I have a property in my JSON schema like this:
"properties": {
"theme": {
"type": "boolean",
"title": "Theme",
"enum": ["Light", "Dark"]
}
}
This property is stored in my database table as a boolean, with 1 for light, 0 for dark. The problem is that when I fill out the form generated by the schema it errors, telling me that the value of root.theme must be one of [true, false] and won't proceed to my backend handler.
There is a solution I found that I'm currently utilising, which is changing the "type" to string, and handling it on the backend side, by converting the string value I receive into the boolean corresponding to it.
I am wondering whether JSON schema natively supports custom naming for true & false in a boolean property.
This is not possible as of draft-7 (current at time of writing)
Related
Just started with jsonschema. I want to describe a collection of objects for a property where the key may not be known a priori.
Here is my starting point:
"tx_properties": {
"type": "object",
"anyOf": [
{
"required": [
"original_msg"
]
}
],
"properties": {
"original_msg": {
"type": "string"
}
}
}
}
I want to be able to validate the additions of more properties for tx_properties that may have different types but are not known at schema definition time.
For example I might have, in json:
"tx_properties": {
"original_msg": "foo",
"something_else": "bar",
"or_something_numeric": 172,
"or_even_deeper_things": {
"fungible": false,
}
}
As a n00b I'm a bit stuck on how to accomplish this. The use of anyOne is what I thought I needed at least in the final solution.
As #Evert said, "additionalProperties": false can be used to indicate that no other properties other than those listed in properties keywords (and patternProperties) are permitted. If additionalProperties is omitted, the behaviour is as if the schema said "additionalProperties": true (that is, additional properties are permitted).
Also note that the value at additionalProperties doesn't have to be a boolean: it can be a subschema itself, to allow you to conditionally allow for additional properties depending on their value(s).
Reference: https://json-schema.org/understanding-json-schema/reference/object.html#additional-properties
I have an existing JSON data feed between multiple systems which I do not control and cannot change. I have been tasked with writing a schema for this feed. The existing JSON looks in part like this:
"ids": [
{ "type": "payroll", "value": "011808237" },
{ "type": "geid", "value": "31826" }
]
When I try to define a JSON schema for this, I wind up with a scrap of schema that looks like this:
"properties": {
"type": { <====================== PROBLEM!!!!
"type": "string",
"enum": [ "payroll", "geid" ]
},
"value": {
"type": [ "string", "null" ],
"pattern": "^[0-9]*$"
}
}
As you might guess, when the JSON validator hits that "type" on the line marked "PROBLEM!!!" it gets upset and throws an error about how type needs to be a string or array.
That's a bug in the particular implementation you're using, and should be reported as such. It should be able to handle properties-that-look-like-keywords just fine. In fact, the metaschema (the schema to valid schemas) uses "type" in exactly this way, along with all the other keywords too: e.g. http://json-schema.org/draft-07/schema
I wonder if it is not making use of the official test suite (https://github.com/json-schema-org/JSON-Schema-Test-Suite)?
You didn't indicate what implementation you're using, or what language, but perhaps you can find an alternative one here: https://json-schema.org/implementations.html#validators
I found at least a work-around if not a proper solution. Instead of "type" inside "properties", use "^type$" inside "patternProperties". I.e.
"patternProperties": {
"^type$": {
"type": "string"
}
}
Unfortunately there doesn't seem to be a great way to make "^type$" a required property. I've settled for listing all the other properties as "required" and setting the min and max property counts to the number that should be there.
I'm going through the docs to try and figure out how loops work so I can validate every object of an array of objects match the schema.
It seems like recursion is what I want but the example given doesn't work: https://json-schema.org/understanding-json-schema/structuring.html
I'm trying to validate that example but its always "valid". I tried changing all the field names in the JSON and it doesn't matter:
Not sure what's happening. For this example how would I validate every child matches the person schema (without statically writing out each one in the schema).
For example, I want to valid this JSON. there could be any number of objects under toplevel and any number of objects under "objectsList". I want to make sure every object under "objectsList" has the right field names and types (again without hard coding the entire thing in the schema):
{
"toplevel": {
"objectOne": {
"objectsList": [
{
"field1": 1231,
"field2": "sekfjlskjflsdf",
"field3": ["ssss","eeee"],
},
{
"field1": 11,
"field2": "sef",
"field3": ["eeee","qqqq"],
},
{
"field1": 1231,
"field2": "wwwww",
"field3": ["sisjflkssss","esdfsdeee"],
},
]
},
"objectTwo": {
"objectsList": [
{
"field1": 99999,
"field2": "yuyuyuyuyu",
"field3": ["ssssuuu","eeeeeee"],
},
{
"field1": 221,
"field2": "vesdlkfjssef",
"field3": ["ewerweeee","ddddq"],
},
]
},
}
}
What's wrong?
The problem here is not the recursion – your schema looks good.
The underlying issue is the same as here: https://stackoverflow.com/a/61038256/5127499
JSON Schema is designed for extensibility. That means it allows any kind of additional properties to be added as long as they are not conflicting with the known/expected keywords.
Solution
The solution here is to add "additionalProperties": false in your "person" (from the screenshot) and top-level schema to prevent those incorrect objects to be accepted. Same goes for your second example: in any definitions of "type": "object" you'd have to add "additionalProperties": false if you don't want to allow these extraneous properties to be defined.
Alternatively, you can declare your expected properties as required to ensure that at least those are present.
Why?
As per json-schema.org/understanding-json-schema (emphasis mine):
The additionalProperties keyword is used to control the handling of extra stuff, that is, properties whose names are not listed in the properties keyword. By default any additional properties are allowed.
The additionalProperties keyword may be either a boolean or an object. If additionalProperties is a boolean and set to false, no additional properties will be allowed.
To address the screenshot you posted and why the instance passes:
The schema is looking to find a person property, but that property doesn't exist.
The schema does not declare that person is required.
The schema does not declare requirements on undefined properties, so it will always accept the personsdfsd property with whatever value is in it, without checking it further.
So in short, your JSON data is bad and your schema doesn't have any protections against that.
Other than that, your schema looks good. It should validate that items in the children property match the person definition's subschema.
I have a system that is receiving JSON messages which contain metadata from a static analysis of a file. The names of these fields are dynamically generated from the scan and can be any valid string, but the value is always a valid string.
e.g.
{
"filename": "hello.txt",
...
"meta": {
"some file property": "any string",
"some other file property": "another string",
...
}
}
I have no way of knowing what the keys in meta will be before receiving the message, nor do I know how many keys there will be. Is there a way of capturing in a JSONSchema that it doesn't matter what keys are present, so long as their values are always strings?
I think you're looking for additionalProperties
Validation with "additionalProperties" applies only to the child
values of instance names that do not match any names in "properties",
and do not match any regular expression in "patternProperties".
The value of additionalProperties can be a JSON Schema, like so
...
"additionalProperties" : {
"type": "string"
}
...
Feel free to let me know if I've missed anything in my explanation, or ask any further questions.
I'm struggling with a REST API design concept. I have these classes:
user:
- first_name
- last_name
metadata_fields:
- field_name
user_metadata:
- user_id
- field_id
- value
- unique index on [user_id, field_id]
Ok, so users have many metadata and the type of metadata is defined in metadata_fields. Typical HABTM with extra data in the join table.
If I were to update user_metadata through a Rails form, the data would look like this:
user_metadata: {
id: 1,
user_id: 2,
field_id: 3,
value: 'foo'
}
If I posted to the user#update controller, the data would look like this:
user: {
user_metadata: {
id: 1,
field_id: 3,
value: 'foo'
}
}
The trouble with this approach is that we're ignoring the uniqueness of the user_id/field_id relationship. If I change the field_id in either update, I'm not just changing data, I'm changing the meaning of that data. This tends to work fine in Rails because it's somewhat of a walled garden, but it breaks down when you open up an API endpoint.
If I allow this:
PATCH /api/user_metadata
Then I'm opening myself up to someone modifying the user_id or field_id or both. Similarly with this:
PATCH /api/user/:user_id/metadata
Now user_id is set but field_id can still change. So really the only way to solve this is to limit the update to a single field:
PATCH /api/user/:user_id/metadata/:field_id
Or a bulk update:
PATCH /api/user/:user_id/metadata
But with that call, we have to modify the data structure so that the uniqueness of the user_id/field_id relationship is intact:
user_metadata: {
field_id1: 'value1',
field_id2: 'value2',
...
}
I'd love to hear thoughts here. I've scoured Google and found absolutely nothing. Any recommendations?
As metadata belongs to a certain user /api/user/{userId}/metadata/{metadataId} is probably the clean URI for a single metadata resource of a user. The URI of your resource is already the unique-key you are looking for. There can't be 2 resources with the same URI! Furthermore, the URI already contains the user and field IDs.
A request like GET /api/user/1 HTTP/1.1 could return a HAL-like representation like the one below:
{
"user" : {
"id": "1",
"firstName": "Max",
"lastName": "Sample",
...
"_links": {
"self" : {
"href": "/api/user/1"
}
},
"_embedded": {
"metadata" : {
"fields" : [{
"id": "1",
"type": "string",
"value": "foo",
"_links": {
"self": {
"href": "/api/user/1/metadata/1"
}
}
}, {
"id": "2",
"type": "string",
"value": "bar",
"_links": {
"self": {
"href": "/api/user/1/metadata/2"
}
}
}],
"_links": {
"self": {
"href": "/api/user/1/metadata"
}
}
}
}
}
}
Of course you could send a PUT or a PATCH request to modify an existing metadata field. Though, the URI of the resource will still be the same (unless you move or delete a resource within a PATCH request).
You also have the possibility to ignore certain fields on incomming PUT requests which prevents modification of certain fields like id or _link. I'll assume this should also be valid for PATCH requests, though will have to re-read the spec again therefore.
Therefore, I'd suggest to ignore any id or _link fields contained in requests and update the remaining fields. But you also have the option to return a 403 Forbidden or 409 Conflict response if someone tries to update an ID-field.
UPDATE
If you want to update multiple fields within a single request, you have two options:
Using PUT and replace the current set of fields with the new version
Using PATCH and send the server the necessary steps to transform the current field-set to the new field-set
Example PUT:
PUT /api/user/1/metadata HTTP/1.1
{
"metadata": {
"fields": [{
"type": "string",
"value": "newFoo"
}, {
"type": "string",
"value": "newBar"
}]
}
}
This request would first delete every stored metadata field of the user the metadata belong to and afterwards create a new resoure for each contained field in the request. While this still guarantees unique URIs, there are a couple of drawbacks to this approach however:
all the data which should be available after the update, even fields that do not change, need to be transmitted
clients which have a URI pointing to a certain resource may point to a false representation. F.e. a client has retrieved /user/1/metadata/2right before a further client updated all the metadata, the IDs are dispatched via auto-increment, the update however introduced a new second item and therefore moved the former 2 to position 3, client1 has now a reference to /user/1/metadata/2 while the actual data is /user/1/metadata/3 however. To prevent this, unique UUIDs could be used instead of autoincrement IDs. If client 1 later on tries to retrieve or update former resource 2, his can be notified that the resource is not available anymore, even a redirect to the new location could be created.
Example PATCH:
A PATCH request contains the necessary steps to transform the state of a resource to the new state. The request itself can affect multiple resources at the same time and even create or delete other resources as needed.
The following example is in json-patch+json format:
PATCH /api/user/1/metadata HTTP/1.1
[
{
"op": "add",
"path": "/0/value",
"value": "newFoo"
},
{
"op": "add",
"path": "/2",
"value": { "type": "string", "value": "totally new entry" }
},
{
"op": "remove",
"path": "/1"
},
]
The path is defined as a JSON Pointer for the invoked resource.
The add operation of the JSON-Patch type is defined as:
If the target location specifies an array index, a new value is inserted into the array at the specified index.
If the target location specifies an object member that does not already exist, a new member is added to the object.
If the target location specifies an object member that does exist, that member's value is replaced.
For the removal case however, the spec states:
If removing an element from an array, any elements above the specified index are shifted one position to the left.
Therefore the newly added entry would end up in position 2 in the array. If not an auto-increment value is used for the ID, this should not be a big problem though.
Besindes add, and remove the spec also contains definitions for replace, move, copy and test.
The PATCH should be transactional - either all operations succeed or none. The spec states:
If a normative requirement is violated by a JSON Patch document, or if an operation is not successful, evaluation of the JSON Patch document SHOULD terminate and application of the entire patch document SHALL NOT be deemed successful.
I'll interpret this lines as, if it tries to update a field which it is not supposed to update, you should return an error for the whole PATCH request and therefore do not alter any resources.
Drawback to the PATCH approach is clearly the transactional requirement as well as the JSON Pointer notation, which might not be that popular (at least I haven't used it often and had to look it up again). Same as with PUT, PATCH allows to add new resources inbetween existing resources and shifting further ones to the right which may lead to an issue if you rely on autoincrement values.
Therefore, I strongly recommend to use randomly generated UUIDs as identifier rather than auto-increment values.