Golang Collection.Find方法代碼示例

// deleteOldPlaceholderCharmsOps returns the txn ops required to delete all placeholder charm
// records older than the specified charm URL.
func deleteOldPlaceholderCharmsOps(st *State, charms mongo.Collection, curl *charm.URL) ([]txn.Op, error) {
	// Get a regex with the charm URL and no revision.
	noRevURL := curl.WithRevision(-1)
	curlRegex := "^" + regexp.QuoteMeta(st.docID(noRevURL.String()))

	var docs []charmDoc
	query := bson.D{{"_id", bson.D{{"$regex", curlRegex}}}, {"placeholder", true}}
	err := charms.Find(query).Select(bson.D{{"_id", 1}, {"url", 1}}).All(&docs)
	if err != nil {
		return nil, errors.Trace(err)
	}
	var ops []txn.Op
	for _, doc := range docs {
		if doc.URL.Revision >= curl.Revision {
			continue
		}
		ops = append(ops, txn.Op{
			C:      charmsC,
			Id:     doc.DocID,
			Assert: stillPlaceholder,
			Remove: true,
		})
	}
	return ops, nil
}

// getEntitiesWithStatuses returns the ids for all entities that
// have history entries
func getEntitiesWithStatuses(coll mongo.Collection) ([]string, error) {
	var globalKeys []string
	err := coll.Find(nil).Distinct("globalkey", &globalKeys)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return globalKeys, nil
}

// getEntitiesWithStatuses returns the ids for all entities that
// have history entries
func getEntitiesWithStatuses(coll mongo.Collection) ([]string, error) {
	var entityKeys []string
	err := coll.Find(nil).Distinct("entityid", &entityKeys)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return entityKeys, nil
}

// getOldestTimeToKeep returns the create time for the oldest
// status log to be kept.
func getOldestTimeToKeep(coll mongo.Collection, globalKey string, size int) (int64, bool, error) {
	result := historicalStatusDoc{}
	err := coll.Find(bson.D{{"globalkey", globalKey}}).Sort("-updated").Skip(size - 1).One(&result)
	if err == mgo.ErrNotFound {
		return -1, false, nil
	}
	if err != nil {
		return -1, false, errors.Trace(err)
	}
	return result.Updated, true, nil

}

// readEntries reads all lease data for the client's namespace.
func (client *client) readEntries(collection mongo.Collection) (map[string]entry, error) {

	// Read all lease documents in the client's namespace.
	query := bson.M{
		fieldType:      typeLease,
		fieldNamespace: client.config.Namespace,
	}
	iter := collection.Find(query).Iter()

	// Extract valid entries for each one.
	entries := make(map[string]entry)
	var leaseDoc leaseDoc
	for iter.Next(&leaseDoc) {
		name, entry, err := leaseDoc.entry()
		if err != nil {
			return nil, errors.Annotatef(err, "corrupt lease document %q", leaseDoc.Id)
		}
		entries[name] = entry
	}
	if err := iter.Close(); err != nil {
		return nil, errors.Trace(err)
	}
	return entries, nil
}

func isNotDeadWithSession(coll mongo.Collection, id interface{}) (bool, error) {
	n, err := coll.Find(bson.D{{"_id", id}, {"life", bson.D{{"$ne", Dead}}}}).Count()
	return n == 1, err
}

func isAliveWithSession(coll mongo.Collection, id interface{}) (bool, error) {
	n, err := coll.Find(bson.D{{"_id", id}, {"life", Alive}}).Count()
	return n == 1, err
}