我试图表达这样的条件:
if 33.75 < degree <= 56.25
# some code
end
但是Ruby给出了这个错误:
undefined method `<=' for true:TrueClass
我猜测一种方法是这样的:
if 33.75 < degree and degree <= 56.25
# code
end
但是没有另一种更简单的方法吗？
我猜测如何只检索数据库中所有记录的名称.简单的方法是这样的:
@user=User.all
@list=[]
@user.each do|u|
@list.push(u.name)
end
但我确定它是否必须是irb的oneline查询必须适合.有没有人有想法？
嗨,我是Angular2的新手,当我尝试使用onicial angular.io网站上的示例运行npm测试时,我收到此错误:
providers[name][0] is not a function
TypeError: providers[name][0] is not a function
at get (/Users/marcpursals/repos/..../node_modules/di/lib/injector.js:48:43)
at /Users/marcpursals/repos/...../node_modules/di/lib/injector.js:71:14
at Array.map (native)
at Injector.invoke (/Users/marcpursals/repos/...../node_modules/di/lib/injector.js:70:31)
at Server.start (/Users/marcpursals/repos/....node_modules/karma/lib/server.js:103:18)
at Promise (/Users/marcpursals/repos/..../node_modules/@angular/cli/tasks/test.js:35:25)
at Class.run (/Users/marcpursals/repos/..../node_modules/@angular/cli/tasks/test.js:15:16)
at Class.run (/Users/marcpursals/repos/....node_modules/@angular/cli/commands/test.js:99:25)
at Class.<anonymous> (/Users/marcpursals/repos/...../node_modules/@angular/cli/ember-cli/lib/models/command.js:134:17)
at process._tickCallback (internal/process/next_tick.js:103:7)
npm ERR! Test failed. See above for more details.
我正在使用angular 4.0.1,我的package.json是下一个:
"dependencies": {
"@angular/animations": "^4.0.1",
"@angular/common": "^4.0.1",
"@angular/compiler": "^4.0.1",
"@angular/compiler-cli": "^4.0.1",
"@angular/core": "^4.0.1",
"@angular/forms": "^4.0.1",
"@angular/http": "^4.0.1",
"@angular/material": "^2.0.0-beta.2",
"@angular/platform-browser": "^4.0.1",
"@angular/platform-browser-dynamic": "^4.0.1",
"@angular/platform-server": "^4.0.1",
"@angular/router": "^4.0.1",
"@ng-bootstrap/ng-bootstrap": …我有这个sample_data.rake文件:
namespace :db do
desc "Fill Patients with sample data"
task populate: enviroment do
Patient.create!(name: ["Example", "User"],
email: "example@gmail.com"
password: "foobar"
password_confirmation: "foobar"
age: "26"
doctor_id: "3"
dao: "true"
active: "true")
350.times do |n|
name=Faker::Name.name
email = "example-#{n+1}@gmail.com"
password = "password"
age = (25...45).sample
doctor_id = [2,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22].sample
dao = ["true", "false"].sample
active = "true"
Patient.create!(name: name,
email: email,
password: password,
password_confirmation: password,
age: age,
doctor_id: doctor_id
dao: dao,
active: active)
end
end
end
它放在lib/tasks上,当我运行rake db:populate我收到下一个错误.
rake aborted!
Don't know how …我想知道是否有最性感的方式进行双重迭代,我的意思是,我有两次迭代在同一个关系上,如下所示:
bars = ActiveRecord::Relation [.....]
bars.each do |bar|
do_something1(bar)
do_something2(bar)
end
bars.each do |bar|
do_something3(bar)
do_something4(bar)
end
显而易见的答案是:
bars.each do |bar|
do_something1(bar)
do_something2(bar)
do_something3(bar)
do_something4(bar)
end
但实际上我真的需要先完成do_something1(bar)和do_something2(bar),然后在同一关系上执行do_something3(bar)和do_something4(bar).可能这是一个新手问题,但我尝试的任何东西都比这更难.有什么建议吗？
提前致谢.
更新:对不起,我忘了说我已经尝试了这个:
bars.each do |bar|
do_something1(bar)
do_something2(bar)
end.each do |bar|
do_something3(bar)
so_something4(bar)
end
但是在代码理解方面,很容易理解第一个和改进它只是一个词,这是我没有使用它的方式.
我是Rails的新手,我刚刚完成了我正在开发的应用程序的一部分,我想知道数据库文件在哪里,我无法在rails.root目录中找到它.有没有人有答案？
提前致谢.
编辑:我正在搜索文件而不是配置文件,我正在使用PostgreSQL和Ubuntu
我是新手,我想知道是否可以用params定义模型方法.我的意思是.我有这种方法用球坐标计算距离
#in my model
#Haversin formula to calculate distance between spherical coordinates
def self.distance(b)
rad_per_deg = Math::PI/180 # PI / 180
rkm = 6371 # Earth radius in kilometers
#rm = rkm * 1000 # Radius in meters
a=[]
a.push(self.lat)
a.spuh(self.long)
dlon_rad = (b[1]-a[1]) * rad_per_deg # Delta, converted to rad
dlat_rad = (b[0]-a[0]) * rad_per_deg
lat1_rad, lon1_rad = a.map! {|i| i * rad_per_deg }
lat2_rad, lon2_rad = b.map! {|i| i * rad_per_deg }
a = Math.sin(dlat_rad/2)**2 + Math.cos(lat1_rad) * …