How to Store Datetime Values in Dynamodb - amazon-web-services

Question

Given the following functions to create and then retrieve an item...
type Auth struct {
UserID string `dynamodbav:"UserId"`
ExpiresOn time.Time `dynamodbav:"ExpiresOn,unixtime"`
}
func (r *AuthRepository) Create(auth *Auth) (*Auth, error) {
deviceCode, err := c.NewDeviceCode()
if err != nil {
return nil, err
}
item, err := attributevalue.MarshalMap(auth)
if err != nil {
return nil, err
}
input := &dynamodb.PutItemInput{
Item: item,
TableName: aws.String("MyTable"),
}
_, err = r.svc.PutItem(r.ctx, input)
return auth, nil
}
func (r *AuthRepository) Get(userID string) (*Auth, error) {
input := &dynamodb.GetItemInput{
TableName: aws.String("MyTable"),
Key: map[string]types.AttributeValue{
"UserId": &types.AttributeValueMemberS{*aws.String(userID)},
},
}
result, err := r.svc.GetItem(r.ctx, input)
if err != nil {
return nil, err
}
var auth *Auth = nil
if len(result.Item) > 0 {
auth = &Auth{}
if err := attributevalue.UnmarshalMap(result.Item, &auth); err != nil {
return nil, err
}
}
return auth, nil
}
... I create a new item with that should expire in 30 minutes like this:
repo.Create(&auth.Auth{
UserID: "XYZ",
ExpiresOn: time.Now().Add(time.Duration(1800) * time.Second), // expires in 30 mins
})
Then, I retrieve the item created above and I check whether it has expired:
authEntry, err := repo.GetByUserCode("XYZ")
if authEntry.ExpiresOn.Before(time.Now()) {
// I always get here as Before evaluates to true
}
As I noted in the code snippet above, if I create an entry with an expiry time of now + 30 minutes, and then I immediately retrieve that record to check if ExpiresOn is before now, I always get true...
What's the correct way to store datetime in DynamoDB?