[PHP] Bug json_encode is casting floats to integers due to missing 'JSON_PRESERVE_ZERO_FRACTION' flag

[PHP] Bug json_encode is casting floats to integers due to missing 'JSON_PRESERVE_ZERO_FRACTION' flag in json_encode __toString methods

Description

When json_encode is called on object which one property is float, it will cast it to integer due to the missing 'JSON_PRESERVE_ZERO_FRACTION' on the json_encode. This leads to denormalization/validation problems when float is expected and integer is received. 'JSON_PRESERVE_ZERO_FRACTION' flag should be added by default to json_encode

Swagger-codegen version

swaggerapi/swagger-codegen-cli-v3:3.0.11

Suggest a fix/enhancement

Since I had multiple problems with my local java and mvn instances I don't know for sure, but I think the file that needs changing is the following:

modules/swagger-codegen/src/main/resources/php/model_generic.mustache

From this:

public function __toString()
    {
        if (defined('JSON_PRETTY_PRINT')) { // use JSON pretty print
            return json_encode(
                ObjectSerializer::sanitizeForSerialization($this),
                JSON_PRETTY_PRINT
            );
        }

        return json_encode(ObjectSerializer::sanitizeForSerialization($this));
    }

To something like this:

public function __toString()
    {
        if (defined('JSON_PRESERVE_ZERO_FRACTION') && defined('JSON_PRETTY_PRINT')) { // use JSON preserve zero fraction && JSON pretty print
            return json_encode(
                ObjectSerializer::sanitizeForSerialization($this),
                JSON_PRESERVE_ZERO_FRACTION|JSON_PRETTY_PRINT
            );
        }

        if (defined('JSON_PRETTY_PRINT')) { // use JSON pretty print
            return json_encode(
                ObjectSerializer::sanitizeForSerialization($this),
                JSON_PRETTY_PRINT
            );
        }

        return json_encode(ObjectSerializer::sanitizeForSerialization($this));
    }

Start with modules/swagger-codegen/src/main/resources/php/model_generic.mustache and inspect the generated PHP model __toString method and its current json_encode flags. Update the template so supported serialization preserves zero-fraction floats while retaining pretty-print behavior; done means generated models no longer turn values such as 1.0 into 1.