graphql-cost-guardian

Analyze and limit the cost of GraphQL queries using configurable field costs

Install

npm install graphql-cost-guardian graphql

Usage

import analyzeCost from 'graphql-cost-guardian';

const result = analyzeCost(`
	query {
		users {
			name
			posts {
				title
				comments {
					body
				}
			}
		}
	}
`, {
	fieldCosts: {'Query.users': 10},
	maxCost: 100,
	maxDepth: 5,
});

console.log(result.cost);
// => 14

console.log(result.depth);
// => 4

Middleware

import {createCostMiddleware} from 'graphql-cost-guardian';

const analyze = createCostMiddleware({
	maxCost: 500,
	maxDepth: 10,
	defaultCost: 1,
	listCostFactor: 10,
});

// Use in your GraphQL server middleware
const result = analyze(incomingQuery);

API

analyzeCost(query, options?)

Analyze the cost of a GraphQL query.

query

Type: string

A GraphQL query string.

options

Type: object

fieldCosts

Type: Record<string, number>
Default: {}

Mapping of TypeName.fieldName to custom cost values.

defaultCost

Type: number
Default: 1

Default cost per field when not specified in fieldCosts.

depthCostFactor

Type: number
Default: 1

Multiplier applied per nesting depth level.

listCostFactor

Type: number
Default: 10

Assumed list size multiplier for fields with list-related arguments (first, last, limit).

maxCost

Type: number

Maximum allowed cost. Throws CostExceededError when exceeded.

maxDepth

Type: number

Maximum allowed query depth. Throws DepthExceededError when exceeded.

Return value

Type: {cost: number, depth: number, fields: Map<string, number>}

createCostMiddleware(options)

Returns a function (query) => CostAnalysis with the given options baked in.

CostExceededError

Thrown when query cost exceeds maxCost. Has cost and maxCost properties.

DepthExceededError

Thrown when query depth exceeds maxDepth. Has depth and maxDepth properties.

Related

• graphql — The JavaScript reference implementation for GraphQL

License

MIT