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37 lines
1.1 KiB
37 lines
1.1 KiB
// @flow strict
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import { GraphQLError } from '../../error/GraphQLError';
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import type { ASTVisitor } from '../../language/visitor';
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import type { VariableDefinitionNode } from '../../language/ast';
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import type { ASTValidationContext } from '../ValidationContext';
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/**
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* Unique variable names
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*
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* A GraphQL operation is only valid if all its variables are uniquely named.
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*/
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export function UniqueVariableNamesRule(
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context: ASTValidationContext,
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): ASTVisitor {
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let knownVariableNames = Object.create(null);
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return {
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OperationDefinition() {
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knownVariableNames = Object.create(null);
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},
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VariableDefinition(node: VariableDefinitionNode) {
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const variableName = node.variable.name.value;
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if (knownVariableNames[variableName]) {
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context.reportError(
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new GraphQLError(
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`There can be only one variable named "$${variableName}".`,
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[knownVariableNames[variableName], node.variable.name],
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),
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);
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} else {
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knownVariableNames[variableName] = node.variable.name;
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}
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},
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};
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}
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