| | 1 | ============ |
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| | 2 | Form preview |
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| | 3 | ============ |
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| | 4 | |
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| | 5 | Django comes with an optional form preview application that helps with the |
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| | 6 | following workflow: |
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| | 7 | |
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| | 8 | "Display an HTML form, force a preview, then do something with the submission." |
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| | 9 | |
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| | 10 | To force a preview of a form submission, all you have to do is write a short |
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| | 11 | Python class. |
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| | 12 | |
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| | 13 | Overview |
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| | 14 | ========= |
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| | 15 | |
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| | 16 | Given a ``django.newforms.Form`` object that you define, this application takes |
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| | 17 | care of the following workflow: |
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| | 18 | |
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| | 19 | 1. Displays the form as HTML on a Web page. |
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| | 20 | 2. Validates the form data once it's submitted via POST. |
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| | 21 | a. If it's valid, displays a preview page. |
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| | 22 | b. If it's not valid, redisplays the form with error messages. |
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| | 23 | 3. At the preview page, if the preview confirmation button is pressed, calls |
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| | 24 | a hook that you define -- a done() method. |
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| | 25 | |
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| | 26 | The framework enforces the required preview by passing a shared-secret hash to |
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| | 27 | the preview page. If somebody tweaks the form parameters on the preview page, |
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| | 28 | the form submission will fail the hash comparison test. |
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| | 29 | |
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| | 30 | How to use FormPreview |
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| | 31 | ====================== |
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| | 32 | |
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| | 33 | 1. Point Django at the default FormPreview templates. There are two ways to |
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| | 34 | do this: |
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| | 35 | |
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| | 36 | * Add ``'django.contrib.formtools'`` to your ``INSTALLED_APPS`` |
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| | 37 | setting. This will work if your ``TEMPLATE_LOADERS`` setting includes |
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| | 38 | the ``app_directories`` template loader (which is the case by |
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| | 39 | default). See the `template loader docs`_ for more. |
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| | 40 | |
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| | 41 | * Otherwise, determine the full filesystem path to the |
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| | 42 | ``django/contrib/formtools/templates`` directory, and add that |
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| | 43 | directory to your ``TEMPLATE_DIRS`` setting. |
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| | 44 | |
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| | 45 | 2. Create a FormPreview subclass that overrides the done() method of the |
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| | 46 | FormPreview class:: |
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| | 47 | |
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| | 48 | from django.contrib.formtools import FormPreview |
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| | 49 | from myapp.models import SomeModel |
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| | 50 | |
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| | 51 | class SomeModelFormPreview(FormPreview): |
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| | 52 | |
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| | 53 | def done(self, request, cleaned_data): |
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| | 54 | ''' Submit form, then redirect to success ''' |
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| | 55 | return HttpResponseRedirect('/form/success') |
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| | 56 | |
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| | 57 | This method takes an HttpRequest object and a dictionary of the form |
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| | 58 | data after it has been validated and cleaned. It should return an |
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| | 59 | HttpResponseRedirect that is the end result of the form being submitted. |
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| | 60 | The FormPreview subclass can live anywhere in your codebase. |
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| | 61 | |
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| | 62 | 3. Change your URLconf to point to the ``FormPreview`` workflow:: |
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| | 63 | |
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| | 64 | from myapp.preview import SomeModelFormPreview |
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| | 65 | from myapp.models import SomeModel |
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| | 66 | from django import newforms as forms |
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| | 67 | |
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| | 68 | ...and add the following line to the appropriate model in your URLconf:: |
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| | 69 | |
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| | 70 | (r'^post/$', SomeModelFormPreview(forms.models.form_for_model(SomeModel))), |
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| | 71 | |
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| | 72 | or if you already have a Form class defined for the model:: |
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| | 73 | |
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| | 74 | (r'^post/$', SomeModelFormPreview(SomeModelForm)), |
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| | 75 | |
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| | 76 | 4. Run the Django server and visit the appropriate model ``/post/`` in |
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| | 77 | your browser. |
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| | 78 | |
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| | 79 | .. _template loader docs: ../templates_python/#loader-types |
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| | 80 | |
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| | 81 | FormPreview classes |
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| | 82 | =================== |
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| | 83 | |
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| | 84 | A FormPreview class is a simple Python class that represents the preview |
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| | 85 | workflow. FormPreview classes must subclass |
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| | 86 | ``django.contrib.formtools.preview.FormPreview`` and override the done() method. |
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| | 87 | They can live anywhere in your codebase. |
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| | 88 | |
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| | 89 | FormPreview templates |
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| | 90 | ===================== |
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| | 91 | |
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| | 92 | By default, the form is rendered via the template ``formtools/form.html``, and |
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| | 93 | the preview page is rendered via the template ``formtools.preview.html``. These |
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| | 94 | values can be overridden for a particular form preview by setting |
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| | 95 | ``preview_template`` and ``form_template`` attributes on the FormPreview |
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| | 96 | subclass. See ``django/contrib/formtools/templates`` for the default templates. |