activerecord - Ruby, use of '?' - db or model method? -



activerecord - Ruby, use of '?' - db or model method? -

i love using ? boolean fields, e.g, 'animals' table "alive?" obvious. define this? name db field when creating table migration(don't think so). or automatic boolean fields or have little method in active record model class animals says def alive? if live true else false end ?

rails automatically generates method ending in ? each of fields in model. examples:

animal #=> animal(id: integer, alive: boolean, name: string) = animal.new a.alive #=> nil a.alive? #=> false a.alive = true a.alive? #=> true a.name #=> nil a.name? #=> false a.name = "giraffe" a.name? #=> true

also note can define own ? methods:

class animal def young? created_at > 1.day.ago end end

ruby-on-rails activerecord

Comments

Post a Comment

Popular posts from this blog

java - How to pass parameters between Request-Scoped Controllers? -

java - How to pass parameters between Request-Scoped Controllers? - i have simple jsf-page , want pass parameter page1 page2. every page has own controller in request scope. the 2 controllers this: controller1: @component("requestcontroller1") @scope("request") public class requestcontroller1 { private list<product> products; private product selectedproduct; @postconstruct public void init() { //load products db } public void setproducts(list<product> products) { this.products = products; } public list<product> getproducts() { homecoming products; } public void setselectedproduct(product selectedproduct) { this.selectedproduct = selectedproduct; } public product getselectedproduct() { homecoming selectedproduct; } controller2: @component("requestcontroller2") @scope("request") public class requestcontroller2 { private long selectedproductid; @postconstruct public void init() ...
Read more

string - what is the difference between "some" == "some\0" and strcmp("some","some\0") in c++? -

string - what is the difference between "some" == "some\0" and strcmp("some","some\0") in c++? - what difference between "some" == "some\0" , strcmp("some","some\0") in c++? why if("some" == "some\0") returns false , if(!strcmp("some","some\0")) returns true ? see next diagram. shows 2 strings in memory, content in box, beside box you'll see address of each one. when you're doing if("some" == "some\0") comparing addresses. translated if (0xdeadbeef == 0x0badcafe) false. when utilize strcmp , compare content of each box until reach \0 in each of them. that's why sec test returns true. if alter first test if("some" == "some") compiler may potentially see same strings , store them once. means test transform if (0x0badcafe == 0x0badcafe) true. c++ string comparison
Read more

actionscript 3 - Flex: moving a point with rotation doesnt change the point XY? -

actionscript 3 - Flex: moving a point with rotation doesnt change the point XY? - i have follow issue : i have point setted @ border on component, changed transform point center of component in order match component rotation. the of import part when seek point xy after rotation - remains same before rotation. how xy, after rotation ( changeing point.rotation property specific degrees of rotaion ) if want point after rotation, cos(r) * x, sin(r) * y easiest way. if want point after transformations, should able utilize displayobject.transform.transformpoint(x, y) . there's displayobject.localtoglobal . in case phone call localtoglobal(x, y) , localtoglobal(0, 0) , calculate difference. see transform livedocs , displayobject livedocs flex actionscript-3
Read more