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MongoDB Golang Driver Ensure Index
package mgoutil
import (
"context"
"github.com/mongodb/mongo-go-driver/bson"
"github.com/mongodb/mongo-go-driver/mongo"
"github.com/pkg/errors"
)
// EnsureIndex will ensure the index model provided is on the given collection.
func EnsureIndex(ctx context.Context, c *mongo.Collection, keys []string, opts *mongo.IndexOptionsBuilder) error {
idxs := c.Indexes()
ks := bson.NewDocument()
for _, k := range keys {
// todo - add support for sorting index.
ks.Append(bson.EC.Int64(k, -1))
}
idm := mongo.IndexModel{
Keys: ks,
Options: opts.Build(),
}
v := idm.Options.Lookup("name")
if v == nil {
return errors.New("must provide a key name for index")
}
expectedName := v.StringValue()
cur, err := idxs.List(ctx)
if err != nil {
return errors.Wrap(err, "unable to list indexes")
}
found := false
for cur.Next(ctx) {
d := bson.NewDocument()
if err := cur.Decode(d); err != nil {
return errors.Wrap(err, "unable to decode bson index document")
}
v := d.Lookup("name")
if v != nil && v.StringValue() == expectedName {
found = true
break
}
}
if found {
return nil
}
_, err = idxs.CreateOne(ctx, idm)
return err
}
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