then : Schema
then
SchemaWhen if is present, and the instance successfully validates against its subschema, then validation succeeds if the instance also successfully validates against this keyword’s subschema.
| Value |
This keyword must be set to a valid JSON Schema
Hint: Use the jsonschema metaschema and jsonschema lint commands to catch keywords set to invalid values
|
|---|---|
| Kind | Applicator |
| Applies To | Any |
| Base Dialect | Draft 7 |
| Changed In | None |
| Introduced In | Draft 7 |
| Vocabulary | Validation |
| Specification | https://json-schema.org/draft-07/draft-handrews-json-schema-validation-01#rfc.section.6.6.2 |
| Metaschema | http://json-schema.org/draft-07/schema# |
| Official Tests | draft7/if-then-else.json |
| Default |
{}
|
| Annotation | None |
| Affected By |
|
| Affects | None |
| Also See |
|
The then keyword restricts instances
to validate against the given subschema if the if sibling keyword successfully validated against the
instance.
Common Pitfall
This keyword has no effect if the if keyword is not declared within the same
subschema.
Best Practice
The if,
then, and else keywords can be thought of as imperative variants
of the anyOf keyword, and both
approaches are equally capable of describing arbitrary conditions. Choose the
one that more elegantly describes your desired
constraints.
Examples
A schema that constrains numeric instances to be positive when they are even numbers
Schema
{
"$schema": "http://json-schema.org/draft-07/schema#",
"if": { "multipleOf": 2 },
"then": { "minimum": 0 }
}
Valid
An even number value that is positive is valid
Instance
10
Invalid
An even number value that is negative is invalid
Instance
-2
Valid
An odd number value that is positive is valid
Instance
7
Valid
An odd number value that is negative is valid
Instance
-3
Valid
A non-number value is valid
Instance
"Hello World"
A schema that uses a title for even numbers
Schema
{
"$schema": "http://json-schema.org/draft-07/schema#",
"if": { "multipleOf": 2 },
"then": { "title": "The value is an even number" }
}
Valid
An even number value is valid
Instance
10
Valid
An odd number value is valid
Instance
5