In my game, I have an __init__ function which creates a set of seven entry boxes, like so:
self.string1 = StringVal()
self.entry1 = Entry(frame, textvariable = self.string1).grid(row = 4, column = 1, sticky = W)
This is copied six more times. This works.
At the end of the game, though, I want to delete the Entry box's text, using this code I found several places online:
self.entry1.delete(0, END)
I also tried using something else I found:
if self.entry1.get():
self.entry1.delete(0, END)
These both say that self.entry1 is a NoneType object, and has no method .get() or .delete(). Just to try things out, I substituted self.entry1.get() and self.entry1.delete(0,END) with self.string1.get(), etc. I also tried substituting .delete(0, END) with .delete(0.0, END). Neither of these worked either. I do not understand what I am doing wrong.
Thanks for your help!
When you do something like this:
self.foo = Button(...).grid(...)
... Then what gets stored in self.foo is the result of the call to grid(). This will always be None. You need to separate your widget creation from the loyout in order to save a reference to the created widgets.
Related
I am new to Ruby, so let me describe the context of my problem first:
I have a json as input which has the following key / value pair:
{
"service": "update"
}
The value has many different values for example: insert,delete etc.
Next there is a method x which handles the different requests:
def x(input)
case input[:service]
services = GenericService.new
when "update"
result = services.service(UpdateService.new,input)
when "insert"
result = services.service(InsertService.new,input)
when "delete"
result = services.service(DeleteService.new,input)
....
....
else
raise "Unknown service"
end
puts JSON.pretty_generate(result)
end
What is bothering me is that I still need to use a switch statement to check the String values (reminds me of 'instance of' ugh..). Is there a cleaner way (not need to use a switch)?
Finally I tried to search for an answer to my question and did not succeed, if however I missed it feel free to comment the related question.
Update: I was thinking to maybe cast the string to the related class name as follows: How do I create a class instance from a string name in ruby? and then call result = services.services(x.constantize.new,input) , then the class names ofcourse needs to match the input of the json.
You can try something like:
def x(input)
service_class_name = "#{input[:service].capitalize}Service"
service_class = Kernel.const_get(service_class_name)
service_class.new(input).process
end
In addition you might want to check if this is a valid Service class name at all.
I don't understand why you want to pass the service to GenericService this seems strange. let the service do it's job.
If you're trying to instatiate a class by it's name you're actually speaking about Reflection rather than Polymorphism.
In Ruby you can achieve this in this way:
byName = Object.const_get('YourClassName')
or if you are in a Rails app
byName= 'YourClassName'.constantize
Hope this helps
Just first thoughts, but you can do:
eval(services.service("#{input[:service].capitalize}Service.new, #{input})") if valid_service? input[:service]
def valid_service?
w%(delete update insert).include? input[:service]
end
As folks will no doubt shout, eval needs to be used with alot of care
I'm fairly new to programming so please be patient with me. I'm trying to create a simple script in Autodesk Maya. I've created a method that sets up two check-boxes side by side (See below)...
def checkboxLayout(self, name1, text1, name2, text2, parentLayout, initState):
##create and add horizontal layout
layout = QtGui.QHBoxLayout()
parentLayout.addLayout(layout)
width = 75
name1 = QtGui.QCheckBox(text1)
layout.addWidget(name1)
name1.setMinimumWidth(width)
name1.setMaximumWidth(width)
name1.setChecked(initState)
name2 = QtGui.QCheckBox(text2)
layout.addWidget(name2)
name2.setMinimumWidth(width)
name2.setMaximumWidth(width)
And later on I've called this method twice in order to save me having to write out the same big block of code twice...
def createLayout(self):
##Layout
mainLayout = QtGui.QVBoxLayout()
mainLayout.addWidget(self.title)
mainLayout.addSpacerItem(self.titleSpacer)
mainLayout.addWidget(self.oldLabel)
self.checkboxLayout("selection_CB", "Selection", "name_CB", "Name", mainLayout, True)
mainLayout.addWidget(self.textbox1)
mainLayout.addSpacerItem(self.midSpacer)
mainLayout.addWidget(self.newLabel)
mainLayout.addWidget(self.textbox2)
self.checkboxLayout("delHistory_CB", "Delete\nHistory", "freezeTrans_CB", "Freeze\nTransforms", mainLayout, False)
self.buttonLayout = QtGui.QGridLayout()
mainLayout.addLayout(self.buttonLayout)
self.buttonLayout.addWidget(self.cancelButton, 0, 0)
self.buttonLayout.addWidget(self.okButton, 0, 1)
self.setLayout(mainLayout)
My problem is that when I try to connect a signal to it, it won't work. All the tutorials I've watched so far have only connected signals to widgets that WERE NOT created by calling a method inside another method (I realize that probably isn't the correct terminology but like I said, I'm new to this :( ) I'll post the code that I've written to try and connect the signal below. My guess was that I had to specify the method that created the check box, but I couldn't get that to work either. So how do I get this signal connected? Also feel free to correct my terminology :) Thanks to anyone who can help :)
def createConnections(self):
self.selection_CB.toggled.connect(self.checkboxLine1_ChangeState)
Where and how are you setting the variable self.selection_CB?
In your checkboxLayout function you can include a return for your check box like so:
`return [name1, name2]`
then simply assign them as you're calling the function and connect the events from there:
self.check1, self.check2 = self.checkboxLayout("selection_CB", "Selection", "name_CB", "Name", mainLayout, True)
Or if they are always being connected to the same functions, then why not just do the connection straight from checkboxLayout?
name1.stateChanged.connect(self.checkboxLine1_ChangeState)
How do I create an object if one is not found? This is the query I was running:
#event_object = #event_entry.event_objects.find_all_by_plantype('dog')
and I was trying this:
#event_object = EventObject.new unless #event_entry.event_objects.find_all_by_plantype('dog')
but that does not seem to work. I know I'm missing something very simple like normal :( Thanks for any help!!! :)
find_all style methods return an array of matching records. That is an empty array if no matching records are found. And an empty is truthy. Which means:
arr = []
if arr
puts 'arr is considered turthy!' # this line will execute
end
Also, the dynamic finder methods (like find_by_whatever) are officially depreacted So you shouldn't be using them.
You probably want something more like:
#event_object = #event_entry.event_objects.where(plantype: 'dog').first || EventObject.new
But you can also configure the event object better, since you obviously want it to belong to #event_entry.
#event_object = #event_entry.event_objects.where(plantype: 'dog').first
#event_object ||= #event_entry.event_objects.build(plantype: dog)
In this last example, we try to find an existing object by getting an array of matching records and asking for the first item. If there are no items, #event_object will be nil.
Then we use the ||= operator that says "assign the value on the right if this is currently set to a falsy value". And nil is falsy. So if it's nil we can build the object form the association it should belong to. And we can preset it's attributes while we are at it.
Why not use built in query methods like find_or_create_by or find_or_initialize_by
#event_object = #event_entry.event_objects.find_or_create_by(plantype:'dog')
This will find an #event_entry.event_object with plantype = 'dog' if one does not exist it will then create one instead.
find_or_initialize_by is probably more what you want as it will leave #event_object in an unsaved state with just the association and plantype set
#event_object = #event_entry.event_objects.find_or_initialize_by(plantype:'dog')
This assumes you are looking for a single event_object as it will return the first one it finds with plantype = 'dog'. If more than 1 event_object can have the plantype ='dog' within the #event_entry scope then this might not be the best solution but it seems to fit with your description.
EDIT
The problem was with something else so the trouble wasn't really Qt, still I don't know why this happened.
The thing was that in the method display_filesize #yt.get_filesize(row_id, format) I used Nokogiri to parse the XML. I don't know if the XML was corrupted (it was loaded from quvi), but it was definitely the culprit. After switching to XMLSimple everything works fine.
The code I used:
def get_filesize(video_id, format)
video = #videos[video_id]
if video.formats[format].empty?
to_parse = `quvi --xml --format #{format} #{video.player_url}`
parsed = Nokogiri.parse(to_parse)
video.formats[format] = { :size => parsed.at('length_bytes').text,
:url => parsed.at('link').at('url').text }
end
video.formats[format][:size]
end
Now I use something like this:
def get_filesize(video_id, format)
video = #videos[video_id]
if video.formats[format].empty?
to_parse = `quvi --xml --format #{format} #{video.player_url}`
parsed = XmlSimple.xml_in(to_parse, {'KeyAttr' => 'name'})
video.formats[format] = { :size => parsed['link'][0]['length_bytes'][0],
:url => URI.decode(parsed['link'][0]['url'][0]) }
end
video.formats[format][:size]
end
It works beautifully. Still, I don't know why it crashed. This is the real question.
OLD QUESTION
I have a Qt::TableView that contains Qt::StandardItemModel. A row in the model consists of text, Qt::PushButton, checkbox and Qt::ComboBox. It works like this:
The user is presented with text values and can explore further if they want to.
The user clicks Qt::PushButton and the next cell is populated with a Qt::ComboBox containing other possible values to choose from.
If the user chooses an option from Qt::ComboBox, magic happens, objects get created, hashes populated and the cell on the right gets populated with appropriate text (through a Qt::StandardItem)
Then the checkbox can be checked.
After selecting the rows the user wants, a Qt::PushButton located outside of the Qt::TableView can be clicked. It then iterates through the model, tests if the checkbox is selected and should it be, tries to access the value in the appropriate ComboBox.
The problem is, when I insert code that tries to access the Qt::ComboBox, I can't insert the Qt::StandardItem, because I can't get the model, because Qt::TableView.model returns NilClass (at some point).
I don't know why and how this happens. It's a random thing, sometimes the value of Qt::ComboBox can be changed a couple times, sometimes the first try ends with an error.
Here is how I create the Qt::StandardItem:
def display_filesize
row_id = row_id_from_object_name(sender.objectName)
format = sender.currentText
filesize = #yt.get_filesize(row_id, format) # get the text
filesize_item = Qt::StandardItem.new("#{(filesize.to_i/1024/1024)} MB ")
# #tc simply stores the indexes of columns so I can access them easily
#ui.tableView.model.setItem(row_id, #tc[:filesize], filesize_item)
end
And here is how I try to access the Qt::ComboBox value:
model = #ui.tableView.model
checked = model.rowCount.times.map do |i|
if model.item(i, #tc[:check]).checkState == Qt::Checked
# if I remove the following two lines it works...
index = model.index(i, #tc[:formats])
format = #ui.tableView.indexWidget(index).currentText
#yt.videos[i][format]
end
end
And this is the error I am trying to get rid of:
searcher.rb:86:in `display_filesize': undefined method `index' for nil:NilClass (NoMethodError)
from /var/lib/gems/1.9.1/gems/qtbindings-4.8.3.0/lib/Qt/qtruby4.rb:469:in `qt_metacall'
from /var/lib/gems/1.9.1/gems/qtbindings-4.8.3.0/lib/Qt/qtruby4.rb:469:in `method_missing'
from /var/lib/gems/1.9.1/gems/qtbindings-4.8.3.0/lib/Qt/qtruby4.rb:469:in `exec'
from qutub-player.rb:17:in `<main>'
I have a collection of objects. There are 3 properties in each object
'id', 'name', 'is_primary'
The collection of objects will usually have anywhere from 1 to 5 objects.
What I want to do is check the collection to see if is_primary is true. If so output the name, or at least return it.
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all. I thought I had it, but if I return nil it adds extra space which shifts all the html oddly.
Thanks.
Hmm, this doesn't quite work if no element is_primary...I'm still thinking...
c.detect(&:is_primary).name
Ok, how about:
((a = c.detect(&:is_primary)) && a.name).to_s
As it happens, it is OK in an erb template for the <%= expression to return nil, that just results in an empty string, so for that case you can use:
(a = c.detect(&:is_primary)) && a.name
Update: Responding to the first comment, I do have a test case that I didn't post...
class A; attr_accessor :is_primary, :name, :id; end
t = [A.new, A.new, A.new, (a = A.new; a.name = 'xyz'; a.is_primary = true; a)]
puts (a = t.detect(&:is_primary)) && a.name
puts ((a = [].detect(&:is_primary)) && a.name).to_s
Complementing #DigitalRoss, you can also write:
collection.detect(&:is_primary).try(:name) || "default_if_no_element_or_name"
(well, to be honest I prefer Ick's maybe over Rails' try: c.detect(&:is_primary).maybe.name)
Side note: IMHO a flag that can only be active for a row it's not such a good idea. You may have inconsistent states with more than one being active and you'll have worry about it when updating (transactions, and so on). Try to store the PK reference somewhere else (a parent model? a state model?).
I want to do this in 1 line of code if possible. I am trying to slim up this one line for erb output in rails. Later in the page i'll output them all.
No need for one-liners (funny since I just wrote one): move the code to yous models or helpers as appropriate and keep your views pristine.