GraphQL\Executor\Values::coerceValue PHP Method

    private static function coerceValue(Type $type, $value)
    {
        $undefined = Utils::undefined();
        if ($value === $undefined) {
            return $undefined;
        }
        if ($type instanceof NonNull) {
            if ($value === null) {
                // Intentionally return no value.
                return $undefined;
            }
            return self::coerceValue($type->getWrappedType(), $value);
        }
        if (null === $value) {
            return null;
        }
        if ($type instanceof ListOfType) {
            $itemType = $type->getWrappedType();
            if (is_array($value) || $value instanceof \Traversable) {
                $coercedValues = [];
                foreach ($value as $item) {
                    $itemValue = self::coerceValue($itemType, $item);
                    if ($undefined === $itemValue) {
                        // Intentionally return no value.
                        return $undefined;
                    }
                    $coercedValues[] = $itemValue;
                }
                return $coercedValues;
            } else {
                $coercedValue = self::coerceValue($itemType, $value);
                if ($coercedValue === $undefined) {
                    // Intentionally return no value.
                    return $undefined;
                }
                return [$coercedValue];
            }
        }
        if ($type instanceof InputObjectType) {
            $coercedObj = [];
            $fields = $type->getFields();
            foreach ($fields as $fieldName => $field) {
                if (!array_key_exists($fieldName, $value)) {
                    if ($field->defaultValueExists()) {
                        $coercedObj[$fieldName] = $field->defaultValue;
                    } else {
                        if ($field->getType() instanceof NonNull) {
                            // Intentionally return no value.
                            return $undefined;
                        }
                    }
                    continue;
                }
                $fieldValue = self::coerceValue($field->getType(), $value[$fieldName]);
                if ($fieldValue === $undefined) {
                    // Intentionally return no value.
                    return $undefined;
                }
                $coercedObj[$fieldName] = $fieldValue;
            }
            return $coercedObj;
        }
        if ($type instanceof LeafType) {
            $parsed = $type->parseValue($value);
            if (null === $parsed) {
                // null or invalid values represent a failure to parse correctly,
                // in which case no value is returned.
                return $undefined;
            }
            return $parsed;
        }
        throw new InvariantViolation('Must be input type');
    }

 /**
  * Given a type and any value, return a runtime value coerced to match the type.
  */
 private static function coerceValue(Type $type, $value)
 {
     if ($type instanceof NonNull) {
         // Note: we're not checking that the result of coerceValue is non-null.
         // We only call this function after calling isValidValue.
         return self::coerceValue($type->getWrappedType(), $value);
     }
     if (null === $value) {
         return null;
     }
     if ($type instanceof ListOfType) {
         $itemType = $type->getWrappedType();
         // TODO: support iterable input
         if (is_array($value)) {
             return array_map(function ($item) use($itemType) {
                 return Values::coerceValue($itemType, $item);
             }, $value);
         } else {
             return [self::coerceValue($itemType, $value)];
         }
     }
     if ($type instanceof InputObjectType) {
         $fields = $type->getFields();
         $obj = [];
         foreach ($fields as $fieldName => $field) {
             $fieldValue = self::coerceValue($field->getType(), isset($value[$fieldName]) ? $value[$fieldName] : null);
             if (null === $fieldValue) {
                 $fieldValue = $field->defaultValue;
             }
             if (null !== $fieldValue) {
                 $obj[$fieldName] = $fieldValue;
             }
         }
         return $obj;
     }
     Utils::invariant($type instanceof ScalarType || $type instanceof EnumType, 'Must be input type');
     return $type->parseValue($value);
 }