Source schema validation rules

Is Invalid Syntax

Error Code

IS_INVALID_SYNTAX

Formal Specification

(to be completed)

Explanatory Text

The @is directive’s field argument must be syntactically valid GraphQL. If
the selection map string is malformed (e.g., missing closing braces, unbalanced quotes, invalid
tokens), then the schema cannot be composed correctly. In such cases, the error
IS_INVALID_SYNTAX is raised.

Examples

In the following example, the @is directive’s field argument is a valid selection
map and satisfies the rule.

type Query {
  personById(id: ID! @is(field: "id")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

In the following counter-example, the @is directive’s field argument has invalid syntax
because it is missing a closing brace.

type Query {
  personById(id: ID! @is(field: "{ id ")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

Is Invalid Field Type

Error Code

IS_INVALID_FIELD_TYPE

Formal Specification

(to be completed)

Explanatory Text

When using the @is directive, the field argument must always be a string that
describes how the arguments can be mapped from the entity type that the lookup field resolves.
If the field argument is provided as a type other than a string (such as an integer,
boolean, or enum), the directive usage is invalid and will cause schema composition to fail.

Examples

In the following example, the @is directive’s field argument is a valid string
and satisfies the rule.

type Query {
  personById(id: ID! @is(field: "id")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

Since field is set to 123 (an integer) instead of a string, this violates the rule
and triggers an IS_INVALID_FIELD_TYPE error.

type Query {
  personById(id: ID! @is(field: 123)): Person @lookup
}

type Person {
  id: ID!
  name: String
}

Is Invalid Usage

Error Code

IS_INVALID_USAGE

Formal Specification

(to be completed)

Explanatory Text

When using the @is directive, the field declaring the argument must be a lookup field
(i.e. have the @lookup directive applied).

Examples

In the following example, the @is directive is applied to an argument declared on a
field with the @lookup directive, satisfying the rule.

type Query {
  personById(id: ID! @is(field: "id")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

In the following counter-example, the @is directive is applied to an argument declared on a
field without the @lookup directive, violating the rule.

type Query {
  personById(id: ID! @is(field: "id")): Person
}

type Person {
  id: ID!
  name: String
}

Post-merge validation rules

Is Invalid Field

Error Code

IS_INVALID_FIELD

Formal Specification

(to be completed)

Explanatory Text

Even if the field selection map for @is(field: "…") is syntactically valid, its contents
must also be valid within the composed schema. Fields must exist on the parent type for them to
be referenced by @is. In addition, fields referencing unknown fields break the valid
usage of @is, leading to an IS_INVALID_FIELD error.

Examples

In the following example, the @is directive’s field argument is a valid field
selection map and satisfies the rule.

# Schema A
type Query {
  personById(id: ID! @is(field: "id")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

In this counter-example, the @is directive references a field (unknownField) that does
not exist on the return type (Person), causing an IS_INVALID_FIELD error.

# Schema A
type Query {
  personById(id: ID! @is(field: "unknownField")): Person @lookup
}

type Person {
  id: ID!
  name: String
}

Add validation rules for @is #177

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Add validation rules for `@is` #177