Something like this:
type Author struct {
ID primitive.ObjectID `bson:"_id"`
CreatedAt time.Time `bson:"created_at"`
...
}
type Data struct {
Author []Author `bson:"author"`
}
Then you read the results into var result []Data
On Thu, Nov 16, 2023 at 10:39 AM Tong Sun <[email protected]> wrote:
>
> Thanks for the hint. would you elaborate a bit more please as I'm still
> unsure how to do it. and the closes hits that I found are
>
> https://stackoverflow.com/questions/71739971/unmarshalling-a-bson-d-object-golang
> https://www.mongodb.com/docs/drivers/go/current/fundamentals/bson/
>
>
> But neither covers how to unmarshal bson.M types. I got either:
>
> cannot use r (variable of type interface{}) as []byte value in argument to
> bson.Unmarshal: need type assertion
>
> Or with:
>
> r := val["author"].(primitive.A)[0]
> var a1 author
> bson.Unmarshal(r.([]byte), &a1)
> a = append(a, a1)
>
> I'm getting:
>
> panic: interface conversion: interface {} is primitive.M, not []uint8
>
>
> On Thursday, November 16, 2023 at 12:20:13 PM UTC-5 burak serdar wrote:
>
> val["author"].(primitive.A)[0] is correct, but the type of that
> expression is not author, it is bson.M. You might consider using a
> tagged struct to unmarshal this.
>
> On Thu, Nov 16, 2023 at 10:11 AM Tong Sun wrote:
> >
> > Further on with the question
> > https://stackoverflow.com/questions/60072372/filtering-values-out-of-a-bson-m-in-golang/
> > where the answer says to use `range server.installed` while the comment says
> >
> > server.host undefined (type string has no field or method subject)
> >
> > This is what I've tried with the MongoDB `[]bson.M{}` type results
> > (obtained from like `$lookup`):
> >
> > The []bson.M{} type of result I'm getting is:
> >
> > [map[_id:ObjectID("65529d178688bac31b739f82")
> > author:[map[_id:ObjectID("65529d168688bac31b739f81")
> > created_at:1699912982379 name:Mehran updated_at:1699912982379]]
> > author_id:ObjectID("65529d168688bac31b739f81") created_at:1699912983386
> > name:Test pages:124 updated_at:1699912983386]]
> >
> > I've made several attempts but was unable to access the author field of the
> > lookup result in Go.
> >
> > a := []author{}
> > for _, val := range result { a = append(a, val["author"].(primitive.A)[0]) }
> >
> > If using val.author, I'm getting val.author undefined (type primitive.M has
> > no field or method author)
> > If using val["author"], I'm getting invalid operation: cannot index
> > val["author"] (map index expression of type interface{})
> > If using val["author"].(primitive.A)[0], I'm getting cannot use
> > val["author"].(primitive.A)[0] (variable of type interface{}) as author
> > value in argument to append: need type assertion
> >
> >
> > And how to go about to fix this "need type assertion" just stumbled me, as
> > I've tried val["author"].(primitive.A).([]main.author)[0], or
> > []author(val["author"].(primitive.A))[0], but I'm getting invalid
> > operation: cannot call non-function val["author"].(primitive.A) (comma, ok
> > expression of type primitive.A)
> >
> > and I've now run out of ideas how to fix it.
> > Please help
>
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