
Flow mappings in YAML represent the unordered collection of key value pairs. They are also called as mapping node. Note that keys should be maintained unique. If there is a duplication of keys in flow mapping structure, it will generate an error. The key order is generated in serialization tree.
An example of flow mapping structure is shown below −
%YAML 1.1
paper:
uuid: 8a8cbf60-e067-11e3-8b68-0800200c9a66
name: On formally undecidable propositions of Principia Mathematica and related systems I.
author: Kurt Gödel.
tags:
- tag:
uuid: 98fb0d90-e067-11e3-8b68-0800200c9a66
name: Mathematics
- tag:
uuid: 3f25f680-e068-11e3-8b68-0800200c9a66
name: Logic
The output of mapped sequence (unordered list) in JSON format is as shown below −
{
"paper": {
"uuid": "8a8cbf60-e067-11e3-8b68-0800200c9a66",
"name": "On formally undecidable propositions of Principia Mathematica and related systems I.",
"author": "Kurt Gödel."
},
"tags": [
{
"tag": {
"uuid": "98fb0d90-e067-11e3-8b68-0800200c9a66",
"name": "Mathematics"
}
},
{
"tag": {
"uuid": "3f25f680-e068-11e3-8b68-0800200c9a66",
"name": "Logic"
}
}
]
}
If you observe this output as shown above, it is observed that the key names are maintained unique in YAML mapping structure.