I am new to CherryPy. I am using the default dispatcher, with a URL structure similar to this:
root = Root()
root.page1 = Page1()
root.page1.apple = Apple()
root.page2 = Page2()
root.page2.orange = Orange()
Orange renders a template, in which I need a link to Apple. I could just hardcode /page1/apple/. But how can I get the URL of Apple in a DRY manner?
Can this be done with the default dispatcher in CherryPy, or is it only possible with the Routes dispatcher?
(I am coming from the Django world, where one would use reverse() for this purpose.)
You can access to the mounted apps through
cherrypy.tree.apps[mount_point].root
root is always the mounted instance to the mount point. So a reverse function would look like:
def reverse(cls):
# get link to a class type
for app_url in cherrypy.tree.apps.keys():
if isinstance(cherrypy.tree.apps[app_url].root, cls):
# NOTE: it will return with the first mount point of this class
return app_url
Please find a sample code below that uses your classes. http://localhost:8080/page4/orange/ prints out { Orange and the link to apple: : "/page3/apple" }
import cherrypy
link_to_apple_global = ''
class Orange(object):
def __init__(self):
pass
#cherrypy.expose
#cherrypy.tools.json_out()
def index(self):
return {"Orange and the link to apple: ": link_to_apple_global}
class Page2(object):
def __init__(self):
pass
#cherrypy.expose
def index(self):
return "Page2"
class Apple(object):
def __init__(self):
pass
#cherrypy.expose
def index(self):
return "Apple"
class Page1(object):
def __init__(self):
pass
#cherrypy.expose
def index(self):
return "Page1"
class Root(object):
def __init__(self):
pass
#cherrypy.expose
def index(self):
return "Root"
def reverse(cls):
#return cherrypy.tree.apps.keys()
#return dir(cherrypy.tree.apps[''].root)
#return dir(cherrypy.tree.apps['/page3/apple'].root)
# get link to apple
for app_url in cherrypy.tree.apps.keys():
if isinstance(cherrypy.tree.apps[app_url].root, cls):
# NOTE: it will return with the first instance
return app_url
root = Root()
root.page1 = Page1()
root.page1.apple = Apple()
root.page2 = Page2()
root.page2.orange = Orange()
cherrypy.tree.mount(root, '/')
# if you do not specify the mount points you can find the objects
# in cherrypy.tree.apps[''].root...
cherrypy.tree.mount(root.page1, '/page4')
cherrypy.tree.mount(root.page2, '/page3')
cherrypy.tree.mount(root.page2.orange, '/page4/orange')
cherrypy.tree.mount(root.page1.apple, '/page3/apple')
link_to_apple_global = reverse(Apple)
cherrypy.engine.start()
cherrypy.engine.block()
Related
So I have two files, one called a.rb and one called b.rb. Here's the contents in both:
# a.rb
class A
def initialize
#variable = ""
#module_b = B.new(self)
end
def pass_to_b(self)
#module_b.do_something(#variable)
end
def set_variable(var)
# var = empty
#variable = var
end
end
and
# b.rb
class B
def initialize(module_a)
#module_a = module_a
end
def set_variable_in_a(data)
#module_a.set_variable(data)
end
def do_something(variable)
# variable = empty
set_variable_in_a("hello world")
end
end
This is just an example of what I'm dealing with. If I'm trying to start a function in Class A, which is supposed to do something in ClassB and then change an instance variable in Class A, I'm not sure how to do this properly. This is what I've tried, however:
a = A.new
a.pass_to_b
Class B cannot see the instance variable #variable, and if it tries to set_variable_in_a, that doesn't work either. It's like the do_something function in Class A successfully calls the do_something function in Class B, but the instance variable information is not available. I thought by passing self to Class B, we'd be able to at least call the function
My MRI throws exeption about
def pass_to_b(self)
because you can't pass self to method as argument.
You need delete 'self' how argument
Run code below and you will see that #variable of instance of Class A has '123hello world' string
class A
def initialize
#variable = "123"
#module_b = B.new(self)
end
def pass_to_b
#module_b.do_something(#variable)
end
def set_variable(var)
# var = empty
#variable = var
end
end
# b.rb
class B
def initialize(module_a)
#module_a = module_a
end
def set_variable_in_a(data)
#module_a.set_variable(data)
end
def do_something(variable)
set_variable_in_a(variable + "hello world")
end
end
a = A.new
a.pass_to_b
display variable 'a' and you will see something like this
#<A:0x00007fdaba0f3c90 #variable="123hello world", #module_b=#<B:0x00007fdaba0f3c40 #module_a=#<A:0x00007fdaba0f3c90 ...>>>
I am trying to access variable in ruby after initialize, but i didn't get that variable , anything wrong in that?
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def self.method1(params)
Test.new(params)
#can i get that two instance variable
end
end
You should probably set up attribute accessors, then use them this way:
class Test
attr_accessor :has_test
attr_accessor :limit_test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def self.method1(params)
t = Test.new(params)
// can i get that two instance variable
// Yes:
// use t.has_test and t.limit_test
end
end
You are mixing an instance and a class method in your example.
If this is really what you want, then you have to define an accessor with attr_reader:
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
attr_reader :has_test
attr_reader :limit_test
def self.method1(params)
obj = Test.new(params)
p obj.has_test
p obj.limit_test
end
end
Test.method1(has_test: 1, limit_test: 3)
It the instance/class-method is a mistake, then this example may help you:
class Test
def initialize(params)
#has_test = params[:has_test]
#limit_test = params[:limit_test]
end
def method1()
p #has_test
p #limit_test
end
end
obj = Test.new(has_test: 1, limit_test: 3)
obj.method1
If you define also the accessors like in the first code, then you have again access from outside the class.
Just in case you don't want a reader, see also Access instance variable from outside the class
I have a custom class in my application controller. Like below:
class Defaults
def initialize
#value_1 = "1234"
#value_2 = nil
#data = Data.new
end
end
class Data
def initialize
#data_1 = nil
end
end
Now in my controller method i have created an object of type Defaults
def updateDefaultValues
defaults = Defaults.new
# i am unable to update the value, it says undefined method
defaults.value_2 = Table.maximum("price")
defaults.data.data_1 = defaults.value_2 * 0.3
end
How to access value_2 from defaults object?
defaults.value_2
Also, how to access data_1 attribute from data object within defaults object?
defaults.data.data_1
You should use attr_accessor:
class Defaults
attr_accessor :value_1, :value_2, :data
# ...
end
defaults = Defaults.new
defaults.value_1 = 1
# => 1
defaults.value_1
# => 1
As you are using def as a keyword to define the method, that means def is a reserved keyword. You can't use reserved keywords as a variable.
You just need to rename your variable name from def to something_else and it should work! Your code will look like this:
def updateDefaultValues
obj = Defaults.new
obj.value_2 = Table.maximum("price")
obj.data.data_1
end
EDIT:
As per OP's comment & updated question, he had used def just as an example, here is the updated answer:
You may need attr_accessor to make attrs accessible:
class Defaults
attr_accessor :value_1, :value_2, :data
...
...
end
class Data
attr_accessor :data_1
...
...
end
Add value_2 method in Defaults class
class Defaults
def initialize
#value_1 = "1234"
#value_2 = nil
#data = Data.new
end
def value_2
#value_2
end
end
class Data
def initialize
#data_1 = nil
end
end
I trying to build a dynamic query similar to:
def domain = DomainName
def ids = 1
def domainClass = "$domain" as Class
domainClass.find("from ${domain} as m where m.job = ${ids} ").id
But it's not working.
If I'm trying this, all is fine:
def domain = DomainName
def ids = 1
DomainName.find("from ${domain} as m where m.job = ${ids} ").id
How can I use dynamic domain class name with find?
The simplest way is to use the getDomainClass method:
String domainClassName = 'com.foo.bar.Person'
def ids = 1
def domainClass = grailsApplication.getDomainClass(domainClassName).clazz
domainClass.find("from $domainClassName as m where m.job = ${ids} ").id
Note that if you're trying to get a single instance by id, use get:
long id = 1234
def person = domainClass.get(id)
and if you want to get multiple instances and you have a list of ids, you can use getAll
def ids = [1,2,3,4,5]
def people = domainClass.getAll(ids)
Also it's a REALLY bad idea to use GStrings with property values embedded - Google 'SQL Injection'
For example to find a person by username:
String username = 'foo'
def person = domainClass.find(
"from $domainClassName as m where m.username=:username",
[username: username])
You should be able to do this by explicitly using the GroovyClassLoader:
def domain = "DomainName"
def c = new GroovyClassLoader().loadClass(domain)
c.find('...').id
The best way to get a Domain class dynamically is through the GrailsApplication object. Example:
import org.codehaus.groovy.grails.commons.ApplicationHolder
def domainName = "full.package.DomainName"
def domainGrailsClass = ApplicationHolder.application.getArtefact("Domain", domainName)
def domainClass = domainGrailsClass.getClazz()
domainClass.find("from ${domainGrailsClass.name} as m where m.job = ${ids}").id
You can also use Class.forName() just as you would in Java. Use the 3 parameter version and pass in the current thread context class loader:
import grails.util.GrailsNameUtils
def domainName = "full.package.DomainName"
def domainClass = Class.forName(domainName, true, Thread.currentThread().getContextClassLoader())
domainClass.find("from ${GrailsNameUtils.getShortName(domainName)} as m where m.job = ${ids}").id
Classloaders are an ugly topic in Java and JVM frameworks. In Grails, you almost always want to use the thread context classloader. But even better is to use the GrailsApplication interface and avoid the issue altogether.
use GrailsClassUtils
GrailsClassUtils.getShortName(DomainName)
to get the name of the class, so this should work... if I understood the question
def domainClassName = GrailsClassUtils.getShortName(DomainName)
def ids = 1
DomainName.find("from ${domainClassName} as m where m.job = ${ids} ").id
I have the following models:
class Message(models.Model):
date = models.DateTimeField()
user = models.ForeignKey(User)
thread = models.ForeignKey('self', blank=True, null=True)
...
class Forum(models.Model):
name = models.CharField(max_length=24)
messages = models.ManyToManyField(Message, through="Message_forum", blank=True, null=True)
...
class Message_forum(models.Model):
message = models.ForeignKey(Message)
forum = models.ForeignKey(Forum)
status = models.IntegerField()
position = models.IntegerField(blank=True, null=True)
tags = models.ManyToManyField(Tag, blank=True, null=True)
In the admin site, when I go to add/change a forum, I don't see the messages listbox as you'd expect. However, it shows up if I remove the 'through' parameter in the ManyToManyField declaration. What's up with that? I've registered all three models (plus Tag) to the admin site in admin.py.
TIA
Documentation says:
When you specify an intermediary model using the through argument to a
ManyToManyField, the admin will not display a widget by default.
But it's probably possible to display M2M fields in the admin change view even if the through attribute is defined.
class ForumAdminForm(forms.ModelForm):
mm = forms.ModelMultipleChoiceField(
queryset=models.Message.objects.all(),
widget=FilteredSelectMultiple(_('ss'), False, attrs={'rows':'10'}))
def __init__(self, *args, **kwargs):
if 'instance' in kwargs:
initial = kwargs.setdefault('initial', {})
initial['mm'] = [t.service.pk for t in kwargs['instance'].message_forum_set.all()]
forms.ModelForm.__init__(self, *args, **kwargs)
def save(self, commit=True):
instance = forms.ModelForm.save(self, commit)
old_save_m2m = self.save_m2m
def save_m2m():
old_save_m2m()
messages = [s for s in self.cleaned_data['ss']]
for mf in instance.message_forum_set.all():
if mf.service not in messages:
mf.delete()
else:
messages.remove(mf.service)
for message in messages:
Message_forum.objects.create(message=message, forum=instance)
self.save_m2m = save_m2m
return instance
class Meta:
model = models.Forum
class ForumAdmin(admin.ModelAdmin):
form = ForumAdminForm
Take a look at the official documentation:
I learned a lot from #Fedor's answer, but some comments and cleanup may be still beneficial.
class ForumAdminForm(forms.ModelForm):
messages = forms.ModelMultipleChoiceField(
queryset=Message.objects.all(),
widget=FilteredSelectMultiple('Message', False))
# Technically, you don't need to manually set initial here for ForumAdminForm
# However, you NEED to do the following for MessageAdminForm
def __init__(self, *args, **kwargs):
if 'instance' in kwargs:
# a record is being changed. building initial
initial = kwargs.setdefault('initial', {})
initial['messages'] = [t.message.pk for t in kwargs['instance'].message_forum_set.all()]
super(ForumAdminForm, self).__init__(*args, **kwargs)
def save(self, commit=True):
if not self.is_valid():
raise HttpResponseForbidden
instance = super(ForumAdminForm, self).save(self, commit)
def save_m2m_with_through():
messages = [t for t in self.cleaned_data['messages']
old_memberships = instance.message_forum_set.all()
for old in old_memberships:
if old.message not in messages:
# and old membership is cleaned by the user
old.delete()
for message in [x for x in messages not in map(lambda x: x.message, old_memberships)]:
membership = Member_forum(message=messsage, forum=instance)
# You may have to initialize status, position and tag for your need
membership.save()
if commit:
save_m2m_with_through()
else:
self.save_m2m = save_m2m_with_through
return instance
class Meta:
model = Forum
fields = {'name', 'messages')
There's one caveat: if you have another many-to-many relationship in the models (that is without through), super(ForumAdminForm, self).save(self, commit) will set self.save_m2m in case commit is False. However, calling this would cause an error, because this function also tries to save the many-to-many with through as well. You may need to save all other many-to-many relationship manually, or catch the exception, or else.
Django admin nicely support many-to-many intermediary models that using the through argument .
For example you have these Person and Group models with intermediate Membership model:
models.py
from django.db import models
class Person(models.Model):
name = models.CharField(max_length=128)
class Group(models.Model):
name = models.CharField(max_length=128)
members = models.ManyToManyField(Person, through='Membership')
class Membership(models.Model):
person = models.ForeignKey(Person, on_delete=models.CASCADE)
group = models.ForeignKey(Group, on_delete=models.CASCADE)
date_joined = models.DateField()
invite_reason = models.CharField(max_length=64)
Now in admin.py file ,
Define an inline class for the intermediate Membership model:
#admin.register(Membership)
class MembershipInline(admin.TabularInline):
model = Membership
extra = 1
And use them in admin views of models:
#admin.register(Person)
class PersonAdmin(admin.ModelAdmin):
inlines = (MembershipInline,)
#admin.register(Group)
class GroupAdmin(admin.ModelAdmin):
inlines = (MembershipInline,)
More info in official docs:
Models,
Admin