Is it possible with JSON Schema to specify a string length that depends on the value of a property in the item that is being validated?
For example, I have a document with a "foo" property with value 3. I would like to ensure that the "bar" property is a string of at least size 3
Sample JSON
{
"foo": 3,
"bar": "111"
}
JSON Schema
{
"properties" : {
"foo": {
"type": "integer",
"minimum": 1
}
"bar": {
"type": "string",
"minLength": "{$foo}"
}
}
}
There is a v5 proposal for a $data keyword that would "allow schemas to use values from the data, specified using JSON Pointers or Relative JSON Pointers".
Using your example:
{
"properties" : {
"foo": {
"type": "integer",
"minimum": 1
}
"bar": {
"type": "string",
"minLength": { "$data": "1/foo" }
}
}
}
Support for the $data keyword will obviously depend upon the validator you are using. Some validators do support the v5 proposals.
Related
Can I put check on two fields in JSON schema ? Both field are of type array of objects. Conditions:
Either one of them can contain value at a time (i.e. other should be empty).
Both can be empty.
Any leads ?
// The schema
var schema = {
"id": "https://kitoutapi.lrsdedicated.com/v1/json_schemas/login-request#",
"$schema": "http://json-schema.org/draft-04/schema#",
"description": "Login request schema",
"type": "object",
"oneOf": [
{ "categories": {
"maxItems": 0
},
"positionedOffers": {
"minItems": 1
}},
{ "categories": {
"minItems": 1
},
"positionedOffers": {
"maxItems": 0
}}
],
"properties": {
"categories": {
"type": "array"
},
"positionedOffers": {
"type": "array"
}
},
"additionalProperties": false
};
// Test data 1
// This test should return a good result
var data1 = {
"positionedOffers":['hello'],
"categories":[],
}
For your requirement, I think I'd come at this from the other direction. Rather than saying
If one contains a value, the other must be empty, but both may be empty.
I'd say
At least one must be empty.
That leads you to use an anyOf with subschemas checking that each property is an empty array.
{
"id": "https://kitoutapi.lrsdedicated.com/v1/json_schemas/login-request#",
"$schema": "http://json-schema.org/draft-04/schema#",
"description": "Login request schema",
"type": "object",
"anyOf": [
{
"properties": {
"categories": {
"maxItems": 0
}
}
},
{
"properties": {
"positionedOffers": {
"maxItems": 0
}
}
}
],
"properties": {
"categories": {
"type": "array"
},
"positionedOffers": {
"type": "array"
}
},
"additionalProperties": false
}
Bonus Material
In your original post, you omitted the properties keywords under the oneOf. This may have been the cause of the schema's failure to validate. I've added it in the above.
Secondly, draft 4 is quite old at this point. You may be limited by the implementation you're using, but if you can, you should consider using a more recent version of JSON Schema. You can view available implementations and what versions they support on the JSON Schema implementations page.
I need to define a JSON schema for a JSON in which a field/key is called as the value of a previous field. Examples:
{
"key1": "SOME_VALUE",
"SOME_VALUE": "..."
}
{
"key1": "ANOTHER_VALUE",
"ANOTHER_VALUE": "..."
}
Moreover, the second field should be among the required ones.
I have been looking around but I am not sure JSON schema offers such feature. Maybe some advanced semantics check?
Thanks for the help
The only way you could do this is if you knew the values in advance, but it looks like this is not possible for you. This would need to be in your business logic validation as opposed to your format validation.
So, thanks to Relequestual suggestions, I managed to get to a solution.
Constraint: possible values of "key1" need to be finite and known in advance
Suppose we need a JSON schema for validating a JSON that:
Requires the string properties "required_simple_property1" and "required_simple_property2".
Requires the property "key1" as an enum with 3 possible values ["value1", "value2", "value3"].
Requires a third property, whose key must be the value taken by key1.
This can be accomplished with a schema like:
"oneOf": [
{
"required": [
"required_simple_property1",
"required_simple_property2",
"value1"
],
"properties": {
"key1": {
"type": "string",
"const": "value1"
}
}
},
{
"required": [
"required_simple_property1",
"required_simple_property2",
"value2"
],
"properties": {
"key1": {
"type": "string",
"const": "value2"
}
}
},
{
"required": [
"required_simple_property1",
"required_simple_property2",
"value3"
],
"properties": {
"key1": {
"type": "string",
"const": "value3"
}
}
}
],
"properties": {
"required_simple_property1": {
"type": "string"
},
"required_simple_property2": {
"type": "string"
},
"value1": {
... (anything)
},
"value2": {
... (anything)
},
"value3": {
... (anything)
},
}
Is it correct to make a definition (suppose with name "abc") and then refer to it from an attribute called "abc" whose type is "array"? Or it's incorrect and array and its items have to have different names?
Thanks!
{
"$schema": "http://json-schema.org/draft-07/schema#",
"description": "newSchema.json",
"title": "newSchema",
"type": "object",
"definitions": {
"abc": {
"properties": {
"some_col": {
"description": "hi",
"type": "integer"
}
}
}
},
"properties": {
"abc": {
"type": "array",
"items": {
"$ref": "#/definitions/abc"
}
}
}
}
It's a totally valid JSON structure and JSON Schema setup.
If you intend for others to read your generated schemas, you could add annotations to them to give additional information, such as "This is an array of [table]" and "this object represents a row in [table]".
See the Schema Annotations section of the JSON Schema draft-7 validation specification.
I have a simple JSON schema:
{
"properties": {
"name": {
"type": "string"
}
},
"type": "object"
}
It requires that name property is a string. This schema does not restrict additional properties, e.g.
{
name: 'foo',
url: 'http://foo'/
}
The latter is a valid input.
Is there a way to set a property value format requirement based on a conditional property name match?, e.g. any property that contains url string in it must correspond to the following schema:
{
"type": "string",
"format": "url"
}
Therefore, an input:
{
name: 'foo',
location_url: 'not-a-valid-url'
}
would cause an error because location_url does not contain a valid URL?
I'd imagine, a schema for something like this would look like:
{
"properties": {
"name": {
"type": "string"
}
},
"matchProperties": {
"/url/i": {
"type": "string",
"format": "url"
}
}
"type": "object"
}
where matchProperties is a keyword I made up.
For example a schema for a file system, directory contains a list of files. The schema consists of the specification of file, next a sub type "image" and another one "text".
At the bottom there is the main directory schema. Directory has a property content which is an array of items that should be sub types of file.
Basically what I am looking for is a way to tell the validator to look up the value of a "$ref" from a property in the json object being validated.
Example json:
{
"name":"A directory",
"content":[
{
"fileType":"http://x.y.z/fs-schema.json#definitions/image",
"name":"an-image.png",
"width":1024,
"height":800
}
{
"fileType":"http://x.y.z/fs-schema.json#definitions/text",
"name":"readme.txt",
"lineCount":101
}
{
"fileType":"http://x.y.z/extended-fs-schema-video.json",
"name":"demo.mp4",
"hd":true
}
]
}
The "pseudo" Schema note that "image" and "text" definitions are included in the same schema but they might be defined elsewhere
{
"id": "http://x.y.z/fs-schema.json",
"definitions": {
"file": {
"type": "object",
"properties": {
"name": { "type": "string" },
"fileType": {
"type": "string",
"format": "uri"
}
}
},
"image": {
"allOf": [
{ "$ref": "#definitions/file" },
{
"properties": {
"width": { "type": "integer" },
"height": { "type": "integer"}
}
}
]
},
"text": {
"allOf": [
{ "$ref": "#definitions/file" },
{ "properties": { "lineCount": { "type": "integer"}}}
]
}
},
"type": "object",
"properties": {
"name": { "type": "string"},
"content": {
"type": "array",
"items": {
"allOf": [
{ "$ref": "#definitions/file" },
{ *"$refFromProperty"*: "fileType" } // the magic thing
]
}
}
}
}
The validation parts of JSON Schema alone cannot do this - it represents a fixed structure. What you want requires resolving/referencing schemas at validation-time.
However, you can express this using JSON Hyper-Schema, and a rel="describedby" link:
{
"title": "Directory entry",
"type": "object",
"properties": {
"fileType": {"type": "string", "format": "uri"}
},
"links": [{
"rel": "describedby",
"href": "{+fileType}"
}]
}
So here, it takes the value from "fileType" and uses it to calculate a link with relation "describedby" - which means "the schema at this location also describes the current data".
The problem is that most validators do not take any notice of any links (including "describedby" ones). You need to find a "hyper-validator" that does.
UPDATE: the tv4 library has added this as a feature
I think cloudfeet answer is a valid solution. You could also use the same approach described here.
You would have a file object type which could be "anyOf" all the subtypes you want to define. You would use an enum in order to be able to reference and validate against each of the subtypes.
If the sub-types schemas are in the same Json-Schema file you don't need to reference the uri explicitly with the "$ref". A correct draft4 validator will find the enum value and will try to validate against that "subschema" in the Json-Schema tree.
In draft5 (in progress) a "switch" statement has been proposed, which will allow to express alternatives in a more explicit way.