You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: dbstructs.go
    path of file: ./repos/aether-app/aether-core/aether/io/persistence
    
    the code of the file until where you have to start completion: // Persistence > Structs
// This file contains the struct definitions of the database objects.

package persistence

import (
	"aether-core/aether/io/api"
	// "aether-core/aether/services/compress"
	"aether-core/aether/services/fingerprinting"
	"aether-core/aether/services/logging"
	"encoding/csv"
	"encoding/json"
	"errors"
	"fmt"
	// "github.com/jmoiron/sqlx/types"
	"strings"
	"time"
)

// Basic properties

type DbUpdateable struct {
	LastUpdate        api.Timestamp   `db:"LastUpdate"`
	UpdateProofOfWork api.ProofOfWork `db:"UpdateProofOfWork"`
	UpdateSignature   api.Signature   `db:"UpdateSignature"`
}

type DbProvable struct {
	Creation    api.Timestamp   `db:"Creation"`
	ProofOfWork api.ProofOfWork `db:"ProofOfWork"`
	Signature   api.Signature   `db:"Signature"`
}

// Subentities

type DbBoardOwner struct {
	BoardFingerprint      api.Fingerprint `db:"BoardFingerprint"`
	KeyFingerprint        api.Fingerprint `db:"KeyFingerprint"`
	Expiry                api.Timestamp   `db:"Expiry"`
	Level                 uint8           `db:"Level"`
	ParentBoardCreation   api.Timestamp   `db:"ParentBoardCreation"`
	ParentBoardLastUpdate api.Timestamp   `db:"ParentBoardLastUpdate"`
}

type DbSubprotocol struct {
	Fingerprint       api.Fingerpr
    
func parseCommaSeparatedStringToStringSlice(str string, maxLen int, maxCount int) ([]string, error) {
	reader := csv.NewReader(strings.NewReader(str))
	result, err := reader.ReadAll()
	if err != nil {
		logging.LogCrash(err)
	}
	// Trim and check sanity.
	var cleaned []string
	var err2 error
	if result != nil { // If this isn't present, result[0] ends up undefined.
		for i, val := range result[0] {
			if i >= maxCount {
				// Too many items for the field. It's here, because otherwise somebody could send a 100 billion field string and brick the remote. We're still printing it, but not parsing it any more.
				return nil, errors.New(
					fmt.Sprintf(
						"The string provided has too many items. String: %#v\n", val))
			}
			if len(val) < maxLen && len(val) > 0 {
				cleaned = append(cleaned, strings.Trim(val, " "))
			} else if len(val) < maxLen { // The length of the string is zero.
				err2 = errors.New(
					fmt.Sprintf(
						"This string is empty. String: %#v\n", val))
			} else { // The string is longer than max length allowed for field.
				err2 = errors.New(
					fmt.Sprintf(
						"This string is too long for this field. String: %#v\n", val))
			}
		}
		err3 := checkDuplicatesInStringSlice(cleaned)
		if err3 != nil {
			return cleaned, err3
		}
	}
	return cleaned, err2
}