Ruby-on-rails – Rails ActiveRecord: validate single attribute

rails-activerecordruby-on-railsvalidation

Is there any way I can validate a single attribute in Rails?

Something like:

ac_object.valid?(attribute_name)

Best Answer

You can implement your own method in your model. Something like this

def valid_attribute?(attribute_name)
  self.valid?
  self.errors[attribute_name].blank?
end

Or add it to ActiveRecord::Base

Related Solutions

Javascript – Validate decimal numbers in JavaScript – IsNumeric()

@Joel's answer is pretty close, but it will fail in the following cases:

// Whitespace strings:
IsNumeric(' ')    == true;
IsNumeric('\t\t') == true;
IsNumeric('\n\r') == true;

// Number literals:
IsNumeric(-1)  == false;
IsNumeric(0)   == false;
IsNumeric(1.1) == false;
IsNumeric(8e5) == false;

Some time ago I had to implement an IsNumeric function, to find out if a variable contained a numeric value, regardless of its type, it could be a String containing a numeric value (I had to consider also exponential notation, etc.), a Number object, virtually anything could be passed to that function, I couldn't make any type assumptions, taking care of type coercion (eg. +true == 1; but true shouldn't be considered as "numeric").

I think is worth sharing this set of +30 unit tests made to numerous function implementations, and also share the one that passes all my tests:

function isNumeric(n) {
    return !isNaN(parseFloat(n)) && isFinite(n);
}

P.S. isNaN & isFinite have a confusing behavior due to forced conversion to number. In ES6, Number.isNaN & Number.isFinite would fix these issues. Keep that in mind when using them.

Update : Here's how jQuery does it now (2.2-stable):

isNumeric: function(obj) {
    var realStringObj = obj && obj.toString();
    return !jQuery.isArray(obj) && (realStringObj - parseFloat(realStringObj) + 1) >= 0;
}

Update : Angular 4.3:

export function isNumeric(value: any): boolean {
    return !isNaN(value - parseFloat(value));
}

Javascript – How to validate an email address in JavaScript

Using regular expressions is probably the best way. You can see a bunch of tests here (taken from chromium)

function validateEmail(email) {
    const re = /^(([^<>()[\]\\.,;:\s@"]+(\.[^<>()[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
    return re.test(String(email).toLowerCase());
}

Here's the example of regular expresion that accepts unicode:

const re = /^(([^<>()[\]\.,;:\s@\"]+(\.[^<>()[\]\.,;:\s@\"]+)*)|(\".+\"))@(([^<>()[\]\.,;:\s@\"]+\.)+[^<>()[\]\.,;:\s@\"]{2,})$/i;

But keep in mind that one should not rely only upon JavaScript validation. JavaScript can easily be disabled. This should be validated on the server side as well.

Here's an example of the above in action:

function validateEmail(email) {
  const re = /^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;
  return re.test(email);
}

function validate() {
  const $result = $("#result");
  const email = $("#email").val();
  $result.text("");

  if (validateEmail(email)) {
    $result.text(email + " is valid :)");
    $result.css("color", "green");
  } else {
    $result.text(email + " is not valid :(");
    $result.css("color", "red");
  }
  return false;
}

$("#email").on("input", validate);

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<label for=email>Enter an email address:</label>
<input id="email">
<h2 id="result"></h2>

Best Answer

Related Solutions

Javascript – Validate decimal numbers in JavaScript – IsNumeric()

Javascript – How to validate an email address in JavaScript

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