Change serialization for Int, Float and Boolean to work with objects (#…

…2382)

It is good to have an opportunity to pass objects which have valueOf() method in resolvers.
For example, I have such objects as "Money", "Price" and so on in my app, and they have valueOf() method which returns a value.

src/type/__tests__/serialization-test.js

@@ -20,6 +20,14 @@ describe('Type System: Scalar coercion', () => {
     expect(GraphQLInt.serialize(1e5)).to.equal(100000);
     expect(GraphQLInt.serialize(false)).to.equal(0);
     expect(GraphQLInt.serialize(true)).to.equal(1);
+    expect(
+      GraphQLInt.serialize({
+        value: 5,
+        valueOf() {
+          return this.value;
+        },
+      }),
+    ).to.equal(5);
 
     // The GraphQL specification does not allow serializing non-integer values
     // as Int to avoid accidental data loss.
@@ -79,6 +87,14 @@ describe('Type System: Scalar coercion', () => {
     expect(GraphQLFloat.serialize('-1.1')).to.equal(-1.1);
     expect(GraphQLFloat.serialize(false)).to.equal(0.0);
     expect(GraphQLFloat.serialize(true)).to.equal(1.0);
+    expect(
+      GraphQLFloat.serialize({
+        value: 5.5,
+        valueOf() {
+          return this.value;
+        },
+      }),
+    ).to.equal(5.5);
 
     expect(() => GraphQLFloat.serialize(NaN)).to.throw(
       'Float cannot represent non numeric value: NaN',
@@ -139,6 +155,14 @@ describe('Type System: Scalar coercion', () => {
     expect(GraphQLBoolean.serialize(0)).to.equal(false);
     expect(GraphQLBoolean.serialize(true)).to.equal(true);
     expect(GraphQLBoolean.serialize(false)).to.equal(false);
+    expect(
+      GraphQLBoolean.serialize({
+        value: true,
+        valueOf() {
+          return this.value;
+        },
+      }),
+    ).to.equal(true);
 
     expect(() => GraphQLBoolean.serialize(NaN)).to.throw(
       'Boolean cannot represent a non boolean value: NaN',

src/type/scalars.js

@@ -22,24 +22,26 @@ const MAX_INT = 2147483647;
 const MIN_INT = -2147483648;
 
 function serializeInt(outputValue: mixed): number {
-  if (typeof outputValue === 'boolean') {
-    return outputValue ? 1 : 0;
+  const coercedValue = serializeObject(outputValue);
+
+  if (typeof coercedValue === 'boolean') {
+    return coercedValue ? 1 : 0;
   }
 
-  let num = outputValue;
-  if (typeof outputValue === 'string' && outputValue !== '') {
-    num = Number(outputValue);
+  let num = coercedValue;
+  if (typeof coercedValue === 'string' && coercedValue !== '') {
+    num = Number(coercedValue);
   }
 
   if (!isInteger(num)) {
     throw new GraphQLError(
-      `Int cannot represent non-integer value: ${inspect(outputValue)}`,
+      `Int cannot represent non-integer value: ${inspect(coercedValue)}`,
     );
   }
   if (num > MAX_INT || num < MIN_INT) {
     throw new GraphQLError(
       'Int cannot represent non 32-bit signed integer value: ' +
-        inspect(outputValue),
+        inspect(coercedValue),
     );
   }
   return num;
@@ -84,17 +86,20 @@ export const GraphQLInt = new GraphQLScalarType({
 });
 
 function serializeFloat(outputValue: mixed): number {
-  if (typeof outputValue === 'boolean') {
-    return outputValue ? 1 : 0;
+  const coercedValue = serializeObject(outputValue);
+
+  if (typeof coercedValue === 'boolean') {
+    return coercedValue ? 1 : 0;
   }
 
-  let num = outputValue;
-  if (typeof outputValue === 'string' && outputValue !== '') {
-    num = Number(outputValue);
+  let num = coercedValue;
+  if (typeof coercedValue === 'string' && coercedValue !== '') {
+    num = Number(coercedValue);
   }
+
   if (!isFinite(num)) {
     throw new GraphQLError(
-      `Float cannot represent non numeric value: ${inspect(outputValue)}`,
+      `Float cannot represent non numeric value: ${inspect(coercedValue)}`,
     );
   }
   return num;
@@ -191,14 +196,16 @@ export const GraphQLString = new GraphQLScalarType({
 });
 
 function serializeBoolean(outputValue: mixed): boolean {
-  if (typeof outputValue === 'boolean') {
-    return outputValue;
+  const coercedValue = serializeObject(outputValue);
+
+  if (typeof coercedValue === 'boolean') {
+    return coercedValue;
   }
-  if (isFinite(outputValue)) {
-    return outputValue !== 0;
+  if (isFinite(coercedValue)) {
+    return coercedValue !== 0;
   }
   throw new GraphQLError(
-    `Boolean cannot represent a non boolean value: ${inspect(outputValue)}`,
+    `Boolean cannot represent a non boolean value: ${inspect(coercedValue)}`,
   );
 }