A simple, not flexible, mediocre performance Object Fields Validator

Features

• based on pragma and macro
• tags to group/filter validation rules
  • compile-time: tagsFilter expr
  • runtime: filterTags params
• custom validation function
• custom validation error message
• nested validation

TODO

• i18n validation error message

pragmas

{.valid: @[built-in rules].} for built-in validation rules

{.validFn(fn="function name").} for custom validation function

{.validate: "tag filter expr".} for marking a proc as validation proc

built-in validation rules

rules	for types	usage	description
nonNil	ref | ptr | pointer | cstring	a {.valid: @[nonNil()].}: ptr int	not nil
nonEmpty	string | array | set | seq	a {.valid: nonEmpty().}: string	len > 0
nonBlank	string	a {.valid: @[nonBlank()].}: string	not isEmptyOrWhiteSpace, use std/strutils
range	int	a {.valid: @[range(min=1, max=10)].}: int	int range
frange	float	a {.valid: @[frange(min=1,max=10)].}: float	float range
length	string | array | set | seq	a {.valid: @[length(min=1,max=10)].}: string	length range

usage

Note

Due to use std/strutils, std/sequtils in generated code, you should import them where you use {.validate.}

• code:

import validate
import std/[sequtils, strutils]

type Category = ref object
  name {.valid: @[length(min = 2)].}: string

type Status = enum
  onsale
  sold

proc isHttpUrl(v: string): bool =
    v.startswith("http://")

type Book = object
  # {.validFn.} use custom validate function
  url {.validFn(fn = "isHttpUrl", tags = ["show"], msg = "the url is not http url").}: string
  # nested validation
  category {.valid: @[nonNil()].}: Category
  tags {.valid: @[length(min = 2, max = 4, tags = ["show"])].}: seq[string]
  # msg template interpolation: $min and $max
  price {.valid: @[frange(min = 5, max = 50, tags = ["hide"], msg = "the price requires from $min to $max")].}: float
  # support object variants
  case status: Status
  of onsale, sold:
    count {.valid: @[range(min = 100, tags = ["hide"])].}: int

# validate book with filterTags
proc validate(book: Book, filterTags: varargs[string]): ValidateResult {.validate: "".}

# validate book with tagFilterExpr
proc validateWithTagFilterExpr(book: Book): ValidateResult {.validate: """ it in ["default","show","hide"] """.}


let category = Category(name: "T")
let book = Book(
    url: "ftp://127.0.0.1/books/1.pdf",
    category: category,
    tags: @["nim"],
    price: 52'd,
    status: onsale,
    count: 10,
)

# let validateResult = book.validate("default", "show", "hide")
let validateResult = book.validateWithTagFilterExpr()
for error in validateResult.errors:
    echo error

• output:

the url is not http url
Book.category.name: require match range `2 .. 9223372036854775807`
Book.tags: require match range `2 .. 4`
the price requires from 5.0 to 50.0
Book.count: require match range `100 .. 9223372036854775807`

benchmark

bench.nim

root in validate/bench on  main [✘?] via 👑 v2.0.2
❯ ./bench filterTags
len: 1000000
tag filter method: filterTags
result: 1.203444μs/op

root in validate/bench on  main [✘?] via 👑 v2.0.2
❯ ./bench tagFilterExpr
len: 1000000
tag filter method: tagFilterExpr
result: 1.186805μs/op