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• Trouble understanding XHR streams and express

  17 janvier 2017, par Jon

  I’m having some trouble understanding how I can trigger an XHR response from an express server res.write.

  I’m creating a request on the client with the following code :

   var xhr = new XMLHttpRequest();
  
  
  
   xhr.open(opts.method || 'get', url);
  
  
  
   for (var k in opts.headers||{}) {
  
     xhr.setRequestHeader(k, opts.headers[k]);
  
   }
  
  
  
   xhr.onload = e => res(e.target.responseText);
  
   xhr.onerror = rej;
  
  
  
   if (xhr.upload && progressCb) {
  
     xhr.upload.onprogress = progressCb;
  
   }
  
  
  
   xhr.send(opts.body);

  On the node server, I’m doing multiple res.write() in response to this request.

  For example, I’m creating a video using ffmpeg() and throughout the creation process, I’ll res.write() a JSON.stringified status update.

  The client will receive the last .write(), but the xhr.upload.onprogress callback is not triggered, so I don’t think I understand how to use it correctly. I’m guessing that the xhr.upload.onprogress is meant solely for callbacks related to uploading data to the server, not for triggering a response to multiple writes

  Is there a way for an XHR request to fire a callback every time it receives a res.write() from express ? If not, what’s a better way of achieving this goal ?

• How to plot an animated graph

  2 août 2019, par Mukonza Sabastian Simbarashe

  Following along How to Create Animated Graphs in Python when constructing an animated plot then on writing the ffmpeg I get the following error :

  'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available

  After getting this error, I initially tried to install ffmpeg using pip by the following method :

  python -m install ffmpeg

  and it seems to have successfully installed ffmpeg, but going back to my code I still get the same error

  Find below my code :

  import numpy as np
  
  import pandas as pd
  
  import seaborn as sns
  
  import matplotlib
  
  import matplotlib.pyplot as plt
  
  import matplotlib.animation as animation
  
  
  
  overdoses = pd.read_excel(r'C:\Users\ACER\Desktop\overdose_data_1999-2015.xls',sheet_name='Online',skiprows =6)
  
  
  
  def get_data(table,rownum,title):
  
      data = pd.DataFrame(table.loc[rownum][2:]).astype(float)
  
      data.columns = {title}
  
      return data
  
  
  
  title = 'Heroin Overdoses'
  
  d = get_data(overdoses,18,title)
  
  x = np.array(d.index)
  
  y = np.array(d['Heroin Overdoses'])
  
  overdose = pd.DataFrame(y,x)
  
  overdose.columns = {title}
  
  Writer = animation.writers['ffmpeg']

  Here is the stack trace :

  Traceback (most recent call last):
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 161, in __getitem__
  
      return self.avail[name]
  
  KeyError: 'ffmpeg'
  
  
  
  During handling of the above exception, another exception occurred:
  
  
  
  Traceback (most recent call last):
  
    File "", line 1, in <module>
  
      Writer = animation.writers['ffmpeg']
  
    File "C:\Python\Python36\lib\site-packages\matplotlib\animation.py", line 164, in __getitem__
  
      'Requested MovieWriter ({}) not available'.format(name))
  
  RuntimeError: Requested MovieWriter (ffmpeg) not available
  
  </module>

• Evolution #2923 : Remplacement d’un document et date du document

  21 mars 2013, par - Equipement

  Effectivement, sans attendre des changements éventuels dans SPIP, je modifie automatiquement (via un plugin) le champ "date" (et pas le champ "date de publication") lors du remplacement d’un document.