Validate phone only when provided using Json Schema - jsonschema

Question

Using following JSON schema to validate phone number if provided.
Accepted validation
Min length 10
Max length 20
and Pattern
If phone is null or empty, no validation is required
{
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"Item": {
"type": "object",
"properties": {
"Phone": {
"anyOf": [
{
"type": "integer",
"minLength": 10,
"maxLength": 20,
"pattern": "^(\\([0-9]{3}\\))?[0-9]{3}-[0-9]{4}$"
},
{
"type": [ "integer", "null" ]
}
]
}
}
}
}
}
Can you please suggest what is missing in the above schema?
Thank you!

Answer 1

Remove integer from the null case. It's slowing so integers through, which overrides the phone number case.
Secondarily, if possible, you may want to use a later draft for your schema. Draft 4 is quite old. Check with your validator to see if it supports a newer draft.

Answer 2

There are errors in your schema, but you're missing the understanding about how JSON Schema works in terms of applicability.
JSON Schema has many keywords that are only applicable to a specific type. When the type is not that of a keywords applicability, it has no effect.
The subschema for "phone" can be simplified as the following:
{
"type": ["string", "null"],
"minLength": 10,
"maxLength": 20,
"pattern": "^(\\([0-9]{3}\\))?[0-9]{3}-[0-9]{4}$"
}
The keywords minLenght, maxLength, and pattern are only applicable to strings. If the value is not a string (and is null), those keywords are not applicable, and so are ignored.
(I've not checked your regex here, just copied what you had already.)