block6.go

func (cc *CPaperImpl) List(ctx router.Context, in *empty.Empty) (*schema.CommercialPaperList, error) {
	if res, err := cc.state(ctx).List(&schema.CommercialPaper{}); err != nil {
		return nil, err
	} else {
		return res.(*schema.CommercialPaperList), nil
	}
}

func (cc *CPaperImpl) Get(ctx router.Context, id *schema.CommercialPaperId) (*schema.CommercialPaper, error) {
	if res, err := cc.state(ctx).Get(id, &schema.CommercialPaper{}); err != nil {
		return nil, err
	} else {
		return res.(*schema.CommercialPaper), nil
	}
}

func (cc *CPaperImpl) Issue(ctx router.Context, issue *schema.IssueCommercialPaper) (*schema.CommercialPaper, error) {
	// Validate input message using the rules defined in schema
	if err := issue.Validate(); err != nil {
		return nil, errors.Wrap(err, "payload validation")
	}

	// Create state entry
	cpaper := &schema.CommercialPaper{
		Issuer:       issue.Issuer,
		PaperNumber:  issue.PaperNumber,
		Owner:        issue.Issuer,
		IssueDate:    issue.IssueDate,
		MaturityDate: issue.MaturityDate,
		FaceValue:    issue.FaceValue,
		State:        schema.CommercialPaper_ISSUED, // Initial state
		ExternalId:   issue.ExternalId,
	}

	if err := cc.event(ctx).Set(issue); err != nil {
		return nil, err
	}

	if err := cc.state(ctx).Insert(cpaper); err != nil {
		return nil, err
	}
	return cpaper, nil
}

...