Python template cgi

Learn more. Asked 7 years, 8 months ago. Active 7 years, 8 months ago. Viewed 1k times. Add a comment. Active Oldest Votes. Dan Hogan Dan Hogan 1, 1 1 gold badge 16 16 silver badges 16 16 bronze badges. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. When you have tested that your web form has all the right names and initial values, you can change the action URL to your CGI script name like quotient. Make sure your local server is still running!

To allow easy concentration on the data sent by the browser, this form connects to a simple CGI script dumpcgi. Press the submit button in the form, and see the result. Back up from the output to the previous page, the form, and change some of the data in all kinds of fields.

Submit again and see the results. Play with this until you get the idea clearly that the form is passing on your data. If you want to create a form and input fields using the Kompozer GUI , open this same file, the www example commonFormFields.

The static text in this page is set up as a tutorial on forms in Kompozer. Read the content of the page describing how to edit at least forms with text input fields and submit buttons. The other fancier fields are optional — not needed for the chapter exercises. Read the static text about how to edit individual fields, and change some field parameters, save the file and reload it in your browser, and submit again.

If you change the name or value attributes, they are immediately indicated in the dumped output. If you change things like the text field size, it makes a change in the way the form looks and behaves. You can return to the original version: An extra copy is saved in commonFormFieldsOrig. Now we have discussed the last piece, web forms, in the diagram for the comparison of generating web pages dynamically by a regular Python program or a server CGI script:. Note the last three Python videos do not directly corresponding to a single place in the Tutorial text.

Instead they go through the entire process for web based programs from the beginning. Video 4. In the middle video 4. Remember that you must have the local server running first. You must have all the associated files in the same directory as the server program you are running, and you cannot just click on quotient. The simplest would be to just add three numbers instead of two. Call your form dynamic.

Call your CGI script dynamic. Call an output template dynamicTemplate. Remember the details listed in the previous exercise to make the results work on localhost. Summary starts with the overall process for creating dynamic web pages. One of the advantages of having a program running on a public server is that data may be stored centrally and augmented and shared by all.

In high performance sites data is typically stored in a sophisticated database, beyond the scope of this tutorial. For a less robust but simpler way to store data persistently, we can use simple text files on the server. The www example page namelist. You can test the program with your local Python server.

It is less impressive when you are the only one who can make changes! The source code is documented for those who would like to have a look. You also may want to look at the source code of the utility script you have been using, dumpcgi. It uses a method of getting values from the CGI data that has not been discussed:. This method returns a list of values associated with a name from the web form.

The list many have, 0, 1, or many elements. It is needed if you have a number of check boxes with the same name. Maybe you want a list of all the toppings someone selects for a pizza. Both dumpcgi. The function safePlainText replaces reserved symbols with appropriate alternatives. The examples in earlier sections were designed to illustrate the flow of data from input form to output page, but neither the html or the data transformations have been very complicated.

A more elaborate situation is ordering pizza online, and recording the orders for the restaurant owner. To see the report, the owner needs to know the special name owner After ordering several pizzas, enter that name and press the Submit button again. This CGI script gets used in two ways by a regular user: initially, when there is no order, and later to confirm an order that has been submitted.

The two situations use different logic, and the script must distinguish what is the current use. A hidden variable is used to distinguish the two cases: when pizza1. On the other hand the pizzaOrderTemplate1. The CGI script checks the value of the field pastState , and varies its behavior based on whether the value is 'order' or not. The form in pizzaOrderTemplate1.

Keeping multiple active copies of data is not a good idea: They can get out of sync. If you look at the source code for pizzaOrderTemplate1. In the better version with altered files pizza. To do the dynamic generation, templates for an individual html line with a size radio button is in the source code, and it is used repeatedly to generate multiple lines, each with a different size and price embedded into the format string from the program data.

These lines are joined together and placed as one entity into the html form template. A similar procedure is done with the toppings and check-boxes. A further possible elaboration would be to also allow the restaurant manager to edit the size, cost and available topping data online, and store the data in a file rather than having the data hard coded in pizza.

This change would be a fairly elaborate project compared to the earlier exercises! Composing Web Pages in Python. Enter search terms or a module, class or function name. Navigation index next previous Hands-on Python Tutorial » 4.

Dynamic Web Pages ». You cannot run a. Windows In an operating system file window, go to the folder with the www examples. Double click on startServer. Mac This is more involved the first time. See Some Special Mac Instructions.

Warning Do not start the local server running from inside Idle. Note If the server aborts and gives an error message about spaces in the path , look at the path through the parent directories over this www directory. If the form contains non-ASCII characters, use the encoding keyword parameter set to the value of the encoding defined for the document.

This reads the form contents from the standard input or the environment depending on the value of various environment variables set according to the CGI standard. Since it may consume standard input, it should be instantiated only once.

The FieldStorage instance can be indexed like a Python dictionary. It allows membership testing with the in operator, and also supports the standard dictionary method keys and the built-in function len.

For instance, the following code which assumes that the Content-Type header and blank line have already been printed checks that the fields name and addr are both set to a non-empty string:. Here the fields, accessed through form[key] , are themselves instances of FieldStorage or MiniFieldStorage , depending on the form encoding. The value attribute of the instance yields the string value of the field.

The getvalue method returns this string value directly; it also accepts an optional second argument as a default to return if the requested key is not present. If the submitted form data contains more than one field with the same name, the object retrieved by form[key] is not a FieldStorage or MiniFieldStorage instance but a list of such instances.

Similarly, in this situation, form. If you expect this possibility when your HTML form contains multiple fields with the same name , use the getlist method, which always returns a list of values so that you do not need to special-case the single item case.

For example, this code concatenates any number of username fields, separated by commas:. If a field represents an uploaded file, accessing the value via the value attribute or the getvalue method reads the entire file in memory as bytes. This may not be what you want. You can test for an uploaded file by testing either the filename attribute or the file attribute.

You can then read the data from the file attribute before it is automatically closed as part of the garbage collection of the FieldStorage instance the read and readline methods will return bytes :. FieldStorage objects also support being used in a with statement, which will automatically close them when done.

If an error is encountered when obtaining the contents of an uploaded file for example, when the user interrupts the form submission by clicking on a Back or Cancel button the done attribute of the object for the field will be set to the value When this occurs, the item will be a dictionary-like FieldStorage item. In this case, it can be iterated over recursively just like the top-level form object. In this case, the list , file , and filename attributes are always None.

Changed in version 3. This section describes a higher level interface which was added to this class to allow one to do it in a more readable and intuitive way. The interface consists of two simple methods. Using the methods you can process form data in a generic way, without the need to worry whether only one or more values were posted under one name.

In the previous section, you learned to write following code anytime you expected a user to post more than one value under one name:. This situation is common for example when a form contains a group of multiple checkboxes with the same name:. So you write a script containing for example this code:.

The problem with the code is that you should never expect that a client will provide valid input to your scripts. Calling the upper method on a list is not valid since lists do not have a method of this name and results in an AttributeError exception. Therefore, the appropriate way to read form data values was to always use the code which checks whether the obtained value is a single value or a list of values.