Select column from Mongodb in golang using mgo

Question

As I know, we can use

> db['twitter-3'].find({}, {"text": 1})

to select all texts in collection.

How can we use mgo to find specific field in golang? I tried

var result []string
err = conn.Find(bson.M{}, bson.M{"text", 1}).All(&result)

But it is not correct.

score 26 · Accepted Answer · answered Jun 29 '15 at 13:25

26

Use the query Select method to specify the fields to return:

var result []struct{ Text string `bson:"text"` }
err := c.Find(nil).Select(bson.M{"text": 1}).All(&result)
if err != nil {
    // handle error
}
for _, v := range result {
     fmt.Println(v.Text)
}

In this example, I declared an anonymous type with the one selected field. It's OK to use a type with all document fields.

answered Jun 29 '15 at 13:25

Charlie Tumahai

113,709
12
249
242

In the structure, what does `bson:"text"` stand for? Is there any reference that I can check to have a better understand for this? – Wyatt Jun 29 '15 at 21:57
1

See the [bson package](http://godoc.org/labix.org/v2/mgo/bson#Marshal) documentation for information on how the package uses field tags. – Charlie Tumahai Jun 29 '15 at 22:00
1

Thanks! How does one select multiple columns? Just adding Select(bson.M{"text": 1, "anotherColumn":1}) does not work. – Amol Nov 29 '17 at 05:03
why `it returns in`type map[][] ` not as json – muthukumar selvaraj Apr 08 '18 at 17:59

score 2 · Answer 2 · answered Feb 23 '18 at 17:16

to select multiple fields:

var result []struct{
    Text string `bson:"text"`
    Otherfield string `bson:"otherfield"`
}

err := c.Find(nil).Select(bson.M{"text": 1, "otherfield": 1}).All(&result)
if err != nil {
   // handle error
}
for _, v := range result {
    fmt.Println(v.Text)
}

score 0 · Answer 3 · answered May 20 '19 at 02:23

0

var result interface{}
err = c.Find(nil).Select(bson.M{"text": 1}).All(&result)

answered May 20 '19 at 02:23

Jyotsna Gupta

21
2

Select column from Mongodb in golang using mgo

3 Answers3