基础用法

collection := client.Database("baz").Collection("qux")
res, err := collection.InsertOne(context.Background(), bson.M{"hello": "world"})
if err != nil { return err }
id := res.InsertedID

源码

func (coll *Collection) InsertOne(ctx context.Context, document interface{},
	opts ...*options.InsertOneOptions) (*InsertOneResult, error) {

	ioOpts := options.MergeInsertOneOptions(opts...)
	imOpts := options.InsertMany()                          // InsertMany creates a new InsertManyOptions instance.

	if ioOpts.BypassDocumentValidation != nil && *ioOpts.BypassDocumentValidation {
		imOpts.SetBypassDocumentValidation(*ioOpts.BypassDocumentValidation)
	}
	res, err := coll.insert(ctx, []interface{}{document}, imOpts)

	rr, err := processWriteError(err)
	if rr&rrOne == 0 {
		return nil, err
	}
	return &InsertOneResult{InsertedID: res[0]}, err
}

func (coll *Collection) insert(ctx context.Context, documents []interface{},
	opts ...*options.InsertManyOptions) ([]interface{}, error) {

	if ctx == nil {
		ctx = context.Background()
	}

	result := make([]interface{}, len(documents))
	docs := make([]bsoncore.Document, len(documents)) // Document is a raw bytes representation of a BSON document.

	for i, doc := range documents {
		var err error
        // transformAndEnsureID is a hack that makes it easy to get a RawValue as the _id value.
        // It will also add an ObjectID _id as the first key if it not already present in the passed-in val.
		docs[i], result[i], err = transformAndEnsureID(coll.registry, doc) 
		if err != nil {
			return nil, err
		}
	}

	sess := sessionFromContext(ctx)
	if sess == nil && coll.client.sessionPool != nil {
		var err error
		sess, err = session.NewClientSession(coll.client.sessionPool, coll.client.id, session.Implicit)
		if err != nil {
			return nil, err
		}
		defer sess.EndSession()
	}

	err := coll.client.validSession(sess)
	if err != nil {
		return nil, err
	}

	wc := coll.writeConcern
	if sess.TransactionRunning() {
		wc = nil
	}
	if !writeconcern.AckWrite(wc) {
		sess = nil
	}

	selector := makePinnedSelector(sess, coll.writeSelector)

	op := operation.NewInsert(docs...).
		Session(sess).WriteConcern(wc).CommandMonitor(coll.client.monitor).
		ServerSelector(selector).ClusterClock(coll.client.clock).
		Database(coll.db.name).Collection(coll.name).
		Deployment(coll.client.deployment).Crypt(coll.client.cryptFLE).Ordered(true).
		ServerAPI(coll.client.serverAPI)
	imo := options.MergeInsertManyOptions(opts...)
	if imo.BypassDocumentValidation != nil && *imo.BypassDocumentValidation {
		op = op.BypassDocumentValidation(*imo.BypassDocumentValidation)
	}
	if imo.Ordered != nil {
		op = op.Ordered(*imo.Ordered)
	}
	retry := driver.RetryNone
	if coll.client.retryWrites {
		retry = driver.RetryOncePerCommand
	}
	op = op.Retry(retry)

	err = op.Execute(ctx)
	wce, ok := err.(driver.WriteCommandError)
	if !ok {
		return result, err
	}

	// remove the ids that had writeErrors from result
	for i, we := range wce.WriteErrors {
		// i indexes have been removed before the current error, so the index is we.Index-i
		idIndex := int(we.Index) - i
		// if the insert is ordered, nothing after the error was inserted
		if imo.Ordered == nil || *imo.Ordered {
			result = result[:idIndex]
			break
		}
		result = append(result[:idIndex], result[idIndex+1:]...)
	}

	return result, err
}

func transformAndEnsureID(registry *bsoncodec.Registry, val interface{}) (bsoncore.Document, interface{}, error) {
	if registry == nil {
		registry = bson.NewRegistryBuilder().Build()
	}
	switch tt := val.(type) {
	case nil:
		return nil, nil, ErrNilDocument
	case bsonx.Doc:
		val = tt.Copy()
	case []byte:
		// Slight optimization so we'll just use MarshalBSON and not go through the codec machinery.
		val = bson.Raw(tt)
	}

	// TODO(skriptble): Use a pool of these instead.
	doc := make(bsoncore.Document, 0, 256)
	doc, err := bson.MarshalAppendWithRegistry(registry, doc, val)
	if err != nil {
		return nil, nil, MarshalError{Value: val, Err: err}
	}

	var id interface{}

	value := doc.Lookup("_id")
	switch value.Type {
	case bsontype.Type(0):
		value = bsoncore.Value{Type: bsontype.ObjectID, Data: bsoncore.AppendObjectID(nil, primitive.NewObjectID())}
		olddoc := doc
		doc = make(bsoncore.Document, 0, len(olddoc)+17) // type byte + _id + null byte + object ID
		_, doc = bsoncore.ReserveLength(doc)
		doc = bsoncore.AppendValueElement(doc, "_id", value)
		doc = append(doc, olddoc[4:]...) // remove the length
		doc = bsoncore.UpdateLength(doc, 0, int32(len(doc)))
	default:
		// We copy the bytes here to ensure that any bytes returned to the user aren't modified
		// later.
		buf := make([]byte, len(value.Data))
		copy(buf, value.Data)
		value.Data = buf
	}

	err = bson.RawValue{Type: value.Type, Value: value.Data}.UnmarshalWithRegistry(registry, &id)
	if err != nil {
		return nil, nil, err
	}

	return doc, id, nil
}