RosettaCodeData/Task/Simple-database/Nim/simple-database.nim

102 lines
2.2 KiB
Nim

import algorithm, json, os, strformat, strutils, times
const FileName = "simdb.json"
type
Item = object
name: string
date: string
category: string
Database = seq[Item]
DbError = object of CatchableError
proc load(): Database =
if fileExists(FileName):
let node = try: FileName.parseFile()
except JsonParsingError:
raise newException(DbError, getCurrentExceptionMsg())
result = node.to(DataBase)
proc store(db: Database) =
try:
FileName.writeFile $(%* db)
except IOError:
quit "Unable to save database.", QuitFailure
proc addItem(args: seq[string]) =
var db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
let date = now().format("yyyy-MM-dd HH:mm:ss")
let cat = if args.len == 2: args[1] else: "none"
db.add Item(name: args[0], date: date, category: cat)
db.store()
proc printLatest(args: seq[string]) =
let db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
if db.len == 0:
echo "No entries in database."
return
# No need to sort db as items are added chronologically.
if args.len == 1:
var found = false
for item in reversed(db):
if item.category == args[0]:
echo item
found = true
break
if not found:
echo &"There are no items for category '{args[0]}'"
else:
echo db[^1]
proc printAll() =
let db = try: load()
except DbError: quit getCurrentExceptionMsg(), QuitFailure
if db.len == 0:
echo "No entries in database."
return
for item in db:
echo item
proc printUsage() =
echo &"""
Usage:
{getAppFilename().splitPath().tail} cmd [categoryName]
add add item, followed by optional category
latest print last added item(s), followed by optional category
all print all
For instance: add "some item name" "some category name"
"""
quit QuitFailure
if paramCount() notin 1..3: printUsage()
var params = commandLineParams()
let command = params[0].toLowerAscii
params.delete(0)
case command
of "add":
if params.len == 0: printUsage()
addItem(params)
of "latest":
if params.len > 1: printUsage()
printLatest(params)
of "all":
if params.len != 0: printUsage()
printAll()