Valium

Android library to validate forms

Download

// build.gradle
allprojects {
    repositories {
        ...
        maven { url 'https://jitpack.io' }
    }
}

// app/build.gradle
dependencies {
    ...
    implementation 'com.github.graf-semmel:valium:0.4'
}

Example

// in your activity or fragment
val form = form {
    inputField(R.id.et_first_name) {
        rules {
            notBlank()
            min(3)
            max(100)
        }
    }
    inputField(R.id.et_last_name) {
        rules {
            notBlank()
            min(3)
            max(100)
        }
    }
    inputField(R.id.et_email) {
        rules {
            notBlank()
            isEmail()
        }
    }
    submitButton(R.id.btn_submit)
    onValidationChange { /* isValid -> viewModel.onFormValidationChange(isValid) */ }
}

Mark fields as optional

inputField {
    required = false
}

Custom error message

rules {
    notBlank(R.string.my_not_blank)
    min(3, R.string.my_too_short)
}

Extend validation rules

// extend Rule interface or ValidatorRule class if you want to use Validators
class EmailRule(@StringRes errorStringRes: Int = R.string.validation_error_email) : ValidatorRule(
    Validators.EmailValidator(),
    errorStringRes
)

// extend Rules class and register new rule
fun Rules.isEmail(@StringRes errorStringRes: Int = R.string.validation_error_email) = registerRule(EmailRule())

// add to rules
inputField(R.id.et_email) {
    rules {
        isEmail()
    }
}

Custom validators

Validators will be implemented by extending the Validator interface

interface Validator {
    fun validate(value: String): Boolean
}

Default validators

Common validators are provided under the Validators class

object Validators {
    class NotBlankValidator : Validator {
        override fun validate(value: String) = value.isNotBlank()
    }

    class MaxLengthValidator(private val max: Int) : Validator {
        override fun validate(value: String) = isNotNegative(max) && value.length <= max
    }
    ...
}

Change error displaying strategy

If you want to change the events that triggers the displaying of errors, overwrite the settings of the showErrors attribute. By default the errors will be shown when the user leaves the field he typed into. While typing their will be no error displayed when it is the first edit for a field.

If the form is linked to a submit button, any click on the submit button will trigger form validation and causes the displaying of potential errors. The possible settings are shown in the example below.

form {
    inputField(R.id.et_1_show_errors) {
        rules {
            notBlank()
            min(3)
        }
        showErrors { // will overwrite global validation strategy for a single field
            onFirstEdit = false
            onSubsequentEdit = true
            onLeaveField = true
        }
    }
    showErrors { // global validation strategy for a form
        onFirstEdit = false // when user types into field the very first time
        onSubsequentEdit = true // when user left the field and comes back to change its input
        onLeaveField = true // when user clicks into the next field
    }
}

TODO

• spinner field
• checkbox
• more rules
• move package to Maven Central