How do you check if an array contains a value in Ruby?
To check if a value is in the array, you can use the built-in include? method. The include? method returns true if the specified value is in the array and false if not.
How do I check if an array is nil Ruby?
Just do if @a == [“”]? If it is an array, then it is not nil .
What is the opposite of include in Ruby?
exclude? is defined as ! include?, meaning it is the exact opposite of include? . See the source.
What is IS_A in Ruby?
The is_a? method will return a true value if an object is a of the type given as a parameter OR if it inherits from the type given as a parameter. So in effect, you can use it to ask “is there going to be a method from a class which I can run on this object”.
How do I check if an object is nil in Ruby?
In Ruby, you can check if an object is nil, just by calling the nil? on the object… even if the object is nil. That’s quite logical if you think about it 🙂 Side note : in Ruby, by convention, every method that ends with a question mark is designed to return a boolean (true or false).
Is nil or empty Ruby?
# nil? can be used on any Ruby object. It returns true only if the object is nil. # empty? can be used on some Ruby objects including Arrays, Hashes and Strings. It returns true only if the object’s length is zero.
Why we use include in Rails?
Rails provides an ActiveRecord method called :includes which loads associated records in advance and limits the number of SQL queries made to the database. This technique is known as “eager loading” and in many cases will improve performance by a significant amount.
What is difference between joins and include in Rails?
Includes uses eager loading whereas joins uses lazy loading. Both are used when certain operations are meant to be performed on associated tables. And here comes the difference.
How do you check for the opposite of not true in Ruby?
But when you want to check for the opposite “not true” (false) there is two things you can do. You can reverse the value with !. Or you can use unless, which is like if, but it checks for “not true”: Remember, using unless in Ruby is just the reverse of using if.
How do you use if statements in Ruby?
If something is true (the condition) then you can do something. In Ruby, you do this using if statements: stock = 10 if stock < 1 puts “Sorry we are out of stock!”
What is the difference between if and unless in Ruby?
Ruby programmers (usually coming from other languages) tend to prefer the use if !condition. On the other side, unless is widely use in case there is a single condition and if it sounds readable. Also see making sense with Ruby unless for further suggestions about unless coding style.
What is the difference between Elif and else if in Ruby?
The values false and nil are false, and everything else are true. Notice Ruby uses elsif, not else if nor elif. Executes code if the conditional is true. If the conditional is not true, code specified in the else clause is executed. An if expression’s conditional is separated from code by the reserved word then, a newline, or a semicolon.