Showing posts with label Jquery. Show all posts
Showing posts with label Jquery. Show all posts

Sep 1, 2018

S3 Direct Upload Python Django

Using Pyhton Boto API, we can interact with Amazon S3 servers (for GET, PUT, POST etc)
We can also directly upload files to Amazon S3 from the client browser using Browser Uploads to S3 using HTML POST Forms.

Ref:
https://aws.amazon.com/articles/Java/1434

Prerequisites:
S3_BUCKET
S3_KEY
S3_SECRET
S3_URL

Note:
As per Amazon API, we need to encode policy format to base64 and further generate signature with SHA1
Both Policy and Signature need to be posted
Expiration : You can define the expiration time
acl: public-read/private
$key: upload path startes with
Check the POST S3 Url in HTML
Once the document is successfully uploaded to S3, S3 URL is shown on the page

Django Pyhton View:

import base64
import hmac, hashlib
import re

def direct_s3_upload(request):
  my_bucket = None
  policy_document = None
  policy_base_64 = signature = cors_xml = ""
  try:
    policy_document = '{"expiration": "2020-01-01T00:00:00Z", \
                       "conditions": [ \
                         {"bucket": "%s"}, \
                         {"acl": "public-read"}, \
                         ["starts-with", "$key", "uploads/"], \
                         ["content-length-range", 0, 524288000] \
                       ] \
                    }' % (<S3_BUCKET>)

    whitespace = re.compile(r'\s+')
    policy_document = whitespace.sub('', policy_document)
    policy_base_64 = base64.b64encode(whitespace.sub('', policy_document))
    signature = base64.b64encode(hmac.new(S3_SECRET, policy_base_64, hashlib.sha1).digest()) 
    dic1 = { 
           'MY_BUCKET_NAME': <S3_BUCKET>,
           'MY_AWS_KEY_ID': <S3_KEY>, 
           'MY_POLICY' : policy_base_64,
           'MY_SIGNATURE' : signature,
        }
  except:
    write_exception("direct_s3_upload")
  return render_to_response('test_s3_upload.html', context_instance=RequestContext(request, dic1))


HTML:  (test_s3_upload.html)
<html> 
  <head>
    <title>S3 POST Form</title> 
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
    <script>
      var bucketName = '{{MY_BUCKET_NAME}}';
      var AWSKeyId   = '{{MY_AWS_KEY_ID}}';
      var policy     = '{{MY_POLICY}}';
      var signature  = '{{MY_SIGNATURE}}';

      function S3ToolsClass() {
        var _handle_progress = null;
        var _handle_success  = null;
        var _handle_error    = null;
        var _file_name       = null;

        this.uploadFile = function(file, progress, success, error) {
          _handle_progress = progress;
          _handle_success  = success;
          _handle_error    = error;
          _file_name       = file.name;

          console.log(file.name)
          var fd = new FormData();
          fd.append('key', "uploads/" + file.name);
          fd.append('AWSAccessKeyId', AWSKeyId);
          fd.append('acl', 'public-read');
          fd.append('policy', policy);
          fd.append('signature', signature);
          fd.append("file",file);

          var xhr = new XMLHttpRequest({mozSystem: true});
          xhr.upload.addEventListener("progress", uploadProgress, false);
          xhr.addEventListener("load", uploadComplete, false);
          xhr.addEventListener("error", uploadFailed, false);
          xhr.addEventListener("abort", uploadCanceled, false);
          xhr.open('POST', 'https://s3.amazonaws.com/' + bucketName + '/');

          xhr.send(fd);
        }

        function uploadProgress(evt) {
          if (evt.lengthComputable) {
            var percentComplete = Math.round(evt.loaded * 100 / evt.total);
            _handle_progress(percentComplete);
          }
        }

        function uploadComplete(evt) {
          if (evt.target.responseText == "") {
            console.log("Upload complete - success") 
            _handle_success(_file_name);
          } else {
            console.log("Upload complete - not success") 
            _handle_error(evt.target.responseText);
          }
        }

        function uploadFailed(evt) {
          console.log("upload Failed")
          _handle_error("There was an error attempting to upload the file." + evt);
        }

        function uploadCanceled(evt) {
          console.log("upload cancelled")
          _handle_error("The upload has been canceled by the user or the browser dropped the connection.");
        }
      }
      var S3Tools = new S3ToolsClass();
      
      function uploadFile() {
        var file = document.getElementById('file').files[0];
        S3Tools.uploadFile(file, handleProgress, handleSuccess, handleError);
      }

      function handleProgress(percentComplete) {
        document.getElementById('progressNumber').innerHTML = percentComplete.toString() + '%';
      }

      function handleSuccess(fileName) {
        document.getElementById('progressNumber').innerHTML = 'Done!';
        document.getElementById('resultant_s3_url').innerHTML = 'https://s3.amazonaws.com/' + bucketName + '/uploads/' + fileName;
      }

      function handleError(message) {
        document.getElementById('progressNumber').innerHTML = 'Error: ' + message;
      }
    </script>
  </head>
  <body>
    <form id="form" enctype="multipart/form-data" method="post">
      <div class="row">
        1. Select a File<br>
        <input type="file" name="file" id="file"/>
      </div>
      <br>
      <div class="row">
        2. Upload File<br>
        <input type="button" onclick="uploadFile()" value="Upload" />
        <br/>
        <span id="progressNumber"></span>
      </div>
    </div>
    <br>
    <div class="row">
      3. Result S3 Url
      <br>
      <div id="resultant_s3_url"> </div>

    </div>
  </body>
</html>
Thank you for reading this article.

Jul 20, 2015

Jquery Examples

MAP
$.map([10,20,30], function(n,i) { return n+i;});   //[10, 21, 32]

Jquery Reverse Order of  Child Elements (ul & li):
var list = $('ul');
var listItems = list.children('li');
list.append(listItems.get().reverse());

$('ul li')[0]                       //<li>AAA</li>
$('ul li')[0].innerHTML  //AAA


$("ul li").eq(7).css("border", "1px solid #000000");  //Applies style to 8th element

Apply Style to Even & Odd rows:
$("ul  li:even").addClass("even");
$("ul  li:odd").addClass("odd");
(or)

$("ul li").each(function(i) {
if (i % 2 == 1)
{
    $(this).addClass("odd");    //$(this).css("background-color", 'red')
}
else
{
    $(this).addClass("even");   //$(this).css("background-color", 'yellow')
}
});

if ($('#elem').is(':hidden')) {
   // Do something conditionally
}

$('p:visible').hide();  // Hiding only elements that are currently visible
$('ul').siblings().length   //Siblings of <ul> element

To Get Immediate Children
<a href="/category">Category</a>
<ul id="nav">
<li><a href="#anchor1">Anchor 1</a></li>
<li><a href="#anchor2">Anchor 2</a></li>
<li><span><a href="#anchor3">Anchor 3</a></span></li>
</ul>

$('li > a').length => 2 (only in immediate direct children)
$('li a').length => 3 (all anchor tags )

$('li').children()
or
$('li > *')
or
$('li').find('> *')

Stop Event Bubbling:
return false; => event.stopPropagation(); + event.preventDefault();
event.stopImmediatePropagation(); => stops immediately without executing handlers of same element.
event.stopPropagation(); => stops executing handlers of parent elements, but executes that of same element

end()
You can return to the previous set of DOM elements that were selected before using a destructive method.

   <p>text 1 </p>
    <p class="test_class">text 2
        <span>AAA</span>
    </p>
    <p>text 3 </p>
   
    <script type="text/JavaScript"
    src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.min.js"></script>
    <script type="text/JavaScript">
        console.log($('p').filter('.test_class').length); // 1
        console.log($('p').filter('.test_class').end().length); // 3
        console.log($('p').filter('.test_class').find('span').end().end().length); // 3
    </script>

filter() vs find()
find() will operates the children of the current set
filter() will only operate on the current set of elements.

On the same level: (FILTER)
$('div').filter('.x').length
or
$('div.x').text()

Inner level search (FIND)
$('div').find('.x').length
or
$('div .x').text()

Jquery - Save File:
$('#ajax-loader').show();
            $.post("/test/return/data/", snddata,
                  function callbackHandler(data, textstatus){
                    $('#ajax-loader').hide();
                    if(data.status == 1){
                        str = data.encrypted_data
                        saveData(str, "download_file_name")
                    }
                    else{
                       alert(data.msg);
                    }
                 },
                 "json"
            );

var saveData = (function () {
        var a = document.createElement("a");
        document.body.appendChild(a);
        a.style = "display: none";
        return function (data, fileName) {
            var json = data,
                blob = new Blob([json], {type: "octet/stream"}),
                url = window.URL.createObjectURL(blob);
            a.href = url;
            a.download = fileName;
            a.click();
            window.URL.revokeObjectURL(url);
        };
      }());


&amp issues while passing from template to server
str = ''
document.location = '/test/url/' + encodeURIComponent(str);

!important
!important (It will override the CSS definition in header classes)
<style type="text/css">
   .bst_popover{
     max-width: 500px !important;
   }
</style>

Choose a specific parent
$(this).parents("tr:first");
$(this).closest("tr");


Jun 20, 2014

Django Example Project - Student Application

About Django Student Application
This student application achieves a reporting tool for subject and marks of the student
Based on the subject filtering, this application generates a brief report on student marks (Beautiful Pie Chart)

Download Application

Prerequisites
Python
Django
MySQL
HighCharts
Jqury

JavaScript Modules Used
Highcharts
Jquery

Steps to install Student Application
django-admin.py startproject StudentWebsite
python manage.py startapp StudentApp
python manage.py validate
python manage.py sqlall StudentApp

MySQL Database Details
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'studentsdb',                     
        'USER': 'XXXX',
        'PASSWORD': 'XXXX',
        'HOST': '127.0.0.1',                     
        'PORT': '3306',                
    }
}

Insert MySQL sample data
Note: You can either add the data from Admin page (one by one) or Load/Import sample "studentapp.sql" into database

Database Models Used:
Student
Subject
StudentMarks

How to start Django Development Server
Django develeopment server works on default port 8000
python manage.py runserver 8000

Access Home Page

http://127.0.0.1:8000/home/


How Application Looks
Select the desired subject

After selecting the subject as Physics - Generates the report as above































models.py

#-*- encoding=UTF-8 -*-
from django.db import models
from django.core.exceptions import ValidationError
import re

class Student(models.Model):
    firstname = models.CharField(max_length=30, null=False, blank=False)
    lastname = models.CharField(max_length=30, null=False, blank=False)

    def clean(self):
        if re.match(r'^\s+$', self.firstname):
            raise ValidationError('Firstname should contain some characters, only spaces not allowed')
        if re.match(r'^\s+$', self.lastname):
            raise ValidationError('Lastname should contain some characters, only spaces not allowed') 
 
    def __unicode__(self):
        return u'%s %s' % (self.firstname, self.lastname)

    class Meta:
        unique_together = (("firstname", "lastname"),)
        ordering = ['firstname']

class Subject(models.Model):
    name = models.CharField(max_length=10, unique=True, null=False, blank=False)
    
    def clean(self):
        if re.match(r'^\s+$', self.name):
            raise ValidationError('Subject should contain some characters, only spaces not allowed')
    
    def __unicode__(self):
        return u'%s' % (self.name)

class StudentMarks(models.Model):
    student = models.ForeignKey(Student)
    subject = models.ForeignKey(Subject)
    marks   = models.IntegerField(max_length=3, null=False, blank=False)

    class Meta:
        unique_together = (("student", "subject"),)  

urls.py

from django.conf.urls import patterns, include, url

# Uncomment the next two lines to enable the admin:
from django.contrib import admin
admin.autodiscover()

urlpatterns = patterns('',
    # Examples:
    # url(r'^$', 'StudentWebsite.views.home', name='home'),
    # url(r'^StudentWebsite/', include('StudentWebsite.foo.urls')),

    # Uncomment the admin/doc line below to enable admin documentation:
    url(r'^admin/doc/', include('django.contrib.admindocs.urls')),

    # Uncomment the next line to enable the admin:
    url(r'^admin/', include(admin.site.urls)),
)

urlpatterns += patterns('StudentWebsite.StudentApp.views',
 #url(r'^$', 'home'),
 url(r'^home/$', 'subjectView', name="home"),
    url(r'^getMarksDetailsView/(?P\w+)/$', 'getMarksDetailsView', name="getMarksDetailsView"),
)


views.py

#-*- encoding=UTF-8 -*-
from django.http import HttpResponse, HttpResponseRedirect, Http404
#from django.http import *
from django.shortcuts import render, render_to_response
from django.core.urlresolvers import reverse
from StudentWebsite.StudentApp.models import Subject, Student, StudentMarks
from django.db.models import Avg, Count

def subjectView(request):
    subjectList = Subject.objects.values('pk', 'name')
    side_bar = {'Home':'home', 'Admin' : 'admin:index'}
    return render(request, 'StudentsMain.html', {'subjects' : subjectList, 'side_bar' : side_bar})

def getMarksDetailsView(request, subjectName):
    subjectStudentDetails = StudentMarks.objects.filter(subject__name=subjectName).values('student__firstname', 'student__lastname', 'subject__name', 'marks')
    avgSubjectMarks = Subject.objects.filter(name=subjectName).annotate(average_rating=Avg('studentmarks__marks'))[0].average_rating
    side_bar = {'Home':'home', 'Admin' : 'admin:index'}
    ranges = [ '0-40', '41-60', '61-80', '81-90', '91-100']
    marksRange = {}
    for eachRange in ranges:
        count = StudentMarks.objects.filter(subject__name=subjectName).filter(marks__range=(eachRange.split('-'))).count()
        marksRange[eachRange] = count 
    return render(request, 'StudentSubjectDetails.html', {'subjectStudentDetails' : subjectStudentDetails, 'avgSubjectMarks' : avgSubjectMarks, 'side_bar' : side_bar, 'marksRange' : marksRange, 'subjectName' : subjectName.title() })


admin.py

from django.contrib import admin
from StudentWebsite.StudentApp.models import Student, Subject, StudentMarks

#This is just for dispaly order of columns for Author
class StudentAdmin(admin.ModelAdmin):
    list_display = ('firstname', 'lastname')
    search_fields = ('firstname', 'lastname')
    ordering = ('-firstname',)

class SubjectAdmin(admin.ModelAdmin):
    list_display = ('name',)
    list_filter = ('name',)
    ordering = ('-name',)
    fields = ('name',)

class StudentMarksAdmin(admin.ModelAdmin):
    list_display = ('student', 'subject', 'marks')
    list_filter = ('student', 'subject', 'marks')
    ordering = ('-student',)

admin.site.register(Student, StudentAdmin) #StudentAdmin is just for display in Admin page
admin.site.register(Subject, SubjectAdmin) #SubjectAdmin is just for display in Admin page
admin.site.register(StudentMarks, StudentMarksAdmin)