I am trying to have JSON validation based on the following input:
{
"elements":[
{
"..."
"isSelected": true
},
{
"..."
"isSelected": false
},
{
"..."
"isSelected": false
}
]
}
The input is going to be valid if and only if we have "isSelected" set to "true" (and all the rest set to "false"). Can't have "isSelected: true" more than once (and all the rest need to be "false").
Tried with the following:
{
"$schema": "http://json-schema.org/draft-07/schema#",
"type": "object",
"definitions": {
"element":{
"type": "object",
"properties": {
"isSelected": {
"type": "boolean"
}
}
}
},
"properties": {
"elements": {
"type": "array",
"items": {
"$ref": "#/definitions/element"
},
"oneOf": [
{
"isSelected": true
}
]
}
},
}
unfortunately I don't think this is possible with json schema draft 7. the newest draft (2019-09) features the maxContains keyword, which would be able to validate this, but tooling for this draft is sparse so far. I don't know the tooling you're using, but if you are able to use 2019-09, the schema for 'elements' would look something like:
{
"type": "array",
"contains": {
"properties": {
"isSelected": {"const": true}
}
},
"maxContains": 1
}
oneOf isn't what you're looking for, for this - it checks that one of a set of schemas validates against the instance, not whether one of a set of instances validates against a schema.
This is not currently supported, but you may be interested in this proposal which intends to add a keyword to support key-based item uniqueness. It's not exactly the same, but I think it's related.
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.
Running ajv-cli as part of my automated testing scripts to make sure my mock data is up to date.
./node_modules/.bin/ajv -s ./test-data/manifest.schema.json -d ./test-data/fleet.manifest.json
./test-data/fleet.manifest.json valid
But the data isn't valid.
manifest.schema.json:
{
"$schema": "http://json-schema.org/draft-07/schema#",
"definitions": {
"ManifestHistoryItem": {
"properties": {
"id": {
"default": [
"assetCatalog",
"Roster"
],
"items": {
"type": "string"
},
"type": "array"
},
"name": {
"default": "",
"type": "string"
}
},
"required": [
"id",
"name"
],
"type": "object"
}
}
}
fleet.manifest.json:
{
"namee": "Epic Space Battles"
}
(it's missing the required "id" property, and "name" is misspelled)
Schema is generated from "typescript-json-schema": "^0.54.0" from a typescript model and evaluated via "ajv-cli": "^5.0.0".
Your schema declares definitions, but it doesn't reference them anywhere. You need to add a "$ref": "#/definitions/ManifestHistoryItem" at the root.
{
"definitions": {
"ManifestHistoryItem": { ... }
},
"$ref": "#/definitions/ManifestHistoryItem"
}
Either that or you can just get rid of the definitions wrapper altogether and just have the { ... } part from above.
Effectively what's happening is you've defined an empty schema, which applies no constraints, meaning all instances (data) pass.
I want to set up the conditional validation in my schema. I saw an example here on SO.
I have a similar setup, where I would like to validate if the field public is set to string "public". If it is set to "public" then I want to make fields description, attachmentUrl and tags required. If the field is not set to "public" then this fields are not required.
{
"$schema": "http://json-schema.org/draft-04/schema#",
"title": "Update todo",
"type": "object",
"properties": {
"public": {
"type": "string"
},
"description": {
"type": "string",
"minLength": 3
},
"tags": {
"type": "array",
"items": {
"type": "string"
},
"uniqueItems": true,
"minItems": 1
},
"attachmentUrl": {
"type": "string"
}
},
"anyOf": [
{
"not": {
"properties": {
"public": { "const": "public" }
},
"required": ["public"]
}
},
{ "required": ["description", "tags", "attachmentUrl"] }
],
"additionalProperties": false
}
But, when I try to deploy it like that, I get the following error:
Invalid model specified: Validation Result: warnings : [], errors :
[Invalid model schema specified. Unsupported keyword(s): ["const"]]
The "const" keyword wasn't added until draft 06. You should upgrade to an implementation that supports at least that version.
https://json-schema.org/draft-06/json-schema-release-notes.html#additions-and-backwards-compatible-changes
Otherwise, you can use "enum" with a single value: "enum": ["public"]
Consider an API with an endpoint in which you pass a parameter foo as part of the URL-path, and pass some parameters as json in the body of a POST request.
This uri parameter foo must have one of the values fooBar and fooBaz. Otherwise the request gest a 404.
If the value of foo is fooBar then the body attribute bar is required.
If the value of foo is fooBaz then the body attribute baz is required.
How do I specify a jsonSchema for such an endpoint?
An example for such a request would be:
POST /path/to/endpoint/fooBar HTTP/1.1
Accept: application/json
Content-Type: application/json
Content-Length: 20
{"bar":"something"}
So far I came up with the following based on this and that but I have no idea if this is correct.
{
"$schema": "http://json-schema.org/draft-03/schema#",
"id": "http://json-schema.org/draft-03/schema#",
"definitions": {
"foo": { "enum": ["fooBar", "fooBaz"] }
},
"type": "object",
"properties": {
"foo": { "$ref": "#/definitions/foo" },
"bar": { "type": "string" },
"baz": { "type": "string" }
},
"links": [{
"rel": "self",
"href": "/path/to/endpoint/{foo}",
"hrefSchema": {
"properties": {
"foo": {"$ref": "#/definitions/foo"}
}
}
}],
"anyOf": [
{
"properties": {
"foo": { "enum": ["fooBar"] }
},
"required": ["bar"]
},
{
"properties": {
"foo": { "enum": ["fooBaz"] }
},
"required": ["baz"]
},
]
}
JSON Schema validation is not aware of the URI that the data being validated came from (if any). You can use JSON Hyper-Schema to tell your users how to send that data in the way you expect, but you will still need to do an additional check on the server-side to validate that the request was sent properly.
Before I get into the solution, I want to point out a couple things. Your $schema is set to "draft-03". If you really need "draft-03", this solution won't work. anyOf, allOf and the array form of required were added in "draft-04". hrefSchema was added in "draft-06". Since "draft-06" is brand new and is not well supported yet and you don't need hrefSchema anyway, I'm going to assume "draft-04" ("draft-05" was effectively skipped).
The next thing to mention is that you are using id wrong. It should be the identifier for your schema. You usually don't need this, but if you do, it should be the full URI identifying your schema. That is how my solution uses it.
Last thing before I get into the solution. If you are using the link keyword, you are using JSON Hyper-Schema and your $schema should reflect that. It should have "hyper-schema" instead of "schema" at the end of the URI.
Now the solution. I broke it into two parts, the schema that you put through the validator and the hyper-schema that tells users how to make the request. You've got the first one right. I only fixed the $schema and id.
{
"$schema": "http://json-schema.org/draft-04/schema#",
"id": "http://example.com/schema/my-foo-schema",
"type": "object",
"properties": {
"foo": { "enum": ["fooBar", "fooBaz"] },
"bar": { "type": "string" },
"baz": { "type": "string" }
},
"anyOf": [
{
"properties": {
"foo": { "enum": ["fooBar"] }
},
"required": ["bar"]
},
{
"properties": {
"foo": { "enum": ["fooBaz"] }
},
"required": ["baz"]
}
]
}
Next is the hyper-schema. You can't reference anything external (href, instance data) in a request schema, but you can write your schema so that it matches your href. The duplication is unfortunate, but that's the way you have to do it.
{
"$schema": "http://json-schema.org/draft-04/hyper-schema#",
"links": [
{
"rel": "http://example.com/rel/my-foo-relation",
"href": "/path/to/endpoint/fooBar",
"method": "POST",
"schema": {
"allOf": [{ "$ref": "http://example.com/schema/my-foo-schema" }],
"properties": {
"foo": { "enum": ["fooBar"] }
}
}
},
{
"rel": "http://example.com/rel/my-foo-relation",
"href": "/path/to/endpoint/fooBaz",
"method": "POST",
"schema": {
"allOf": [{ "$ref": "http://example.com/schema/my-foo-schema" }],
"properties": {
"foo": { "enum": ["fooBaz"] }
}
}
},
{
"rel": "self",
"href": "/path/to/endpoint"
}
]
}
Usually when I come across something that is difficult to model with hyper-schema, it means that I am doing something overly complicated with my API and I need to refactor. I suggest taking a few minutes to think about alternative designs where this switching on an enum isn't necessary.
For example a schema for a file system, directory contains a list of files. The schema consists of the specification of file, next a sub type "image" and another one "text".
At the bottom there is the main directory schema. Directory has a property content which is an array of items that should be sub types of file.
Basically what I am looking for is a way to tell the validator to look up the value of a "$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.