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How to Validate

Data Input in Your

Rails App

Melissa Holmes

Rails Girls Atlanta - October 2014

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in other words...

Melissa Holmes

Rails Girls Atlanta - October 2014

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Let’s Validate...

Melissa Holmes

Rails Girls Atlanta - October 2014

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Who am I?

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Who am I?

Melissa Holmes

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Who am I?

Melissa Holmes

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Last year I switched from being a C++ programmer to working on web apps.

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Who am I?

Melissa Holmes

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Last year I switched from being a C++ programmer to working on web apps.

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Currently I’m a Ruby on Rails & Sinatra developer at Rentpath.

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Who am I?

Other interests:

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Who am I?

Other interests:

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Art/Drawing Gardening

Cats (all kinds) Knitting

Coffee & tea Reading

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Validate?

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Validate?

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Our goal as developers:

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Our goal as developers:

Don’t use or save invalid data.

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Why?

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The user must provide necessary and

properly formatted information needed to successfully complete an operation.

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Why?

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What?

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Validate (a) required fields, (b) format correctness, and (c) confirmation fields.

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What?

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How?

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Determine the expected format.

Apply appropriate rules in your code.

How?

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Where?

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Server-side: Model, Database

Client-side: Browser (View)

Where?

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Server-side: ActiveRecord Model

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Validations are written in the model’s .rb file

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Server-side: ActiveRecord Model

Advantages

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  1. Easy to maintain and understand
  2. Custom validation methods can be used
  3. Validation check built in for standard methods such as save and create
  4. Provides a second level of validation for critical data

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Server-side: ActiveRecord Model

Disadvantages

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  1. Active record does not enforce validation in all contexts or for all methods
  2. Passing validate: false to save skips validation
  3. Rails' uniqueness validator cannot guarantee uniqueness

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Server-side: Database

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Validations are written in migrations

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Server-side: Database

Advantages

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  1. Enforces uniqueness consistently and correctly
  2. Provides a second level of validation for critical data

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Server-side: Database

Disadvantages

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  1. Must access database (expensive and slow)
  2. May respond with an error that must be handled if the data is invalid
  3. Limited validation rules

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Client-side: Browser (HTML)

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Validations are written in view files

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Client-side: Browser (HTML)

Advantages

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  1. Uses native browser checks
  2. Fastest option

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Client-side: Browser (HTML)

Disadvantages

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  1. Can be bypassed by user
  2. Support varies by browser
  3. Look and feel varies by browser

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Demo!

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Demo!

validations_demo

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Bonus Slides

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Client-side: jQuery

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Validations are written in javascript files

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Client-side: jQuery

Advantages

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  1. Reusable validation helpers
  2. Ability to do custom validation
  3. Less dependent on browser
  4. Faster than server-side validation

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Client-side: jQuery

Disadvantages

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  1. Javascript!
  2. Can be disabled by user
  3. Can be bypassed by user

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Demo!

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Demo!

jQuery-Mask-Plugin

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Questions?

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Server-side Sources

Server

Coding Rails with Data Integrity, Part 1

Coding Rails with Data Integrity, Part 2

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Model

ActiveRecord Validations

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Client-side Sources

Browser

Web Form Validation: Best Practices and Tutorials

HTML5 Form Validation

New HTML5 Form Input Helpers

HTML Attributes

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jQuery

jQuery Masked Input

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Contact me!

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