[Go] optional boolean properties set to false are omitted when encoded

[drennalls]

Description

If an object defines an optional boolean property it does not end up in the JSON if the value is false

Swagger-codegen version

2.2.2

Swagger declaration file content or url

swagger: '2.0'
info:
  description: 'Demonstrate golang codegen bug'
  version: 1.0.0
schemes:
  - http
paths:
  /pet:
    post:
      summary: Add a new pet to the store
      description: ''
      operationId: addPet
      consumes:
        - application/json
      produces:
        - application/json
      parameters:
        - in: body
          name: body
          description: Pet object that needs to be added to the store
          required: true
          schema:
            $ref: '#/definitions/Pet'
      responses:
        '405':
          description: Invalid input
definitions:
  Pet:
    title: a Pet
    description: A pet for sale in the pet store
    type: object
    required:
      - name
    properties:
      id:
        type: integer
        format: int64
      name:
        type: string
        example: doggie
      vaccinated:
        type: boolean
        description: Indicates whether the Pet's vaccinations are up-to-date

Command line used for generation

java -jar target/swagger-codegen-cli.jar generate -i ./mypetstore.yaml -l go -o ./mypetstore-client-go

Steps to reproduce

Include an optional boolean property (like vaccinated in the API above), set to false and encode it. The field will be missing from the JSON.

Related issues/PRs

If the property is marked as required then things work as expected which I guess was a result of #4665

Suggest a fix/enhancement

Don't use omitempty for boolean properties, even if optional...
from https://golang.org/pkg/encoding/json/

The "omitempty" option specifies that the field should be omitted from the encoding if the field has an empty value, defined as false, 0, a nil pointer, a nil interface value, and any empty array, slice, map, or string.

..if you do then sending a false for optional properties is not possible.

[wing328]

@drennalls Can you please try the latest stable version (2.3.0), which has the Go API client refactored?

[luism6n]

This happens in version 2.4.0-SNAPSHOT. Reproduced as follows:

Got petstore.yaml

And add:

...
      vaccinated:
        type: boolean
        description: indicate if pet is vaccinated
...

To the Pet object definition.

Generate the client:

$ ./run-in-docker.sh generate -i issue7391.yaml -l go -o /gen/out/issue7391 -DpackageName=issue7391
$ ln -s ${PWD}/out $(go env GOPATH)/src/out

Create a dummy server:

from flask import Flask, request

app = Flask(__name__)

@app.route('/pet', methods=['POST'])
def root():
    content = request.json
    print content
    return "all right"

app.run(port=8080)

Run a Go test:

package main

import (
	"fmt"
	"out/issue7391"
	"testing"
)

func TestPost(t *testing.T) {
	config := issue7391.NewConfiguration()
	config.BasePath = "http://localhost:8080"
	client := issue7391.NewAPIClient(config)

	pet := issue7391.Pet{
		Name: "john",
		// Vaccinated: false,
	}

	res, err := client.PetApi.AddPet(nil, pet)
	fmt.Printf("%+v\n%+v\n", res, err)
}

Running with or without commenting on that line, the server logs:

{u'name': u'john', u'photoUrls': None}
127.0.0.1 - - [31/Jan/2018 11:59:48] "POST /pet HTTP/1.1" 200 -

Manually changing the model_pet.go generated from:

...
	Vaccinated bool `json:"vaccinated,omitempty"`
...

to

...
	Vaccinated bool `json:"vaccinated"`
...

Again, running with or without commenting the Vaccinated: false line, the server logs:

127.0.0.1 - - [31/Jan/2018 11:59:58] "POST /pet HTTP/1.1" 200 -
{u'vaccinated': False, u'name': u'john', u'photoUrls': None}

So removing omitempty won't fix the problem, since the property will always be false if empty. Surprisingly, changing the property to:

...
	Vaccinated *bool `json:"vaccinated"`
...

Actualy works as intended. Maybe it's an option?

/cc @drennalls @wing328

[wing328]

I thought removing omitempty would work. Can you also share the Go version you're using?

cc @antihax @bvwells

[luism6n]

Sure:

$ go version
go version go1.9.3 linux/amd64

[tenmozes]

@drennalls hello, setting default value should help

    vaccinated:
        type: boolean
        default:false
        description: indicate if pet is vaccinated

[kevinmu]

I seem to be running into this issue as well. Providing a default as @tenmozes suggested yields

 Vaccinated *bool `json:"vaccinated,omitempty"`

which does work. However, my question is whether we should also consider using this style even when a default is NOT provided?

Personally, I can't think of an instance where the existing

 Vaccinated bool `json:"vaccinated,omitempty"`

would be preferred over the pointer version that is generated when you provide a default. What do y'all think / can you think of one such scenario? In fact, wouldn't we run into this same issue with all scalar types (e.g., int, string)? Under the current scheme there is no way to pass 0 or an empty string unless you specify a default.

[etiennedi]

It seems the fix by setting a default outlined in #7391 (comment) does not work for fields of type number when the default is 0.

No default

The following:

    latitude:
        type: number
        description: the latitude in decimal format

leads to

Latitude float32 `json:"latitude,omitempty"` 

as expected.

Default != 0

Setting a default other than 0 will lead to the expecting pointer construct, such as:

    latitude:
        type: number
        default: 5
        description: the latitude in decimal format

leads to

Latitude *float32 `json:"latitude,omitempty"` 

as expected after knowing this fixes it for bool fields as well.

Default == 0

However, when the default is 0 (which is the default value of a float32, similar to how false is the default value of a bool), we don't end up with the pointer construct:

    latitude:
        type: number
        default: 0
        description: the latitude in decimal format

leads to

Latitude float32 `json:"latitude,omitempty"` 

So, fixing this by setting a default, does not work if the default is 0.

[InTheCloudDan]

I'm testing with version CLI 2.4.8 and it's no longer generating pointers for booleans when setting a default value.