "name": "John", "age" : 30 }
}
@endjson
|
Once a variable is defined, you can access to its members: 🎉 Copied!  | @startuml
!$foo = { "name": "John", "age" : 30 }
Alice -> Bob : Do you know **$foo.name** ?
@enduml
|
It is possible to use complex JSON objects and arrays, with definition on several lines. Let $foo , the structure: 🎉 Copied!  | @startjson
{
"$foo":{ "company": "Skynet", "employees" : [
{"name" : "alice", "salary": 100 },
{"name" : "bob", "salary": 50} ]
}
}
@endjson
| You can acess to the values: $foo.employees[0].name $foo.employees[0].salary
🎉 Copied!  | @startuml
!$foo = { "company": "Skynet", "employees" : [
{"name" : "alice", "salary": 100 },
{"name" : "bob", "salary": 50} ]
}
start
:The salary of <u>$foo.employees[0].name</u> is <u>$foo.employees[0].salary</u>;
@enduml
| Or using intermediate variables: !$attribute_1="name" !$attribute_2="salary" to acess to the values: $foo.employees[0][$attribute_1] $foo.employees[0][$attribute_2]
🎉 Copied!  | @startuml
!$foo = { "company": "Skynet", "employees" : [
{"name" : "alice", "salary": 100 },
{"name" : "bob", "salary": 50} ]
}
!$attribute_1="name"
!$attribute_2="salary"
start
:The salary of <u>$foo.employees[0][$attribute_1]</u> is <u>$foo.employees[0][$attribute_2]</u>;
@enduml
|
Some standard function provides a way to load JSON object from URL or local files:
!$foo = %loadJSON("http://foo.net/users/list.json")
!$foo2 = %loadJSON("myDir/localFile.json")
Available since 1.2021.15 If you define array, you can loop over. 🎉 Copied!  | @startmindmap
!$foo = { "company": "Skynet", "employees" : [
{"name" : "alice", "salary": 100 },
{"name" : "bob", "salary": 50} ]
}
* The salary of
!foreach $emp in $foo.employees
** **$emp.name**
*** is
**** **$emp.salary**
!endfor
@endmindmap
| [SW] Some remarks - for or better foreach ? ->
foreach - It would be nice to also have "break" and "continue"
- It would be nice to also have the for or while loop with a standard variable
From a example worked in a forum question, with this JSON structure: 🎉 Copied!  | @startjson
{
"data":
{
"participants": [
{"name": "XYZ", "as": "xyz"},
{"name": "RST", "as": "rst"},
{"name": "UVW", "as": "uvw"}]
}
}
@endjson
|
🎉 Copied!  | @startuml
!unquoted function DRAW($x) return %set_variable_value($x, 1)
!procedure addComponent($part, $component, $as)
!if %variable_exists($part)
participant "$component" as $as
!endif
!end procedure
!procedure addBox2($part, $box, $colour, $data)
!if %variable_exists($part)
box "$box" #$colour
!foreach $item in $data.participants
addComponent($part, $item.name, $item.as)
!endfor
end box
!endif
!end procedure
DRAW(PART25)
!ifdef PART25
title TESTING (Boxes & Participants) //Part25//
!endif
!$data={
"participants": [
{"name": "XYZ", "as": "xyz"},
{"name": "RST", "as": "rst"},
{"name": "UVW", "as": "uvw"}]
}
addBox2("PART25", "New Box", "white", $data)
@enduml
|
Here is a self-descriptive example: 🎉 Copied!  | @startuml
left to right direction
!$data={"parts":[
{"shape": "cloud", "name": "id1", "colour": "#palegreen", "desc": "some text"},
{"shape": "folder", "name": "id2", "colour": "#lightblue", "desc": "more text"},
{"shape": "database", "name": "id3", "colour": "#pink", "desc": "even more text"}
]}
rectangle Outer {
rectangle Inner #tan as "
{{json
$data
}}
"
together {
!foreach $part in $data.parts
$part.shape $part.colour $part.name as "$part.desc"
Inner --> $part.name
!endfor
}
}
@enduml
| [Adapted from QA-12917] | |