Added multipliers to directiveEstimator, README updates #3

Author: ivome

README.md

@@ -72,13 +72,13 @@ or write your own:
 
 *   **[`simpleEstimator`](src/estimators/simple/README.md):** The simple estimator returns a fixed complexity for each field. Can be used as
     last estimator in the chain for a default value.
-*   **[`fieldConfigEstimator`](src/estimators/simple/README.md):** The field config estimator lets you set a numeric value or a custom estimator
-    function in the field config of your schema. 
 *   **[`directiveEstimator`](src/estimators/directive/README.md):** Set the complexity via a directive in your 
     schema definition (for example via GraphQL SDL)
+*   **[`fieldConfigEstimator`](src/estimators/simple/README.md):** The field config estimator lets you set a numeric value or a custom estimator
+    function in the field config of your schema. 
 *   **[`legacyEstimator`](src/estimators/legacy/README.md):** The legacy estimator implements the logic of previous versions. Can be used
     to gradually migrate your codebase to new estimators. 
-*   PR welcome...
+*   PRs welcome...
 
 Consult the documentation of each estimator for information about how to use them. 
 
@@ -131,4 +131,4 @@ app.use('/api', graphqlHTTP(async (request, response, {variables}) => ({
 This project is inspired by the following prior projects: 
 
 -   Query complexity analysis in the [Sangria GraphQL](http://sangria-graphql.org/) implementation.
-
+-   [graphql-cost-analysis](https://github.com/pa-bru/graphql-cost-analysis) - Multipliers and directiveEstimator

package.json

@@ -16,7 +16,9 @@
   "directories": {
     "lib": "./dist"
   },
-  "dependencies": {},
+  "dependencies": {
+    "lodash.get": "^4.4.2"
+  },
   "peerDependencies": {
     "graphql": "^0.13.2"
   },
@@ -25,7 +27,7 @@
     "README.md",
     "LICENSE"
   ],
-  "repository": "ivome/graphql-query-complexity",
+  "repository": "slicknode/graphql-query-complexity",
   "keywords": [
     "graphql",
     "query complexity"
@@ -36,6 +38,7 @@
     "@types/assert": "^0.0.31",
     "@types/chai": "^4.1.4",
     "@types/graphql": "^0.13.4",
+    "@types/lodash.get": "^4.4.4",
     "@types/mocha": "^5.2.5",
     "chai": "^4.1.0",
     "eslint": "^5.4.0",

src/estimators/directive/README.md

@@ -26,7 +26,31 @@ Define your schema and add the complexity directive:
 
 ```graphql
 type Query {
-  # Set the complexity values on the fields via the directive
+  # Fixed complexity of 5
   someField: String @complexity(value: 5)
+  
+  # Multiply the complexity of the field with a numeric input value
+  # If limit=2 this would result in a complexity of 4
+  listScalar(limit: Int): String @complexity(value: 2, multipliers: ["limit"])
+  
+  # Use a multiplier that is nested in a by defining the multiplier with path notation (see library lodash.get)
+  multiLevelMultiplier(filter: Filter): String @complexity(value: 1, multipliers: ["filter.limit"])
+  
+  # If the multiplier is an array, it uses the array length as multiplier
+  arrayLength(ids: [ID]): String @complexity(value: 1, multipliers: ["ids"])
+  
+  # Using multipliers on fields with composite types calculates the complexity as follows: 
+  # (value + childComplexity) * multiplier1 [... * multiplier2]
+  compositeTypes(ids: [ID]): ChildType @complexity(value: 2, multipliers: ["ids"])
+}
+
+type ChildType {
+  a: String @complexity(value: 1)
+}
+
+input Filter {
+  limit: Int
 }
 ```
+
+The multipliers can be combined. Configured multipliers that don't have a value or `NULL` are ignored. 

src/estimators/directive/__tests__/directiveEstimator-test.ts

@@ -97,4 +97,130 @@ describe('directiveEstimator analysis', () => {
     visit(ast, visitWithTypeInfo(typeInfo, visitor));
     expect(visitor.complexity).to.equal(1);
   });
+
+  it('returns value + child complexity for configured multipliers but no values', () => {
+    const ast = parse(`
+      query {
+        childList {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(5);
+  });
+
+  it('uses numeric multiplier value', () => {
+    const ast = parse(`
+      query {
+        childList(limit: 2) {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(10);
+  });
+
+  it('combines multiple numeric multiplier values', () => {
+    const ast = parse(`
+      query {
+        childList(limit: 2, first: 2) {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(20);
+  });
+
+  it('uses multiplier array value length', () => {
+    const ast = parse(`
+      query {
+        childList(ids: ["a", "b"]) {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(10);
+  });
+
+  it('uses nested multiplier paths', () => {
+    const ast = parse(`
+      query {
+        childList(filter: {limit: 3}) {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(15);
+  });
+
+  it('uses multi level nested multiplier paths with array reference', () => {
+    const ast = parse(`
+      query {
+        childList(filter: {filters: [{limit: 2}]}) {
+          scalar
+        }
+      }
+    `);
+
+    const context = new ValidationContext(schema, ast, typeInfo);
+    const visitor = new ComplexityVisitor(context, {
+      maximumComplexity: 100,
+      estimators: [
+        directiveEstimator()
+      ]
+    });
+
+    visit(ast, visitWithTypeInfo(typeInfo, visitor));
+    expect(visitor.complexity).to.equal(10);
+  });
 });

src/estimators/directive/__tests__/fixtures/schema.ts

@@ -11,5 +11,25 @@ type Query {
   scalar: String @complexity(value: 5)
   negativeCostScalar: String @complexity(value: -20)
   multiDirective: String @cost(value: 1) @complexity(value: 2)
+  
+  childList(
+    limit: Int, 
+    ids: [ID],
+    first: Int,
+    filter: Filter
+  ): [ChildType] @complexity(
+    value: 3, 
+    multipliers: ["first", "limit", "ids", "filter.limit", "filter.filters.0.limit"]
+  )
+}
+
+input Filter {
+  limit: Int
+  ids: [ID]
+  filters: [Filter]
+}
+
+type ChildType {
+  scalar: String @complexity(value: 2)
 }
 `);

src/estimators/directive/index.ts

@@ -2,6 +2,7 @@ import {ComplexityEstimator, ComplexityEstimatorArgs} from '../../QueryComplexit
 import {getDirectiveValues, GraphQLInt, GraphQLList, GraphQLNonNull, GraphQLString} from 'graphql';
 import { GraphQLDirective } from 'graphql/type/directives';
 import { DirectiveLocation } from 'graphql/language/directiveLocation';
+import get from 'lodash.get';
 
 export default function (options?: {}): ComplexityEstimator {
   const mergedOptions = {
@@ -28,6 +29,23 @@ export default function (options?: {}): ComplexityEstimator {
 
   return (args: ComplexityEstimatorArgs) => {
     const values = getDirectiveValues(directive, args.field.astNode);
-    return values.value + args.childComplexity;
+
+    // Get multipliers
+    let totalMultiplier = 1;
+    if (values.multipliers) {
+      totalMultiplier = values.multipliers.reduce((aggregated: number, multiplier: string) => {
+        const multiplierValue = get(args.args, multiplier);
+
+        if (typeof multiplierValue === 'number') {
+          return aggregated * multiplierValue;
+        }
+        if (Array.isArray(multiplierValue)) {
+          return aggregated * multiplierValue.length;
+        }
+        return aggregated;
+      }, totalMultiplier);
+    }
+
+    return (values.value + args.childComplexity) * totalMultiplier;
   };
 }

src/estimators/fieldConfig/README.md

@@ -7,11 +7,18 @@ the estimator does not return any value and the next estimator in the chain is e
 ## Usage
 
 ```typescript
-import queryComplexity, {fieldConfigEstimator} from 'graphql-query-complexity';
+import queryComplexity, {
+  fieldConfigEstimator,
+  simpleEstimator
+} from 'graphql-query-complexity';
 
 const rule = queryComplexity({
   estimators: [
-    fieldConfigEstimator()
+    fieldConfigEstimator(),
+    
+    // We use the simpleEstimator as fallback so we only need to 
+    // define the complexity for non 1 values (this is not required...)
+    simpleEstimator({defaultComplexity: 1})
   ]
   // ... other config
 });

yarn.lock

@@ -14,6 +14,16 @@
   version "0.13.4"
   resolved "https://registry.yarnpkg.com/@types/graphql/-/graphql-0.13.4.tgz#55ae9c29f0fd6b85ee536f5c72b4769d5c5e06b1"
 
+"@types/lodash.get@^4.4.4":
+  version "4.4.4"
+  resolved "https://registry.yarnpkg.com/@types/lodash.get/-/lodash.get-4.4.4.tgz#34b67841594e4ddc8853341d65e971a38cb4e2f0"
+  dependencies:
+    "@types/lodash" "*"
+
+"@types/lodash@*":
+  version "4.14.116"
+  resolved "https://registry.yarnpkg.com/@types/lodash/-/lodash-4.14.116.tgz#5ccf215653e3e8c786a58390751033a9adca0eb9"
+
 "@types/mocha@^5.2.5":
   version "5.2.5"
   resolved "https://registry.yarnpkg.com/@types/mocha/-/mocha-5.2.5.tgz#8a4accfc403c124a0bafe8a9fc61a05ec1032073"
@@ -553,6 +563,10 @@ levn@^0.3.0, levn@~0.3.0:
     prelude-ls "~1.1.2"
     type-check "~0.3.2"
 
+lodash.get@^4.4.2:
+  version "4.4.2"
+  resolved "https://registry.yarnpkg.com/lodash.get/-/lodash.get-4.4.2.tgz#2d177f652fa31e939b4438d5341499dfa3825e99"
+
 lodash.unescape@4.0.1:
   version "4.0.1"
   resolved "https://registry.yarnpkg.com/lodash.unescape/-/lodash.unescape-4.0.1.tgz#bf2249886ce514cda112fae9218cdc065211fc9c"