Having 15-year experience in web development, I have tried my hands at dozens of validation libraries but didn’t manage to find the one to handle all my tasks. 5 years ago we decided to create a validator which will better than any other. Now LIVR supports a dozen of programming languages and it is battle tested in hudrends of projects. I will talk about the ideas behind, about architecture, use cases, pros and cons. Will show real examples.

1. Language Independent Validation
Rules (LIVR) 2.0
Viktor Turskyi
CEO at WebbyLab

2. Viktor Turskyi
● CEO and principal architect at
WebbyLab
● Open source developer
● More than 15 years of experience
● Delivered more than 60 projects of
different scale
● Did projects for 5 companies from
Fortune 500 list

4. Joi size
https://github.com/jeffbski/joi-browser

5. 7 years ago we decided to create own
data validation library

6. Why?

7. 10 issues of existing validators

8. Issue 1: Some validators pass through fields
which have no validation rules described
Issue 2: Some validators fails on the first error

9. Issue 3: Some validators use procedural rules
Issue 4: Some validators describe validation as a
code

10. Issue 5: Some validators have non standardized
error messages.
Like “Field name is required”
Issue 6: Some validators have numeric error
codes

11. Issue 7: Some validators do not support
hierarchical data structures
Issue 8: Some validators are limited by built-in
rules

12. Issue 9: Some validators have to broad
responsibility. Like working with HTML etc
Issue 10: Some validators do not support
transformation of validation data

13. How?

14. Example: validate registration data

15. LIVR Specification 2.0
http://livr-spec.org/

17. Battle tested Test Suite for
implementations

18. LIVR - Mustache in the
world of Data Validation

19. What is Mustache? o_O

22. Example: validate registration data

23. Syntax details
# Short form
password: [ 'required', {min_length: 10} ]
# Full form
password: [ {required: [ ] }, { min_length: [10] } ]

24. Example: validate nested object

25. Example: validate list

26. Example: validate list of objects

27. Example: output modification (pipelines)

28. IMPLEMENTATION

29. Small universal core, all features are in rules
For the core there is no difference between:
‘required’, ‘nested_object’, ‘trim’.

30. Aliased Rules

31. Custom rules

32. Using LIVR for REST API
Request: POST /users

33. Response which looks better than “Bad request” :)

34. JS Implementation features
● Zero dependencies
● Passes 100% of spec tests
● Works in NodeJs and in a browser
● Validator itself 1008 B (min+gzip)
● Validator with all rules 2.84KB (min+gzip)
● Extra rules pack - livr-extra-rules (zero deps)

36. Links
● LIVR Specification
● LIVR Playground
● Universal test suite
● LIVR - Data Validation Without Any Issues

37. Telegram: @JABASCRIPT

38. Viktor Turskyi
viktor@webbylab.com
@koorchik @koorchik
https://webbylab.com