Add MultiAssetModeService for Future

[jeonghoyeo7]

I found the endpoint /fapi/v1/multiAssetsMargin is not supported yet to get or change the multi-asset mode of a user.
I added the related services accordingly in the following files in v2/futures.

• client.go
• position_service.go
• position_service_test.go

[jeonghoyeo7]

Hello @adshao .
Could you take a time to review this PR?
Thank you!

[adshao]

Suggested change

	multiAssetsMargin string
	multiAssetsMargin bool

[jeonghoyeo7]

I referred https://binance-docs.github.io/apidocs/futures/en/#change-multi-assets-mode-trade, where it is seen as
POST /fapi/v1/multiAssetsMargin (HMAC SHA256) has the parameter as below.
multiAssetsMargin | STRING | YES | "true": Multi-Assets Mode; "false": Single-Asset Mode

I follow the Binance api doc. When getting multi-asset mode, the response is bool type, but when we change by POST, its parameter multi-asset mode is string type.

[adshao]

Suggested change

	if multiAssetsMargin {
	s.multiAssetsMargin = "true"
	} else {
	s.multiAssetsMargin = "false"
	}
	s.multiAssetsMargin = multiAssetsMargin

[jeonghoyeo7]

Same comment as above.

[adshao]

Hello @adshao . Could you take a time to review this PR? Thank you!

Thank you for the work, please check my review comments.

[jeonghoyeo7]

Thank you for your review and comments.

In summary, from https://binance-docs.github.io/apidocs/futures/en/#change-multi-assets-mode-trade, where it is seen as
POST /fapi/v1/multiAssetsMargin (HMAC SHA256) has the parameter as below.
multiAssetsMargin | STRING | YES | "true": Multi-Assets Mode; "false": Single-Asset Mode

Following the above link, it seems multiAssetsMargin, which will become s.multiAssetsMargin, should be a string.

[adshao]

Thank you for your review and comments.

In summary, from https://binance-docs.github.io/apidocs/futures/en/#change-multi-assets-mode-trade, where it is seen as POST /fapi/v1/multiAssetsMargin (HMAC SHA256) has the parameter as below. multiAssetsMargin | STRING | YES | "true": Multi-Assets Mode; "false": Single-Asset Mode

Following the above link, it seems multiAssetsMargin, which will become s.multiAssetsMargin, should be a string.

setFormParams will automatically convert bool to string before submitting the form.

[jeonghoyeo7]

Thanks for further explanation.

As I reviewed ChangePositionModeService and DualSide function, ChangePositionModeService has the same case as MultiAssetModeService in that they have the same type parameter of string.

Is setFormParams applied only to MultiAssetModeService or both cases? Then, does the following code need to be modified from

func (s *ChangePositionModeService) DualSide(dualSide bool) *ChangePositionModeService {
	if dualSide {
		s.dualSide = "true"
	} else {
		s.dualSide = "false"
	}
	return s
}

to

func (s *ChangePositionModeService) DualSide(dualSide bool) *ChangePositionModeService {
	s.dualSide = dualSide
	return s
}

? But, after reviewing

r.setFormParams(params{
		"dualSidePosition": s.dualSide,
	})
```,
the existing part related to ChangePositionModeService looks correct.

It seems because of the following part,

r.setFormParams(params{
"multiAssetsMargin": s.multiAssetsMargin,
})

`s.multiAssetsMargin` seems to be required to be string.

[adshao]

Thanks for further explanation.

As I reviewed ChangePositionModeService and DualSide function, ChangePositionModeService has the same case as MultiAssetModeService in that they have the same type parameter of string.

Is setFormParams applied only to MultiAssetModeService or both cases? Then, does the following code need to be modified from

func (s *ChangePositionModeService) DualSide(dualSide bool) *ChangePositionModeService {
	if dualSide {
		s.dualSide = "true"
	} else {
		s.dualSide = "false"
	}
	return s
}

to

func (s *ChangePositionModeService) DualSide(dualSide bool) *ChangePositionModeService {
	s.dualSide = dualSide
	return s
}

? But, after reviewing

r.setFormParams(params{
		"dualSidePosition": s.dualSide,
	})
```,
the existing part related to ChangePositionModeService looks correct.

It seems because of the following part,

r.setFormParams(params{ "multiAssetsMargin": s.multiAssetsMargin, })

`s.multiAssetsMargin` seems to be required to be string.

I think DualSide was added before setFormParams supporting bool directly. You can just verify it in your unit tests.

[jeonghoyeo7]

@adshao Thanks a lot for your comment.
I revised the multiAssetMode related as your suggestion.
And also, I further changed ChangePositionModeService for DualSide similarly.

type ChangePositionModeService struct {
	c        *Client
	dualSide bool
}

// Change user's position mode: true - Hedge Mode, false - One-way Mode
func (s *ChangePositionModeService) DualSide(dualSide bool) *ChangePositionModeService {
	s.dualSide = dualSide
	return s
}

I found setFormParams is also applied to this by

r.setFormParams(params{
	"dualSidePosition": s.dualSide,
})

I checked the related unit tests are all passed.