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Flask

Image Upload

The following sections describe how to handle image uploads on your server using Flask as a server-side language. For information on the upload workflow refer to the image upload documentation.

Frontend

Setting up the index page.

  1. On the head section include the Editor style.

  2. <!DOCTYPE html>
        <html>
        <head>
        <meta charset="utf-8">
        
        <link href="https://cdn.jsdelivr.net/npm/froala-editor@latest/css/froala_editor.pkgd.min.css" rel="stylesheet" type="text/css" />
        </head>
  3. On the body section include the Editor JS files and define the area for the editor.

  4.     <body>  
        <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/froala-editor@latest/js/froala_editor.pkgd.min.js"></script>
        
        <div class="sample">
        <h2>image upload example.</h2>
        <form>
        <textarea id="edit" name="content"></textarea>
        </form>
        </div>
        
  5. Initialize the editor and set the image upload URL

  6.     <script>
        new FroalaEditor('#edit', {
        // Set the image upload URL.
        imageUploadURL: '/UploadFiles',
        
        imageUploadParams: {
        id: 'my_editor'
        }
        })
        </script>
        </body>
        </html>

The full code should look like this:

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8">
    <link href="https://cdn.jsdelivr.net/npm/froala-editor@latest/css/froala_editor.pkgd.min.css" rel="stylesheet" type="text/css" />
    </head>
    
    <body>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/froala-editor@latest/js/froala_editor.pkgd.min.js"></script>
    
    <div class="sample">
    <h2>image upload example.</h2>
    <form>
    <textarea id="edit" name="content"></textarea>
    </form>
    </div>
    
    
    <script>
    new FroalaEditor('#edit', {
    
    imageUploadURL: '/UploadFiles',
    
    imageUploadParams: {
    id: 'my_editor'
    }
    })
    </script>
    </body>
    </html>

The full code should look like this:

<!DOCTYPE html>
    <html>
    <head>
    <meta charset="utf-8">
    <link href="https://cdn.jsdelivr.net/npm/froala-editor@latest/css/froala_editor.pkgd.min.css" rel="stylesheet" type="text/css" />
    </head>
    
    <body>
    <script type="text/javascript" src="https://cdn.jsdelivr.net/npm/froala-editor@latest/js/froala_editor.pkgd.min.js"></script>
    
    <div class="sample">
    <h2>Image upload example.</h2>
    <form>
    <textarea id="edit" name="content"></textarea>
    </form>
    </div>
    
    
    <script>
    new FroalaEditor('#edit', {
    
    imageUploadURL: '/UploadFiles',
    
    imageUploadParams: {
    id: 'my_editor'
    }
    })
    </script>
    </body>
    </html>

Backend

server.py handles the server part for flask

Inside server.py, the Image class handles the image upload

from flask import Flask, request, send_from_directory, jsonify
  import base64
  import datetime
  from os.path import isfile, join
  from mimetypes import MimeTypes
  from os import listdir
  from wand.image import Image
  import wand.image
  import hashlib
  import json
  import time
  import hmac
  import copy
  import sys
  import os
  
  import wand.image
  
  # Create public directory at startup.
  BASE_DIR = os.path.dirname(os.path.abspath(__file__))
  publicDirectory = os.path.join(BASE_DIR, "public")
  if not os.path.exists(publicDirectory):
  os.makedirs(publicDirectory)
  
  app = Flask(__name__, static_url_path = "")
  
  @app.route("/")
  def get_main_html():
  return send_from_directory("./", "index.html")
  
  @app.route("/public/<path:path>")
  def get_public(path):
  return send_from_directory("public/", path)
  
  @app.route("/static/<path:path>")
  def get_static(path):
  return send_from_directory("./", path)
  
  @app.route("/upload_image", methods = ["POST"])
  def upload_image():
  try:
  response = Image.upload(FlaskAdapter(request), "/public/")
  except Exception:
  response = {"error": str(sys.exc_info()[1])}
  return json.dumps(response)
  
  @app.route("/upload_image_validation", methods = ["POST"])
  def upload_image_validation():
  def validation(filePath, mimetype):
  with wand.image.Image(filename = filePath) as img:
   if img.width != img.height:
       return False
   return True
  
  options = {
  "fieldname": "myImage",
  "validation": validation
  }
  
  try:
  response = Image.upload(FlaskAdapter(request), "/public/", options)
  except Exception:
  response = {"error": str(sys.exc_info()[1])}
  return json.dumps(response)
  
  
  class Image(object):
  
  defaultUploadOptions = {
  "fieldname": "file",
  "validation": {
   "allowedExts": ["gif", "jpeg", "jpg", "png", "svg", "blob"],
   "allowedMimeTypes": ["image/gif", "image/jpeg", "image/pjpeg", "image/x-png", "image/png",
                        "image/svg+xml"]
  },
  # string resize param from http://docs.wand-py.org/en/0.4.3/guide/resizecrop.html#transform-images
  # Examples: "100x100", "100x100!". Find more on http://www.imagemagick.org/script/command-line-processing.php#geometry
  "resize": None
  }
  
     @staticmethod
  def upload(req, fileRoute, options = None):
  """
  Image upload to disk.
  Parameters:
   req: framework adapter to http request. See BaseAdapter.
   fileRoute: string
   options: dict optional, see defaultUploadOptions attribute
  Return:
   dict: {link: "linkPath"}
  """
  
  if options is None:
   options = Image.defaultUploadOptions
  else:
   options = Utils.merge_dicts(Image.defaultUploadOptions, options)
  
  return File.upload(req, fileRoute, options)
  
     @staticmethod
  def delete(src):
  """
  Delete image from disk.
  Parameters:
   src: string
  """
  return File.delete(src)
  
     @staticmethod
  def list(folderPath, thumbPath = None):
  """
  List images from disk.
  Parameters:
   folderPath: string
   thumbPath: string
  Return:
   list: list of images dicts. example: [{url: "url", thumb: "thumb", name: "name"}, ...]
  """
  
  if thumbPath == None:
   thumbPath = folderPath
  
  # Array of image objects to return.
  response = []
  
  absoluteFolderPath = Utils.getServerPath() + folderPath
  
  # Image types.
  imageTypes = Image.defaultUploadOptions["validation"]["allowedMimeTypes"]
  
  # Filenames in the uploads folder.
  fnames = [f for f in listdir(absoluteFolderPath) if isfile(join(absoluteFolderPath, f))]
  
  for fname in fnames:
   mime = MimeTypes()
   mimeType = mime.guess_type(absoluteFolderPath + fname)[0]
  
   if mimeType in imageTypes:
       response.append({
           "url": folderPath + fname,
           "thumb": thumbPath + fname,
           "name": fname
       })
  
  return response
  
  
  class Utils(object):
  """
  Utils static class.
  """
  
     @staticmethod
  def hmac(key, string, hex = False):
  """
  Calculate hmac.
  Parameters:
   key: string
   string: string
   hex: boolean optional, return in hex, else return in binary
  Return:
   string: hmax in hex or binary
  """
  
  # python 2-3 compatible:
  try:
   hmac256 = hmac.new(key.encode() if isinstance(key, str) else key, msg = string.encode("utf-8") if isinstance(string, str) else string, digestmod = hashlib.sha256) # v3
  except Exception:
   hmac256 = hmac.new(key, msg = string, digestmod = hashlib.sha256) # v2
  
  return hmac256.hexdigest() if hex else hmac256.digest()
  
     @staticmethod
  def merge_dicts(a, b, path = None):
  """
  Deep merge two dicts without modifying them. Source: http://stackoverflow.com/questions/7204805/dictionaries-of-dictionaries-merge/7205107#7205107
  Parameters:
   a: dict
   b: dict
   path: list
  Return:
   dict: Deep merged dict.
  """
  
  aClone = copy.deepcopy(a);
  # Returns deep b into a without affecting the sources.
  if path is None: path = []
  for key in b:
   if key in a:
       if isinstance(a[key], dict) and isinstance(b[key], dict):
           aClone[key] = Utils.merge_dicts(a[key], b[key], path + [str(key)])
       else:
           aClone[key] = b[key]
   else:
       aClone[key] = b[key]
  return aClone
  
     @staticmethod
  def getExtension(filename):
  """
  Get filename extension.
  Parameters:
   filename: string
  Return:
   string: The extension without the dot.
  """
  return os.path.splitext(filename)[1][1:]
  
     @staticmethod
  def getServerPath():
  """
  Get the path where the server has started.
  Return:
   string: serverPath
  """
  return os.path.abspath(os.path.dirname(sys.argv[0]))
  
     @staticmethod
  def isFileValid(filename, mimetype, allowedExts, allowedMimeTypes):
  """
  Test if a file is valid based on its extension and mime type.
  Parameters:
   filename string
   mimeType string
   allowedExts list
   allowedMimeTypes list
  Return:
   boolean
  """
  
  # Skip if the allowed extensions or mime types are missing.
  if not allowedExts or not allowedMimeTypes:
   return False
  
  extension = Utils.getExtension(filename)
  return extension.lower() in allowedExts and mimetype in allowedMimeTypes
  
     @staticmethod
  def isValid(validation, filePath, mimetype):
  """
  Generic file validation.
  Parameters:
   validation: dict or function
   filePath: string
   mimetype: string
  """
  
  # No validation means you dont want to validate, so return affirmative.
  if not validation:
   return True
  
  # Validation is a function provided by the user.
  if callable(validation):
   return validation(filePath, mimetype)
  
  if isinstance(validation, dict):
   return Utils.isFileValid(filePath, mimetype, validation["allowedExts"], validation["allowedMimeTypes"])
  
  # Else: no specific validating behaviour found.
  return False
  
  
  class BaseAdapter(object):
  """
  Interface. Inherit this class to use the lib in your framework.
  """
  
  def __init__(self, request):
  """
  Constructor.
  Parameters:
   request: http request object from some framework.
  """
  self.request = request
  
  def riseError(self):
  """
  Use this when you want to make an abstract method.
  """
  raise NotImplementedError( "Should have implemented this method." )
  
  def getFilename(self, fieldname):
  """
  Get upload filename based on the fieldname.
  Parameters:
   fieldname: string
  Return:
   string: filename
  """
  self.riseError()
  
  def getMimetype(self, fieldname):
  """
  Get upload file mime type based on the fieldname.
  Parameters:
   fieldname: string
  Return:
   string: mimetype
  """
  self.riseError()
  
  def saveFile(self, fieldname, fullNamePath):
  """
  Save the upload file based on the fieldname on the fullNamePath location.
  Parameters:
   fieldname: string
   fullNamePath: string
  """
  self.riseError()
  
  
  class FlaskAdapter(BaseAdapter):
  """
  Flask Adapter: Check BaseAdapter to see what methods description.
  """
  
  def checkFile(self, fieldname):
  if fieldname not in self.request.files:
   raise Exception("File does not exist.")
  
  def getFilename(self, fieldname):
  self.checkFile(fieldname)
  return self.request.files[fieldname].filename
  
  def getMimetype(self, fieldname):
  self.checkFile(fieldname)
  return self.request.files[fieldname].content_type
  
  def saveFile(self, fieldname, fullNamePath):
  self.checkFile(fieldname)
  file = self.request.files[fieldname]
  file.save(fullNamePath)
  

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