fix: #43 floating point issue in multipleOf validation

- fix multipleOf validation logic
- remove floatingPointPrecision setting

Author: Sascha Goldhofer

dist/jsonSchemaLibrary.js

@@ -1,7 +1,6 @@
 declare const _default: {
     DECLARATOR_ONEOF: string;
     GET_TEMPLATE_RECURSION_LIMIT: number;
-    floatingPointPrecision: number;
     propertyBlacklist: string[];
     templateDefaultOptions: {
         addOptionalProps: boolean;

dist/lib/config/settings.d.ts

@@ -0,0 +1,4 @@
+/**
+ * returns the floating point precision of a decimal number or 0
+ */
+export declare function getPrecision(value: number): number;

dist/lib/utils/getPrecision.d.ts

@@ -1,7 +1,6 @@
 export default {
     DECLARATOR_ONEOF: "oneOfProperty",
     GET_TEMPLATE_RECURSION_LIMIT: 1,
-    floatingPointPrecision: 10000,
     propertyBlacklist: ["_id"],
     templateDefaultOptions: {
         addOptionalProps: false,

dist/module/lib/config/settings.js

@@ -0,0 +1,8 @@
+/**
+ * returns the floating point precision of a decimal number or 0
+ */
+export function getPrecision(value) {
+    const string = `${value}`;
+    const index = string.indexOf(".");
+    return index === -1 ? 0 : string.length - (index + 1);
+}

dist/module/lib/utils/getPrecision.js

@@ -7,8 +7,8 @@ import { validateAllOf } from "../features/allOf";
 import { validateAnyOf } from "../features/anyOf";
 import { validateDependencies } from "../features/dependencies";
 import { validateOneOf } from "../features/oneOf";
+import { getPrecision } from "../utils/getPrecision";
 import deepEqual from "fast-deep-equal";
-const FPP = settings.floatingPointPrecision;
 const hasOwnProperty = Object.prototype.hasOwnProperty;
 const hasProperty = (value, property) => !(value[property] === undefined || !hasOwnProperty.call(value, property));
 // list of validation keywords: http://json-schema.org/latest/json-schema-validation.html#rfc.section.5
@@ -283,12 +283,24 @@ const KeywordValidation = {
         return undefined;
     },
     multipleOf: (draft, schema, value, pointer) => {
-        if (isNaN(schema.multipleOf)) {
+        if (isNaN(schema.multipleOf) || typeof value !== "number") {
             return undefined;
         }
-        // https://github.com/cfworker/cfworker/blob/master/packages/json-schema/src/validate.ts#L1061
-        // https://github.com/ExodusMovement/schemasafe/blob/master/src/compile.js#L441
-        if (((value * FPP) % (schema.multipleOf * FPP)) / FPP !== 0) {
+        const valuePrecision = getPrecision(value);
+        const multiplePrecision = getPrecision(schema.multipleOf);
+        if (valuePrecision > multiplePrecision) {
+            // higher precision of value can never be multiple of value
+            return draft.errors.multipleOfError({
+                multipleOf: schema.multipleOf,
+                value,
+                pointer,
+                schema
+            });
+        }
+        const precision = Math.pow(10, multiplePrecision);
+        const val = Math.round(value * precision);
+        const multiple = Math.round(schema.multipleOf * precision);
+        if ((val % multiple) / precision !== 0) {
             return draft.errors.multipleOfError({
                 multipleOf: schema.multipleOf,
                 value,

dist/module/lib/validation/keyword.js

@@ -1,7 +1,6 @@
 export default {
     DECLARATOR_ONEOF: "oneOfProperty",
     GET_TEMPLATE_RECURSION_LIMIT: 1,
-    floatingPointPrecision: 10000,
     propertyBlacklist: ["_id"],
     templateDefaultOptions: {
         addOptionalProps: false,

lib/config/settings.ts

@@ -24,7 +24,6 @@ export default function getChildSchemaSelection(
     }
 
     const result = draft.step(property, schema, {}, "#");
-
     if (isJsonError(result)) {
         return result;
     }

lib/getChildSchemaSelection.ts

@@ -0,0 +1,8 @@
+/**
+ * returns the floating point precision of a decimal number or 0
+ */
+export function getPrecision(value: number): number {
+    const string = `${value}`;
+    const index = string.indexOf(".");
+    return index === -1 ? 0 : string.length - (index + 1);
+}

lib/utils/getPrecision.ts

@@ -7,8 +7,8 @@ import { validateAllOf } from "../features/allOf";
 import { validateAnyOf } from "../features/anyOf";
 import { validateDependencies } from "../features/dependencies";
 import { validateOneOf } from "../features/oneOf";
+import { getPrecision } from "../utils/getPrecision";
 import deepEqual from "fast-deep-equal";
-const FPP = settings.floatingPointPrecision;
 
 const hasOwnProperty = Object.prototype.hasOwnProperty;
 const hasProperty = (value: Record<string, unknown>, property: string) =>
@@ -316,20 +316,36 @@ const KeywordValidation: Record<string, JsonValidator> = {
         return undefined;
     },
     multipleOf: (draft, schema, value: number, pointer) => {
-        if (isNaN(schema.multipleOf)) {
+        if (isNaN(schema.multipleOf) || typeof value !== "number") {
             return undefined;
         }
-        // https://github.com/cfworker/cfworker/blob/master/packages/json-schema/src/validate.ts#L1061
-        // https://github.com/ExodusMovement/schemasafe/blob/master/src/compile.js#L441
-        if (((value * FPP) % (schema.multipleOf * FPP)) / FPP !== 0) {
+
+        const valuePrecision = getPrecision(value);
+        const multiplePrecision = getPrecision(schema.multipleOf);
+        if (valuePrecision > multiplePrecision) {
+            // value with higher precision then multipleOf-precision can never be multiple
+            return draft.errors.multipleOfError({
+                multipleOf: schema.multipleOf,
+                value,
+                pointer,
+                schema
+            });
+        }
+
+        const precision = Math.pow(10, multiplePrecision);
+        const val = Math.round(value * precision);
+        const multiple = Math.round(schema.multipleOf * precision);
+        if ((val % multiple) / precision !== 0) {
             return draft.errors.multipleOfError({
                 multipleOf: schema.multipleOf,
                 value,
                 pointer,
                 schema
             });
         }
-        // also check https://stackoverflow.com/questions/1815367/catch-and-compute-overflow-during-multiplication-of-two-large-integers
+
+        // maybe also check overflow
+        // https://stackoverflow.com/questions/1815367/catch-and-compute-overflow-during-multiplication-of-two-large-integers
         return undefined;
     },
     not: (draft, schema, value, pointer) => {

lib/validation/keyword.ts

@@ -0,0 +1,80 @@
+import { expect } from "chai";
+import { Draft07 as Draft } from "../../../lib/draft07";
+
+describe("issue#43 - multipleOf .01", () => {
+    let draft: Draft;
+    beforeEach(() => {
+        draft = new Draft({
+            type: "number",
+            multipleOf: 0.01
+        });
+    });
+
+    it("should validate 1", () => {
+        const result = draft.validate(1);
+        expect(result).to.have.length(0);
+    });
+
+    it("should validate .2", () => {
+        const result = draft.validate(0.2);
+        expect(result).to.have.length(0);
+    });
+
+    it("should validate .02", () => {
+        const result = draft.validate(0.02);
+        expect(result).to.have.length(0);
+    });
+
+    it("should not validate .025", () => {
+        const result = draft.validate(0.025);
+        expect(result).to.have.length(1);
+    });
+
+    it("should validate 1.36", () => {
+        const result = draft.validate(1.36);
+        expect(result).to.have.length(0);
+    });
+
+    it("should validate 2.74", () => {
+        const result = draft.validate(2.74);
+        expect(result).to.have.length(0);
+    });
+
+    it("should validate 123456789", () => {
+        const result = draft.validate(123456789);
+        expect(result).to.have.length(0);
+    });
+
+    it("should not validate Infinity", () => {
+        const result = draft.validate(1e308);
+        expect(result).to.have.length(1);
+    });
+
+    it("should validate all floats with two decimals", () => {
+        for (let i = 0; i <= 100; i++) {
+            let num = `2.${i}`;
+            expect(draft.validate(parseFloat(num))).to.have.length(
+                0,
+                `should have validated '${num}'`
+            );
+        }
+    });
+
+    it("should still validate multiple of integers", () => {
+        draft = new Draft({
+            type: "number",
+            multipleOf: 3
+        });
+        const result = draft.validate(9);
+        expect(result).to.have.length(0);
+    });
+
+    it("should still invalidate non-multiples of integers", () => {
+        draft = new Draft({
+            type: "number",
+            multipleOf: 3
+        });
+        const result = draft.validate(7);
+        expect(result).to.have.length(1);
+    });
+});

test/unit/issues/issue43.multipleOf.float.test.ts

@@ -0,0 +1,11 @@
+import { expect } from "chai";
+import { getPrecision } from "../../../lib/utils/getPrecision";
+
+describe("getPrecision", () => {
+    it("should return decimal precision", () => {
+        expect(getPrecision(1.1)).to.equal(1);
+        expect(getPrecision(0.12)).to.equal(2);
+        expect(getPrecision(0.123)).to.equal(3);
+        expect(getPrecision(123.4567)).to.equal(4);
+    });
+});