Chapters

1. 1. Validations Overview
2. 2. Validation Helpers
   1. 2.1. Presence
   2. 2.2. Inclusion
   3. 2.3. Exclusion
   4. 2.4. Format
   5. 2.5. Length

1. Validations Overview

Call Validates method in a record builder to enable validation for an attribute:

Product := activerecord.New("product", func(r *activerecord.R) {
    r.ValidatesPresence("name")
})

p := Product.New(activesupport.Hash{"name": nil})
p.IsValid() // false

As you can see, the Product record without name attribute is not valid.

2. Validation Helpers

A record builder aciverecord.R provides several helpful validators, further we will briefly describe all of them. For more details, please, refere to the API documentation.

2.1. Presence

This helper validates that value of the specified attribute is not blank. It uses activesupport.IsBlank method to make a validation. There are two ways to enable validation of the attribute. The first way is to use Validates method:

Product := activerecord.New("product", func(r *activerecord.R) {
    r.Validates("name", &activerecord.Presence{})
    r.Validates("category", &activerecord.Presence{AllowNil: true})
})

The second way is to use ValidatePresence method that accepts multiple attribute names:

Product := activerecord.New("product", func(r *activerecord.R) {
    r.ValidatesPresence("name", "category", "weight")
})

The default error message is can't be blank.

2.2. Inclusion

This helper validates that value of the specified attribute is available in a slice.

Movie := activerecord.New("movie", func(r *activerecord.R) {
    r.Validates("format", &activerecord.Inclusion{In: activesupport.Strings("mkv", "avi")})
})

The default error message is is not included in the list.

2.3. Exclusion

This helper validates that value of the specified attribute is not in the slice.

Zone := activerecord.New("Zone", func(r *activerecord.R) {
    r.Validates("name", &activerecord.Exclusion{From: activesupport.Strings("tk", "biz")})
})

The default error message is is reserved.

2.4. Format

This helper validates that value of the specified attribute match the regular expression.

Ticket := activerecord.New("ticket", func(r *activerecord.R) {
    r.Validates("reference", &activerecord.Format{With: `[A-Z]{3}-[0-9]{4}`})
})

Alternatively, you can request that attribute does not match the regular expression using Without parameter of Format helper.

Flight := activerecord.New("flight", func(r *activerecord.R) {
    r.Validates("destination", &activerecord.Format{Without: `[0-9]`})
})

The default error message is has invalid format.

2.5. Length

This helper validates that the attributes’ values comply with the specified length restrictions.

Book := activerecord.New("book", func(r *activerecord.R) {
    r.Validates("title", &activerecord.Length{Maximum: 50})
    r.Validates("abstract", &activerecord.Length{Minimum: 100, Maximum: 200})
})

The default error message when value is too short is is too short (minimum %d characters), when value is too long error with text is too long (maximum %d characters).