[Tutor] Writing logfile data to a user opened file

[Matt D]

On 06/21/2013 04:44 PM, Prasad, Ramit wrote:
> Matt D wrote:
>> [Ramit P wrote:]
>>> When you open a file the data should be written to that. If you want to
>>> move existing data from logfile.txt into user opened file then you need
>>> to read logfile.txt and then write it to the user opened file. To make
>>> your life simpler, either pass in the file path or open the file save
>>> dialog on __init__.
>>>
>>>
>>> ~Ramit
>>>
>> I got so frustrated try to figure a way to use the logfile.txt that I
>> changed how i log. first i name an array:
>>
>> class TrafficPane(wx.Panel):
>>     # Initializer
>>     # the class constructor
>>     def __init__(self, parent, msgq):
>>         wx.Panel.__init__(self, parent)
>>         self.msgq = msgq
>>         #create the array to put the traffic data in
>>         self.log_array = []
>>
>> Then this is how the array gets into the file the user chooses:
>>
>>   # openfile defined to start FileDialog
>>     def openFile(self, evt):
>>         with wx.FileDialog(self, "Choose a file", os.getcwd(), "",
>>                             "*.txt*", wx.OPEN) as dlg:
>>             if dlg.ShowModal() == wx.ID_OK:
>>                 path = dlg.GetPath()
>>                 #mypath = os.path.basename(path)
>>                 mypath = os.path.abspath(path)
>>                 f = open(mypath, "rw+")
> 
> Why are you opening the file in "rw+"? 
> 
>>                 f.writelines(self.log_array)
> 
> You should really switch to the "with open() as f:" idiom I keep showing 
> you. This will automatically close the file for you.
> 
> Also note that your file is only getting written once. You should
> probably clear log_array and change the file mode back to append.
> 
>>
>> And this is how i get the TextCtrl values into the array:
>>
>> def update(self, field_values):
>>         next_line = ""
>>         #logger code---------------
>>         #  first new line
>>         #self.logfile.write('\n')
>>         #  date and time
>>         #self.logfile.write('%s,'%(str(strftime("%Y-%m-%d %H:%M:%S",
>> localtime()))))
>>         next_line += (str(strftime("%Y-%m-%d %H:%M:%S", localtime())))
>>         #  loop through each of the TextCtrl objects
>>         for k,v in self.fields.items():
>>             #  get the value of the current TextCtrl field
>>             f = field_values.get(k, None)
>>             if f:
>>                 #  output the value with trailing comma
>>                 #self.logfile.write('%s,'%(str(f)))
>>                 next_line += (str(f) + ',')
>>         log_array.append(next_line)
>>         #end logger code----------
>>
>> Its running right now.  I haven't had the opportunity to test if it
>> works so im keeping my fingers crossed.
> 
> This is an inefficient string concatenation. It can take large amounts
> of memory and time. 
> 
> next_line += (str(f) + ',')
> 
> You can use str.join or use the csv module (which I recommend as it
> will escape the delimeter (eg. commas ) if it shows up in the data ).
> I have sent an example of the csv module already. Also note that
> your order of the dictionary is not guaranteed so your data
> may end up out of order after each run. 
> 
> 'hi', 1 , 5423
> 4255, 'hi', 2
> # instead of
> 1, 'hi', 5423
> 2, 'hi', 4255
> 
> # A str.join example 
> next_line = []
> for key in sorted( self.fields ):
>     f = field_values.get(k, None)
>     if f:
>         next_line.append(str(f))
> line = ', '.join(next_line)
> log_array.append(line)
> 
> 
> ~Ramit
Thanks!  so i went with:

# openfile defined to start FileDialog
    def openFile(self, evt):
        with wx.FileDialog(self, "Choose a file", os.getcwd(), "",
                            "*.txt*", wx.OPEN) as dlg:
            if dlg.ShowModal() == wx.ID_OK:
                path = dlg.GetPath()
                mypath = os.path.basename(path)
                #mypath = os.path.abspath(path)
                f = open(mypath, "a")
                f.writelines(self.log_array)

couldn't figure how to use the "with open() as f:"

and then down here:

# Update the field values
    # put values in array
    def update(self, field_values):
        next_line = ""
        next_line += strftime("%Y-%m-%d %H:%M:%S")
        next_line +=  ','.join( field_values[k] for k in
self.fields.keys() if k in field_values )
        log_array.append(next_line)

        #if the field 'duid' == 'hdu', then clear all the fields
        if field_values['duid'] == 'hdu':
            self.clear()
        #loop through all TextCtrl fields storing the key/value pairs in
k, v
        for k,v in self.fields.items():
                    # get the pickle value for this TextCtrl
            f = field_values.get(k, None)
                    # if the value is empty then set the new value
            if f:
                v.SetValue(f)


code definitely looks better but is its not working.  the TextCtrls are
not receiving their values anymore?  i cant tell why?