Content of an property dependent on another property value - jsonschema

Question

I have the following schema, which "works", but does not enforce all the rules required of it.
I get JSON with a series of questions that have a templateType and data properties. There are different templates for each type, and the type must fit the template (or the client doesn't know how to layout the data).
The schema validates the templateType as an enum, and that the data fits one of the templates, but there's no correlation between the type and data structure (e.g. I could get templateType yesNo and data structure for multiSelect).
I'd like it to validate that the templateType matches the data structure. I can't change the format of the generated JSON, only the schema that validates it. None of the questions I've looked at seem to provide a solution.
For help, the schema can be pasted into the editor at http://jeremydorn.com/json-editor/, which generates a form from the schema and JSON data based on selections and data entered into the form.
{
"definitions": {
"question": {
"type": "array",
"title": "Question",
"items": {
"$ref": "#/definitions/template"
}
},
"template": {
"type": "object",
"title": "Question template",
"required": ["templateType","data"],
"properties": {
"templateType": {
"type": "string",
"enum": ["yesNo","multiSelect"]
},
"data": {
"oneOf": [
{"$ref": "#/definitions/yesNo"},
{"$ref": "#/definitions/multiSelect"}
]
}
}
},
"yesNo": {
"type": "object",
"title": "Yes/No question",
"additionalProperties": false,
"properties": {
"label": {
"type": "string"
}
}
},
"multiSelect": {
"type": "array",
"title": "Multi-select question",
"items": {
"type": "string",
"title": "Label for option",
"additionalProperties": false
}
}
},
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"items": {
"$ref": "#/definitions/question"
}
}

Answer 1

Have you considered using if, then, else keywords in your schema? They're part of JSON Schema draft-07
It would look like this:
{
"definitions": {
"question": {
"type": "array",
"title": "Question",
"items": {
"$ref": "#/definitions/template"
}
},
"template": {
"type": "object",
"title": "Question template",
"required": ["templateType","data"],
"properties": {
"templateType": {
"type": "string",
"enum": ["yesNo","multiSelect"]
},
"data": {
"if": { "properties": { "templateType": { "pattern": "^yesNo$" } } },
"then": { "$ref": "#/definitions/yesNo" },
"else": { "$ref": "#/definitions/multiSelect" }
}
}
},
"yesNo": {
"type": "object",
"title": "Yes/No question",
"additionalProperties": false,
"properties": {
"label": {
"type": "string"
}
}
},
"multiSelect": {
"type": "array",
"title": "Multi-select question",
"items": {
"type": "string",
"title": "Label for option",
"additionalProperties": false
}
}
},
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"items": {
"$ref": "#/definitions/question"
}
}
If if/then/else isn't supported by your validator, an alternative could be:
{
"definitions": {
"question": {
"type": "array",
"title": "Question",
"items": {
"$ref": "#/definitions/template"
}
},
"template": {
"type": "object",
"title": "Question template",
"required": ["templateType","data"],
"anyOf": [
{
"properties": {
"templateType": { "type": "string", "pattern": "yesNo" },
"data": { "$ref": "#/definitions/yesNo" }
}
},
{
"properties": {
"templateType": { "type": "string", "pattern": "multiSelect" },
"data": { "$ref": "#/definitions/multiSelect" }
}
}
]
},
"yesNo": {
"type": "object",
"title": "Yes/No question",
"additionalProperties": false,
"properties": {
"label": {
"type": "string"
}
}
},
"multiSelect": {
"type": "array",
"title": "Multi-select question",
"items": {
"type": "string",
"title": "Label for option",
"additionalProperties": false
}
}
},
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "array",
"items": {
"$ref": "#/definitions/question"
}
}