Singleton

The Data model type resource called data/Datamodel has an attribute singleton that can take any of 3 values:

• None (default): no singleton constraint
• system: a system singleton that only allows one instance throughout the system
• hierarchy: a hierarchy singleton that only allows one instance every hierarchy

For example, the snippet below shows a simple data/Datamodel instance called LoginBanner that can itself only have one instance per hierarchy:

"data": {
    "doc": "doc",
    "Meta": {
        "operations": [
            "add",
            "clone",
            "export",
            "export_bulkload_template",
            "get",
            "help",
            "move",
            "list",
            "migration",
            "transform",
            "remove",
            "tag",
            "tag_version",
            "update",
            "field_display_policy"
        ],
        "summary_attrs": [
            "login_banner"
        ],
        "singleton": "hierarchy",
        "attr_props": [
            {
                "title": "Login Banner",
                "required": true,
                "type": "string",
                "displayable": true,
                "name": "login_banner"
            }
        ]
    },
    "name": "LoginBanner"
}