如何使用Go的mongo驱动程序在Mongodb查询上创建视图？

Question

I am working with Golang and Mongodb. I am using https://godoc.org/gopkg.in/mgo.v2 mongo driver for Go. I want to write views on my queries but I found that there is no function defined for that. Mongo Views is a recent feature provided in version 3.4. I have checked it in other driver also:

https://godoc.org/github.com/mongodb/mongo-go-driver/mongo

Its not even there. How can I get this feature in my driver ?

Answer 1

I want to write views on my queries but I found that there is no function defined for that.

Since MongoDB v3.4, there's a support for creating read-only views from existing collections or other views.

In order to create a view, you can execute create() database command. For example:

db.runCommand( { create: <view>, 
                 viewOn: <source>, 
                 pipeline: <pipeline>, 
                 collation: <collation> 
} );

For example if you have a create view command from mongo shell as below:

db.runCommand( {create:"testview", 
                viewOn: "collectionName", 
                pipeline: [ {"$project":{ "fieldA":1 } } ] 
});

Utilising mongo-go-driver (currently version 0.0.9), the above create view command can be written in Go as below:

_, err = database.RunCommand(
    context.Background(),
    bson.NewDocument(bson.EC.String("create", "testview"),
                     bson.EC.String("viewOn", "collectionName"),
                     bson.EC.ArrayFromElements(
                         "pipeline", bson.VC.DocumentFromElements(
                             bson.EC.SubDocumentFromElements(
                                 "$project", bson.EC.Int32("fieldA", 1),),
                             ),
                         ),
                     ),
)