How to query association after successful db.Save() - mysql

Question

I am working with Gorm and Graphql. I hadn't run into problems querying data until I tried to connect two existing items using their foreignkey relationships. Here are my two models:
type Report struct {
db.Base
OwnerID string
Patient patients.Patient `gorm:"association_name:Patient;"`
PatientID string
}
type Patient struct {
db.Base
ReportID string
}
I have a function to save the relationship to the database:
func (s *Store) AddPatientToReport(ctx context.Context, id string, patient *patients.Patient) (*Report, error) {
// check against user using context
report, err := s.Report(ctx, id)
if err != nil {
log.Error("Could not find report.")
return nil, err
}
report.PatientID = patient.ID
if err := s.db.Save(&report).Association("Patient").Append(patient).Error; err != nil {
log.WithError(err).Error("add patient failed")
return nil, err
}
return report, nil
}
After the above function I can query the Report and see the patient_id. I can also query the Patient and see the report_id. But the following query to get the whole Patient from the Report just returns empty.
query {
report(id: "report_id") {
id
patientID // this will return the correct patient_id
patient {
id // this field always comes back as an empty string
}
}
}
Here is how the DB is setup:
// NewConn creates a new database connection
func NewConn(cc ConnConf) (*Conn, error) {
db, err := gorm.Open("mysql", cc.getCtxStr())
if err != nil {
return nil, err
}
// Models are loaded from each package. Patients is created before Reports.
if err := db.AutoMigrate(Models...).Error; err != nil {
log.Fatal(err)
}
db.LogMode(cc.Logger)
return &Conn{db}, err
}
I can't figure out how to get the whole patient back. Any suggestions?

Answer 1

Ok, so as it turns out I just needed to ask and then I'd figure it out on my own a few minutes later.
I'd read about Preload() in the Gorm docs, but didn't know where to implement it. I first tried when the DB fired up thinking it would load the associations. But I really needed to use Preload() as I run the query.
result := &Report{}
if err = s.db.Preload("Patient").Where(&query).First(&result).Error; err != nil {
log.WithField("id", id).WithError(err).
Error("could not find report")
return nil, err
}
Now, the graphql query:
query {
report(id: "some_id") {
id
patient {
id // now it returns the id
birthyear // now it returns other fields, too
...
}
}
}