Community contributions, tips, and corrections to the documentation. (1708 notes)
We often have a form with a select box that selects a model association. So for example to select a colour, when there is an associated Colour model, a select box will typically select :colour_id.
In this case, ActionView automatically humanizes :colour_id to produce "Colour" as the label text.
== Example
File.foreach(filename)
.take(number_of_lines)
.map do |line|
# ... stuff ...
end
If you get this error, wrap brackets with parentheses: Post.find_by_sql(["some query"])
number_field_tag does not accept the size or maxlength options; the max option for number_field_tag is used to control the size of the field. According to W3 http://www.w3.org/TR/html-markup/input.number.html , placeholder should be accepted, but I don't find that this works in the way it works for...
Consider the following:
foo = Foo.new
bar = Bar.new
ActiveRecord::Base.transaction do
foo.save! # succeeds
bar.save! # failure, validation problem
end
foo.persisted? # true (!)
foo was not permanently stored in the database, but it was transiently saved, and this...
Consider the following:
ActiveRecord::Base.transaction do
foo = Foo.new
foo.save # succeeds
bar = Bar.new
bar.save # failure, validation problem
end
as you can see in InstanceTag
a.fetch(1) == a.at(1) #=> true
To clarify on the last comment, conceptually it's the same, but #flat_map will perform better because there is no need to create an intermediate Array
"split(p1 = v1, p2 = v2)"
in reading the rest of the documentation, i found "p1" and "p2" to be confusing.
I think it should be:
split( pattern, limit )
exclude? is defined as !include?, meaning it is the exact opposite of include? . See the source.
This means that it works for Arrays and Hashes too, as well as for Strings.
It works for Arrays:
>> [nil].exclude?(nil)
=> false
>> [nil].include?(nil)
=> true
>> ["lala"].i...
adding to stevo's comment that reorder is also usefull when you have default scope in your model. eg: default_scope -> { order(created_at: :desc) }
Why is the example showing the use of the #detect method and not #find? Boggles the mind!
If you're looking to redirect to a subdomain you can do things like this:
redirect_to users_url(1, params: {a: :b}, subdomain: 'bob')
Anyone knows?
If you need the method to be called at the beginning of the before_filter chain then you should use:
prepend_before_filter
After creating a simple Maybe monad in Ruby, a colleaque noticed I could have just used try (I wasn't aware try supports blocks). I think the method was even meant for such cases.
Why I mention this? Because it clarifies the whole 'raises exception if method does not exist' thing. It should not be...
This simplistic implementation (unlike Marshal.load(Marshal.dump(object)) doesn't handle cycles in objects.
a = {}
b = {a: a}
a[:b] = b
a.deep_dup # SystemStackError: stack level too deep
A default pretty printing method for general objects. It calls pretty_print_instance_variables to list instance variables.
If self has a customized (redefined) inspect method, the result of self.inspect is used but it obviously has no line break hints.
This module provides predefined pretty_print...