JSON前処理

PlantUMLには、いくつかのJSON前処理機能が搭載されており、すべてのダイアグラムで利用できます。

これは、既存の前処理機能を拡張します。

🛈 JSONデータを表示する方法を探している場合は、「JSONデータを表示する」を確認してください。

変数定義

既存の型(StringInteger)に加えて、JSON型の変数を定義できます。

例:

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

これは、次のような構造に対応します:

🎉 Copied!

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

WARNING
 This translation need to be updated. 
WARNING

データへのアクセス

変数を定義すると、そのメンバにアクセスすることができます:

🎉 Copied!

@startuml
!$foo = { "name": "John", "age" : 30 }
Alice -> Bob : Do you know **$foo.name** ?
@enduml

WARNING
 This translation need to be updated. 
WARNING

複雑な構造

複数行にわたる、複雑なJSONオブジェクトや配列を定義することもできます。

$fooを定義します:

🎉 Copied!

@startjson
{
"$foo":{ "company": "Skynet", "employees" : [
  {"name" : "alice", "salary": 100 },
  {"name" : "bob", "salary": 50} ]
}
}
@endjson

次のように、値にアクセスできます:
  • $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

もしくは、中間変数を使用して、
  • !$attribute_1="name"
  • !$attribute_2="salary"
値にアクセスできます:
  • $foo.employees[0][$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

データのロード

標準関数を使用して、URLまたはローカルファイルからJSONオブジェクトをロードできます:

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

1.2021.15 以降で利用可能

繰り返し [foreach]

配列を定義すると、それに対してループ処理を行うことができます。

🎉 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

[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
WARNING
 This translation need to be updated. 
WARNING

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

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]

%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]

%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]

%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]

%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]

%json_add builtin function

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

[Ref. PR-1742 and PR-1757]


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