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/** @category Validation Rules */
import { inspect } from '../../jsutils/inspect.mjs';
import { GraphQLError } from '../../error/GraphQLError.mjs';
import { getNamedType, isLeafType } from '../../type/definition.mjs';
/**
* Scalar leafs
*
* A GraphQL document is valid only if all leaf fields (fields without
* sub selections) are of scalar or enum types.
* @param context - The validation context used while checking the document.
* @returns A visitor that reports validation errors for this rule.
* @example
* ```ts
* import { buildSchema, parse, validate } from 'graphql';
* import { ScalarLeafsRule } from 'graphql/validation';
*
* const schema = buildSchema(`
* type Query {
* name: String
* }
* `);
*
* const invalidDocument = parse(`
* { name { length } }
* `);
* const invalidErrors = validate(schema, invalidDocument, [ScalarLeafsRule]);
*
* invalidErrors.length; // => 1
*
* const validDocument = parse(`
* { name }
* `);
* const validErrors = validate(schema, validDocument, [ScalarLeafsRule]);
*
* validErrors; // => []
* ```
*/
export function ScalarLeafsRule(context) {
return {
Field(node) {
const type = context.getType();
const selectionSet = node.selectionSet;
if (type) {
if (isLeafType(getNamedType(type))) {
if (selectionSet) {
const fieldName = node.name.value;
const typeStr = inspect(type);
context.reportError(
new GraphQLError(
`Field "${fieldName}" must not have a selection since type "${typeStr}" has no subfields.`,
{
nodes: selectionSet,
},
),
);
}
} else if (!selectionSet) {
const fieldName = node.name.value;
const typeStr = inspect(type);
context.reportError(
new GraphQLError(
`Field "${fieldName}" of type "${typeStr}" must have a selection of subfields. Did you mean "${fieldName} { ... }"?`,
{
nodes: node,
},
),
);
} else if (selectionSet.selections.length === 0) {
const fieldName = node.name.value;
const typeStr = inspect(type);
context.reportError(
new GraphQLError(
`Field "${fieldName}" of type "${typeStr}" must have at least one field selected.`,
{
nodes: node,
},
),
);
}
}
},
};
}