Home What's New ? Getting Started Online Server Running F.A.Q. Download Forum Theme Preprocessing Standard Library PDF Guide Hitchhiker's Guide
PlantUML Language specification Preprocessing Json

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Preprocessing JSON

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.

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Variable definition

In addition to existing type (String and Integer), you can define JSON variable.

JSON Object

Example: 

!$foo = { "name": "John", "age" : 30 }

Corresponding of this structure:

🎉 Copied! 

@startjson
{
"$foo": { "name": "John", "age" : 30 }
}
@endjson

JSON Array

Example: 

!$foo = ["abc", "def", "ghi"]

Corresponding of this structure:

🎉 Copied! 

@startjson
["abc", "def", "ghi"]
@endjson

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Access to data

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

🎉 Copied! 

@startuml
!$foo = ["abc", "def", "ghi"]
Alice <- Bob : Yes he loves **$foo[2]** letters?
@enduml

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Complex structures

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

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Loading data

Some standard function provides a way to load JSON object from URL or local files: 

!$foo = %load_json("http://foo.net/users/list.json")
!$foo2 = %load_json("myDir/localFile.json")

Available since 1.2021.15

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Loop [foreach]

If you define array, you can loop over.

🎉 Copied! 

@startmindmap
* root
!foreach $item in ["abc", "def", "ghi"]
  ** **$item**
!endfor
@endmindmap

🎉 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

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Full Example

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

Edit in DokuwikiEdit in AsciidocEdit in Markdown
Self-descriptive example

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]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%get_json_keys builtin function

You can use %get_json_keys to get all the keys of one level on a JSON structure.

🎉 Copied! 

@startuml
!$myjson = {
"root" : [{
    "fruits": [
        {"name": "apple", "colorId": "1"},
        {"name": "pear", "colorId": "2"},
        {"name": "pineapple", "colorId": "3"}
    ]
},
{
    "colors": [
        {"id": "1", "name": "red"},
        {"id": "2", "name": "green"},
        {"id": "3", "name": "yellow"}
    ]
}]
}

!foreach $key in %get_json_keys($myjson.root)
     rectangle $key
!endfor
@enduml

🎉 Copied! 

@startwbs
!$json_object = {
  "name": "Mark McGwire", "hr": 65, "avg":  0.278
}

* json_object
 * keys of json_object
!foreach $key in %get_json_keys($json_object)
  * $key
!endfor
@endwbs

[Ref. QA-15360, QA-15423]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%get_json_type builtin function

You can use %get_json_type to get the type of an element of a JSON structure (returns a string).

🎉 Copied! 

@startuml
!$json_object = {
  "name": "Mark McGwire", "hr": 65, "avg":  0.278,
  "letters": ["a", "b", "c"]
}

label l [
=json_object:
{{json
$json_object
}}

|= $variable          |= <U+0025>get_json_type($var)         |
| json_object         | %get_json_type($json_object)         |
| json_object.name    | %get_json_type($json_object.name)    |
| json_object.hr      | %get_json_type($json_object.hr)      |
| json_object.letters | %get_json_type($json_object.letters) |

Test on type:
!if %get_json_type($json_object.letters)=="array"
  json_object.letters is an **%get_json_type($json_object.letters)**
!endif
]
@enduml

[Ref. QA-15360]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%json_key_exists builtin function

You can use %json_key_exists to know if a key exists on a JSON structure (returns a boolean).

🎉 Copied! 

@startuml
!$json_object= {
  "name": "Mark McGwire", "hr": 65, "avg":  0.278
}

label l [
|= key  |= <U+0025>json_key_exists(json_object, key)   |
| "hr"  | %json_key_exists($json_object, "hr") |
| "foo" | %json_key_exists($json_object, "foo")|
| null  | %json_key_exists($json_object, null) |
]
@enduml

[Ref. QA-15423]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%size builtin function

You can use %size to know the size of different elements on a JSON structure.

For each type here are the return value:
Type Return value
JSON Object the number of pairs it contains
JSON Array the number of values it contains
string value the number of characters it contains
numeric value zero
true/false/null zero

🎉 Copied! 

@startuml
!$json_object= {
  "name"   : "Mark McGwire",
  "hr"     : 65,
  "avg"    : 0.278,
  "letters": ["a", "b", "c"]
}

label l [
|= $variable          |= <U+0025>get_json_type($var)         |= <U+0025>size($var)         |
| json_object         | %get_json_type($json_object)         | %size($json_object)         |
| json_object.name    | %get_json_type($json_object.name)    | %size($json_object.name)    |
| json_object.hr      | %get_json_type($json_object.hr)      | %size($json_object.hr)      |
| json_object.letters | %get_json_type($json_object.letters) | %size($json_object.letters) |
]
@enduml

[Ref. QA-14901]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%json_add builtin function

You can use %json_add to add element on an existing JSON structure (returns the final JSON structure).

🎉 Copied! 

@startjson
!$a = {"age" : 30}
%json_add($a, name, Bob)
@endjson

🎉 Copied! 

@startjson
!$a = {"age" : 30, "name":"Bob"}
%json_add($a, name, Sally)
@endjson

🎉 Copied! 

@startjson
!$a = {"age" : 30, "name":"Bob"}
!$b = [1, 2, {"a":0, "b":1}]
%json_add($a, tab, $b)
@endjson

[Ref. PR-1742 and PR-1757]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%json_remove builtin function

You can use %json_remove to remove element on an existing JSON structure (returns the final JSON structure).

🎉 Copied! 

@startjson
!$a = [1, 2, 3]
%json_remove($a, 1)
@endjson

🎉 Copied! 

@startjson
!$a = {"age" : 30, "name":"Bob"}
%json_remove($a, age)
@endjson

[Ref. PR-1742]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%json_set builtin function

You can use %json_set to set element on an existing JSON structure (returns the final JSON structure).

🎉 Copied! 

@startjson
!$a = {"age" : 30, "name":"Bob"}
%json_set($a, name, Sally)
@endjson

[Ref. PR-1761]

🎉 Copied! 

@startjson
!$a = {"partlen": "2", "color": {"A":"red", "B":"blue"}}
!$b = {"color":{"A":"black"}}
%json_set($a, $b)
@endjson

[Ref. PR-1782]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%json_merge builtin function

You can use %json_merge to merge JSON structures (returns the final JSON structure).

🎉 Copied! 

@startjson
!$a = {"age" : 30, "name":"Bob"}
!$b = {"glasses": true}
%json_merge($a, $b)
@endjson

[Ref. PR-1763]

Edit in DokuwikiEdit in AsciidocEdit in Markdown
%str2json builtin function

You can use %str2json to transform a string value to a JSON structure.

Here are some example:

🎉 Copied! 

@startuml
label l [
<#ccc>|= String_value |= <U+0025>get_json_type(<U+0025>str2json(String_value)) |
| [1, 2, 3]           | %get_json_type(%str2json('[1, 2, 3]'))                 |
| {"a":1, "b":2}      | %get_json_type(%str2json('{"a":1, "b":2}'))            |
| true                | %get_json_type(%str2json('true'))                      |
| null                | %get_json_type(%str2json('null'))                      |
| it's a string       | %get_json_type(%str2json("it's a string"))             |
| 42                  | %get_json_type(%str2json('42'))                        |
]
@enduml

🎉 Copied! 

@startuml
label l [
<#ccc>|= String_value |= <U+0025>get_json_type(<U+0025>str2json(String_value)) |
!foreach $item in ["[1, 2, 3]", "{\"a\":1, \"b\":2}", "true", "null", "it's a string", "42"]
| $item | %get_json_type(%str2json($item)) |
!endfor
]
@enduml

🚩 Known issue: Unfortunately, be careful with quote management.

Some issues occur when a single quote is contained in a string when the entire string is surrounded by single quote.

[Ref. PR-1742]

Privacy Policy      Advertise