This gem looks at the schema for any validations that it can easily apply based on known db constraints and adds application level validations for them

A simple set of validations I got tired of writing over and over and over again.

Performs k-fold cross-validation on machine learning classifiers.

Adds active-record validations to a json format (to_arson) so that validations can be performed client side.

Hints for validation.

Serializes ActiveRecord validations into JSON for use by rich-client apps.

Ardm fork of dm-validations

An ActiveModel extension for more expressive validations reflection

Provides an extensible hook for adding custom html attributes to input elements based on validation rules defined in your model.

Tracks each validation error, providing an aggregate to identify UI issues

Mount to an endpoint of your application, give it forms fields, and it'll return the validations errors/success in JSON. Really usefull when you want to add on-unblur or before-submit validations.

Client Side Validations

Simple validation of params with a concern

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Additional validations for Active Model

Use database validations and convert ActiveRecord::StatementInvalid into ActiveRecord::RecordInvalid

Validation of complex structures

A parser which converts dry-validation contract schema into a readable hash for further manipulation

ActiveRecord::StrictValidations adds validations to ActiveRecord models to make sure they do not trigger database errors.

Declarative parameter definition and validation for Rails