This weekend I was relatively rainy forced to stay at home and not having to do a beep ... sn I made a little hack I have already spoken with Python.Ne python, but most other times I look at it is more like me .. It 's great! Simple, fast, object-oriented (in Python everything is an object ...), but also has data structures that allow you to manipulate their contents with few lines of code (except one) unlike other languages \u200b\u200bthat it takes tens of lines ... I'm talking about structures such as dictionaries, tuples, lists and collections ... Documentatevi a bit ... Anyway the purpose of my post is to show you how to use python for web frameworks like without Zope, Django, WebWare .. But only volumes python, mysql and much loved, robust and secure Apache web server that has contributed heavily to the growth of the World Wide Web. And we'll see how easy it is to implement the MVC (Model View Controller) with this solution.
Here's what we need on the pc:
sudo apt-get install apache2 libapache2-mod-python, mysql-server , python-MySQLdb
I did not put in the command python usually already installed if not add it .. Obviously I'm assuming you have Ubuntu or a Debian derivative. Winblows if you go to Google to see how to install .. then I suggest you use the python plugin for eclipse PyDev that has code completion ee all other future profits (.. even if it lacks support for PSP, I'm not talking about playstation will explain later ... but I solved my building a plugin;)) Anyway here is the structure of the final project so there you an idea of \u200b\u200bwhere to place the file is if you use both eclipse and if you work directly in the directory with a text editor:
this course is the structure that I chose, but no one undertakes to respect it ... As you have guessed from the image put on a simple guestbook ... In the src folder there are the sources and everything will fall into the server folder Apache.Nella I put a backup folder resource to give directives to the apache configuration and the sql to generate the table on db.Il Ant build.xml file that you see I do not always created for a server to the user cp and launch the eclipse we do not use it all for our purposes (the Eclipse project ... but you can download from the link I give at the bottom of the post). In the src folder structure we have a package that contains the Python source code related to the model ( dto, dao etc.. you see that I have a strong influence Java ...) then index.py a file that acts as a controller and the pages in the folder psp PSP (Python Server Page) that form the view .... The PSP python are nothing more than a port (very limited) that are JSP to JAVA. That mix Python code in HTML in order to decide the logic of that rendering, but you will understand better read on (m or the big shot and some java guru is about to beat me, but mind you are my introductory tutorial for those who are beginners like I was and I'm not going to go down in the technical). To better understand what we're going to build and how the various components work together memorizzatevi the following scheme:
diagram is represented as a logical scheme of the CompoNet interact with each other after a http request from a client. On the right side of the diagram shows the directory where we will put our web project once complete or at least to test it with subdirectories and files. Try to explain the flow:
sudo mysql-u-p
DEVELOPMENT APPLICATION begin with the model that the data be treated. How did you know the creation of the table we have only one type of data that we create and then spends the 'python object that represents our information here is the code:
piergiuseppe82.guestbook.model Enter the code in the package. Each instance of this object will be used as a data transport object (DTO) between DedicaDao.py and index.py. Without this we will create the service object that will handle data access (DAO) on the db and then in the package insert piergiuseppe82.guestbook.model.dao DedicaDao.py:
- Apache2 Web Server MySql server
- the apache module
- mod_python for python library python MySQLdb
- nn and of course if the Python interpreter installed on your system
sudo apt-get install apache2 libapache2-mod-python, mysql-server , python-MySQLdb
I did not put in the command python usually already installed if not add it .. Obviously I'm assuming you have Ubuntu or a Debian derivative. Winblows if you go to Google to see how to install .. then I suggest you use the python plugin for eclipse PyDev that has code completion ee all other future profits (.. even if it lacks support for PSP, I'm not talking about playstation will explain later ... but I solved my building a plugin;)) Anyway here is the structure of the final project so there you an idea of \u200b\u200bwhere to place the file is if you use both eclipse and if you work directly in the directory with a text editor:
this course is the structure that I chose, but no one undertakes to respect it ... As you have guessed from the image put on a simple guestbook ... In the src folder there are the sources and everything will fall into the server folder Apache.Nella I put a backup folder resource to give directives to the apache configuration and the sql to generate the table on db.Il Ant build.xml file that you see I do not always created for a server to the user cp and launch the eclipse we do not use it all for our purposes (the Eclipse project ... but you can download from the link I give at the bottom of the post). In the src folder structure we have a package that contains the Python source code related to the model ( dto, dao etc.. you see that I have a strong influence Java ...) then index.py a file that acts as a controller and the pages in the folder psp PSP (Python Server Page) that form the view .... The PSP python are nothing more than a port (very limited) that are JSP to JAVA. That mix Python code in HTML in order to decide the logic of that rendering, but you will understand better read on (m or the big shot and some java guru is about to beat me, but mind you are my introductory tutorial for those who are beginners like I was and I'm not going to go down in the technical). To better understand what we're going to build and how the various components work together memorizzatevi the following scheme: 
diagram is represented as a logical scheme of the CompoNet interact with each other after a http request from a client. On the right side of the diagram shows the directory where we will put our web project once complete or at least to test it with subdirectories and files. Try to explain the flow:
- The client (the web broweser) requires the resource to the server index.py
- the Apache server takes consider the request and because he was told that all requests for extension of the site. py must be eleaborate from mod_python passes the ball to him.
- The python module then calls the resource index.py
- Index.py decide, based on function, they need access to the model to save or read one or more belongings Dedica.py then called DedicaDao.py
- DedicaDao. py using the MySQLdb python module (which I forgot sn shown) accesses the MySQL db and writes or reads data returning the result to index.py
- Once processed the data, all at the mod_python Index.py returns saying that PSP developing and passing the necessary data
- The mod_python PSP processes the generated html to be returned to the Apache server Apache
- html returns received in response to the client
- The client receiving the response with the HTML it renders in the finastra broweser.
Configuring Apache for saying that the project must use the mod_python and what resources will not make pubbliche.Quindi open with text editor the file: gedit / etc/apache2/sites-available / default and add the following lines:
As you can see are three directives directory: First Directive:
As you can see are three directives directory: First Directive:
- PYTHONPATH: where they are used to define the python modules (the *. py of our model) to use as a library to load the mod_python.
- AddHandler: we said that the requests sent to PyGuestbook with. Py be the module to deal
- PythonHandler python: python module to tell the handler to use the "publisher" (if you read the official documentation and understand better what that there are others)
- PythonDebug We will put it to ON to tell the module that we are being development and present the error in the browser. In production is set to OFF in order to get the classic error 500 (Internal server error) in case of problems.
- say to apache qualsia must decline the request to the directory containing the libraries
- say to apache qualsia must decline the request to the folder containing your psp
PREPARATION MYSQL
Now let us create a MySql db and table. Log in to mysql:
enter your password and you provide the command-line mysql.
Create db with the command: create database
test_py;
move created in the database:
use test_py;
create the table we need:
DEVELOPMENT APPLICATION begin with the model that the data be treated. How did you know the creation of the table we have only one type of data that we create and then spends the 'python object that represents our information here is the code:
piergiuseppe82.guestbook.model Enter the code in the package. Each instance of this object will be used as a data transport object (DTO) between DedicaDao.py and index.py. Without this we will create the service object that will handle data access (DAO) on the db and then in the package insert piergiuseppe82.guestbook.model.dao DedicaDao.py:
As you can see the service object contains a method definition for each CRUD (Create Read Update Delete) we are going to do on the db, plus two private methods that are used to convert the records taken from the db in instances of objects Dedication.
be noted how python MySQLdb module is used for communicating with the MySQL server and other services for communicating with the latter. (Do not explain every line of code because it is not the purpose of the tutorial, if you are unsure what makes a particular line of code go to the official documentation of python.)
Now, we are actively linked to the Web application that is decides that the application must meet the following user requirements:
1.Insert a nickname to be saved in the dedication and maintain the authenticated user.
2.Insert and save on a new dedicated db where the user is already present prepolare the field with the nickname entered otherwise give an error message.
3.Visualuzzare the list of dedications, with access to the modification of any dedication and its possible elimination.
4.Editare a dedication and save it to db.
5.Eliminare dedication.
qnd bed now transformed by the requirements in web services in python code. So here below our index.py to put in the src folder:
As I mentioned above is the code from the controller and he will always be out an inquiry to respond to the browser (of course after the request has passed and made readable by apache mod_python). So understand how this works and makes you understand how to use everything and customize as you wish.
Now I have to explain how the communication between the mod_python index.py out our form.
First of all we talk about the urls that identify our services.
To invoke a service to our form we must enter into your browser:
http://localhost/PyGuestbook/index.py
where PyGuestbook is the folder to which puta apache / var / www / PyGuestbook containing our application which is also in the context of request. index.py is the form that we provided. In calls like that in the end only with the mod_python module, the default is to call the method defined in the module index index.py. If not defined returns a 404.
I say default because we have the possibility to specify the service.
For example if we want the new service dedicated to just call from the browser:
http://localhost/PyGuestbook/index.py/nuova_dedica
For every call to a method our controller to pass as a parameter the mod_python request (in the code if you see each method has a parameter which stands for Request req).
Doppo doing what is expected in response to the mod_python method is a string, which contains the code to generate html. In our case, however, we can do to generate mod_python same with the PSP (Python Server Pages), referring to his service.
comment code.
First we import the necessary modules like mod_python python modules and our model.
Then we have a number of private constants to the module that contains index.py strings used in code.
Going there is the configuraione dell'oggeto used for logging.
Finally, all methods invoked as services in the url of the request form index.py.
Let me explain in general what are the methods and as a requirement to be met. After I will explain in more detail, the better you understand how your code to comply with the requirement 2.
def index (req):
ago as an entry point to the module home page and in our case. It goes to meet the requirement that no one save in session dell'nickname used as access to the guestbook.
final nuova_dedica (req):
is invoked to access the service by inserting a new dedication and prepares necessary for the correct Displayed the psp response. Go to fulfill the requirement 2.
final salva_dedica (req, nickname, email, dedication):
is invoked in the form of post insertion of a new dedication which calls the DAO for the persistence of the latter. Then prepare the necessary for the rendering of the psp response. Go to fulfill the requirement 2.
final nuovo_nick (req):
this service is invoked from a link on the home page and takes care to clean the session of the previously inserted by nick index. It is part of a requirement
final lista_dediche (req):
deals call the dao to get all the dedications to save and advance psp as a parameter that takes care to see it. Go to fulfill requirement 3.
final elimina_dedica (req, id):
is responsible to call the dao to erase the inscription which has the id passed in the request. Go to fulfill the requirement 3 Pate, and meets the requirement 5.
final edit_dedica (req, id):
goes to prepare the necessary for the display of the inscription which has the id passed in the request by invoking the dao for this instance and then move on to the psp that deals with renderziarla in the edit form of a dedication. He goes to meet part of the requirements 3 and 4.
final aggiorna_dedica (req, id, nickname, email, dedication):
this service is called in after the edit form of a dedication by the dao and goes to update the dedication on db. Satisfies the requirement 4.
Now compredere how to better implement the code to process all components together so spiegherù dettaglioto a single use case. The inclusion of a new dedication.
The browser client side requires the insertion of a new service through a dedicated link on the homepage that points to the URL:
http://localhost/PyGuestbook/index.py/nuova_dedica
mod_python the answers because we want a *. py and specifically the form index.py occorge then we specified a service module that index.py nuova_dedica then goes to call the method with the same name as a parameter through the request.
Respond new method dedication:
What?
- - logs the first entry to the method
- -
- recalls the session - is to set the defaul type of response, in this case text / html
- after you go to prepare a template or a psp to develop the mod_python in our case the psp to show the form for entering the new dedication.
- - Then prepare two variables will contain messages and any messages will contain the nickname nickname.
- - Try to recall the user's nickname in the session made by index method and the sect in the variable.
- - If you change your nickname is blank psp develop and prepare the message to be Displayed error message to the psp.
- - So says all'oggeto psp to process the template, passing it a dictionary containing the variables needed.
We see the subcase where the nickname is blank, we said that the process goes to psp messages.psp message here is how it is made:
first we have a Directive psp psp inclusion of another in our case the Hedera. psp (containing the top generated html; bottom of the post will give you the psp). So for a psp uncludere Directive is:
\u0026lt;% @ include file = "nomedelfile.psp"%>
after the include directive, we have a scriptlet, or part of python code. It is enclosed in tags
\u0026lt;% .. %>
The code in question is to test the variable from the method nickname passatagli nuova_dedica index.py module. If this is not empty renders the contents of the variable preceded by the text Hello and followed by the new tag line, in short, the html to render the if statement if the condition is met. So to render the contents of a variable using the directive
\u0026lt;% = varname%>.
After you open and close the python code \u0026lt;%%> which may seem empty, but it is not. In reality there is the closure of the intent of the construct if (if you follow this tutorial then you have some experience in python and you understand what I'm talking about). In fact, no such termination or messages would be displayed if nickname is empty.
Hence, the Directive of the message passed to see them always as a parameter.
In the end there is another include directive, but in this case, the footer contains the bottom of the html code.
Now we move to another nickname in case that the variable is retrieved by the method Sesion nuova_dedica. In this case we have to draw the psp newDedica.psp said, here's how it is done:
contains besides as you see in the html header and footer for a form that allows you to enter the Username, Email and message of Dedication. The nickname is as you see prevalorizzato python with the directive to render the nickname of the variable passed as the run method of the object paramet psp mod_python.
Also note that where the form is posted
/ PyGuestbook / index.py / salva_dedica
Let's go with, let's say you fill up the form in the browser and press the Save dedication.
The post contained in the request comes to the method of the form salva_dedica index.py:
the method gets the request and notice in this case paramtri the method that in addition to the request also contains the names data to form fields. Indeed in this mod_python paremetri have entered the correct values \u200b\u200bwithout the need for us to go and retrieve dall'oggeto req.
makes the usual preparations to pass variables and PSQ to render. Then validate the data and if they do not comply with the condition to be exploited to change the psp to be rendered with that of prior view and enhances the value of the variable messages.
Otherwise it points to the Dao to the inclusion of the new dedication.
Once inserted, again via the dao, goes to retrieve the list of dedications to put them in variebile dedications to pass to the template.
Well let's say it went well then the psp tt processable listaDediche.psp:
liquids in the psp check first if the object is not empty lista_dediche dedication in case of success begins to render the table with the column names to the list and then loops for each devotes to see them go to insertion date, nickname, email and message. The last column is to add the link to the change and the elimination of the dedication passing as a parameter in the request id of the inscription in question.
Well I'm done and I hope that the explanation of this use case I have clarified the operation of all or how to use python for the web in its simplest form + observing the MVC pattern.
To test that there is copy the contents of folder src into / var / www / PyGuestbook
Maybe you can measure in solving some bugs that we are in If the user fails to comply with the navigation flow ..
Here are the contents of the PSP is not treated so far:
