Make coercion code more explicit.

Author: IvanGoncharov

src/type/__tests__/serialization-test.js

@@ -69,7 +69,7 @@ describe('Type System: Scalar coercion', () => {
       'Int cannot represent non-integer value: Infinity',
     );
     expect(() => GraphQLInt.serialize([5])).to.throw(
-      'Int cannot represent an array value: [5]',
+      'Int cannot represent non-integer value: [5]',
     );
   });
 
@@ -98,7 +98,7 @@ describe('Type System: Scalar coercion', () => {
       'Float cannot represent non numeric value: ""',
     );
     expect(() => GraphQLFloat.serialize([5])).to.throw(
-      'Float cannot represent an array value: [5]',
+      'Float cannot represent non numeric value: [5]',
     );
   });
 

src/type/scalars.js

@@ -22,13 +22,14 @@ const MAX_INT = 2147483647;
 const MIN_INT = -2147483648;
 
 function serializeInt(value: mixed): number {
-  if (Array.isArray(value)) {
-    throw new TypeError(
-      `Int cannot represent an array value: ${inspect(value)}`,
-    );
+  let num = value;
+  if (typeof value === 'string' && value !== '') {
+    num = Number(value);
+  } else if (typeof value === 'boolean') {
+    return value ? 1 : 0;
   }
-  const num = Number(value);
-  if (value === '' || !isInteger(num)) {
+
+  if (!isInteger(num)) {
     throw new TypeError(
       `Int cannot represent non-integer value: ${inspect(value)}`,
     );
@@ -74,13 +75,14 @@ export const GraphQLInt = new GraphQLScalarType({
 });
 
 function serializeFloat(value: mixed): number {
-  if (Array.isArray(value)) {
-    throw new TypeError(
-      `Float cannot represent an array value: ${inspect(value)}`,
-    );
+  let num = value;
+  if (typeof value === 'string' && value !== '') {
+    num = Number(value);
+  } else if (typeof value === 'boolean') {
+    return value ? 1 : 0;
   }
-  const num = Number(value);
-  if (value === '' || !isFinite(num)) {
+
+  if (!isFinite(num)) {
     throw new TypeError(
       `Float cannot represent non numeric value: ${inspect(value)}`,
     );
@@ -120,14 +122,16 @@ function serializeString(value: mixed): string {
     value && typeof value.valueOf === 'function' ? value.valueOf() : value;
   // Serialize string, boolean and number values to a string, but do not
   // attempt to coerce object, function, symbol, or other types as strings.
-  if (
-    typeof result !== 'string' &&
-    typeof result !== 'boolean' &&
-    !isFinite(result)
-  ) {
-    throw new TypeError(`String cannot represent value: ${inspect(result)}`);
-  }
-  return String(result);
+  if (typeof result === 'string') {
+    return result;
+  }
+  if (typeof result === 'boolean') {
+    return result ? 'true' : 'false';
+  }
+  if (isFinite(result)) {
+    return result.toString();
+  }
+  throw new TypeError(`String cannot represent value: ${inspect(value)}`);
 }
 
 function coerceString(value: mixed): string {
@@ -153,12 +157,15 @@ export const GraphQLString = new GraphQLScalarType({
 });
 
 function serializeBoolean(value: mixed): boolean {
-  if (typeof value !== 'boolean' && !isFinite(value)) {
-    throw new TypeError(
-      `Boolean cannot represent a non boolean value: ${inspect(value)}`,
-    );
+  if (typeof value === 'boolean') {
+    return value;
   }
-  return Boolean(value);
+  if (isFinite(value)) {
+    return value !== 0;
+  }
+  throw new TypeError(
+    `Boolean cannot represent a non boolean value: ${inspect(value)}`,
+  );
 }
 
 function coerceBoolean(value: mixed): boolean {
@@ -185,17 +192,23 @@ function serializeID(value: mixed): string {
   // to represent an object identifier (ex. MongoDB).
   const result =
     value && typeof value.valueOf === 'function' ? value.valueOf() : value;
-  if (typeof result !== 'string' && !isInteger(result)) {
-    throw new TypeError(`ID cannot represent value: ${inspect(value)}`);
+  if (typeof result === 'string') {
+    return result;
   }
-  return String(result);
+  if (isInteger(result)) {
+    return String(result);
+  }
+  throw new TypeError(`ID cannot represent value: ${inspect(value)}`);
 }
 
 function coerceID(value: mixed): string {
-  if (typeof value !== 'string' && !isInteger(value)) {
-    throw new TypeError(`ID cannot represent value: ${inspect(value)}`);
+  if (typeof value === 'string') {
+    return value;
+  }
+  if (isInteger(value)) {
+    return value.toString();
   }
-  return String(value);
+  throw new TypeError(`ID cannot represent value: ${inspect(value)}`);
 }
 
 export const GraphQLID = new GraphQLScalarType({