Question 372773 in Json Question posted in
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JSON schema validation with if-clause to choose different properties for same object

I like to write a JSON schema validation for this kind of yml

stages:

  - template: template-a.yml
    parameters:
      a-param1: abc
      a-param2: xy

  - template: template-b.yml
    parameters:
      b-param1: df
      b-param2: yz

So depending of the value of property "template", the property object "parameters" should have different properties.

I tried something like this, but if/then is not working for the object properties.
(if the property is on same level like "template" it’s working)

{
    "$schema": "http://json-schema.org/draft-07/schema#",
    "$ref": "#/definitions/azure-templates",
    "definitions": {
        "azure-templates": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
                "stages": {
                    "type": "array",
                    "items": {
                        "anyOf": [
                            {
                                "$ref": "#/definitions/template-select"
                            }
                        ]
                    }
                }
            },
            "required": [
                "stages"
            ],
            "title": "azure-pipeline"
        },
        "template-params-a": {
            "if": {
                "properties": {
                    "template": {
                        "const": "template-a.yml"
                    }
                },
                "required": [
                    "template"
                ]
            },
            "then": {
                "properties": {
                    "parameters": {
                        "type": "object",
                        "additionalProperties": false,
                        "properties": {
                            "a-param1": {
                                "type": "string"
                            },
                            "a-param2": {
                                "type": "string"
                            }
                        }
                    }
                }
            }
        },
        "template-params-b": {
            "if": {
                "properties": {
                    "template": {
                        "const": "template-b.yml"
                    }
                },
                "required": [
                    "template"
                ]
            },
            "then": {
                "properties": {
                    "parameters": {
                        "type": "object",
                        "additionalProperties": false,
                        "properties": {
                            "b-param1": {
                                "type": "string"
                            },
                            "b-param2": {
                                "type": "string"
                            }
                        }
                    }
                }
            }
        },
        "template-select": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
                "template": {
                    "enum": [
                        "template-a.yml",
                        "template-b.yml"
                    ]
                }
            },
            "allOf": [
                {
                    "$ref": "#/definitions/template-params-a",
                    "$ref": "#/definitions/template-params-b"
                }
            ],
            "required": [
                "template"
            ],
            "title": "Template"
        }
    }
}
Tags:

2

Answers


  1. 0
    • the root $ref should be wrapped in an allOf. This behavior was later updated in Draft 2019-09 which allowed a root $ref and definitions(or any other keyword as a sibling) to be validated
    • the additionalProperties:false in your template-select schema is preventing the parameters from being used because in draft-07, allOf and additionalProperties:false don’t play nicely together without some gymnastics in the schema. (if you really want to enforce this constraint, I’ve updated the schema)
    • I removed the anyOf in the items schema, it’s not necessary with a single schema ref.
    {
    "$schema": "http://json-schema.org/draft-07/schema#",
    "allOf": [
        {
            "$ref": "#/definitions/azure-templates"
        }
    ],
    "definitions": {
        "azure-templates": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
                "stages": {
                    "type": "array",
                    "items": {
                        "$ref": "#/definitions/template-select"
                    }
                }
            },
            "required": [
                "stages"
            ],
            "title": "azure-pipeline"
        },
        "template-params-a": {
            "if": {
                "properties": {
                    "template": {
                        "const": "template-a.yml"
                    }
                },
                "required": [
                    "template"
                ]
            },
            "then": {
                "properties": {
                    "parameters": {
                        "type": "object",
                        "additionalProperties": false,
                        "properties": {
                            "a-param1": {
                                "type": "string"
                            },
                            "a-param2": {
                                "type": "string"
                            }
                        }
                    }
                }
            }
        },
        "template-params-b": {
            "if": {
                "properties": {
                    "template": {
                        "const": "template-b.yml"
                    }
                },
                "required": [
                    "template"
                ]
            },
            "then": {
                "properties": {
                    "parameters": {
                        "type": "object",
                        "additionalProperties": false,
                        "properties": {
                            "b-param1": {
                                "type": "string"
                            },
                            "b-param2": {
                                "type": "string"
                            }
                        }
                    }
                }
            }
        },
        "template-select": {
            "type": "object",
            "additionalProperties": false,
            "properties": {
                "template": {
                    "enum": [
                        "template-a.yml",
                        "template-b.yml"
                    ]
                }, 
                "parameters": true
            },
            "allOf": [
                {"$ref": "#/definitions/template-params-a"},
                {"$ref": "#/definitions/template-params-b"}
            ],
            "required": [
                "template", "parameters"
            ],
            "title": "Template"
        }
    }
}
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  2. 0

    Using VSC, it seems to suggest the properties correctly, based on the conditional validation defined.

    VSC sample

    VSC sample

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