Re: GET and POST in forms. Please help me understand the logic!

[Andrew Taylor]

Awesome I feel much better about this now. Thanks for your help!

On Thursday, 28 November 2013 09:29:05 UTC, Daniel Roseman wrote:
>
> On Thursday, 28 November 2013 03:24:11 UTC, Andrew Taylor wrote:
>>
>> Hi,
>>
>> I'm struggling with the concepts of get and post and where these status 
>> come from in the workflow. I have worked my way through the official pages 
>> on forms but I have not quite understood this to my satisfaction.
>>
>> I get the gist that:
>>
>>- get is for requesting data and 
>>- the query string parameters are visible 
>>- Running multiple get operations with say a bookmarked link has no 
>>negative effect
>>
>> whereas with post
>>
>>- post is for making database changes
>>
>> Beyond this I am a little clueless.
>>
>>- When does a request method get assigned? 
>>- In other words, with this code below, what would have made the 
>>request method become post (or get)? Is this related to a preceding view?
>>- Does a request object have to have a get or a post dictionary in 
>>it? Could it have neither?
>>- Does a request object going to a form have to have a get or a post 
>>dictionary in it?
>>- Is it the case that with "add_category.html" the page could open 
>>with neither a get or post in the request, and while the "add_category" 
>>view is running the request method POST could be assigned?
>>- Does a POST method invoke form validation?
>>
>>
>> Example:
>>
>> def add_category(request, category_name_url=""):
>> context = RequestContext(request)
>>
>> if request.method == 'POST':
>> form = CategoryForm(request.POST)
>>
>> if form.is_valid():
>> form.save(commit=True)
>> return index(request)
>> else:
>> print form.errors
>>
>> else:
>> form = CategoryForm
>>
>>
>> return render_to_response('rango/add_category.html', {'form': form}, 
>> context)
>>
>>
>> Thanks,
>>
>>
>> Andy
>>
>>
>>
> This isn't really anything to do with Django, but the general semantics of 
> the web.
>
> *All* requests have a verb associated with them, and most of the time that 
> verb is GET: basically, your browser is requesting that the server give 
> them a page from the given address. That address might include a 
> querystring, which servers parse into GET parameters, or it might not. 
> Again, the generally accepted use of the querystring is that it in some way 
> affects the document that is returned - for example, requesting a specific 
> page in a paginated set - rather than modifying something on the server 
> itself.
>
> When you want to send information from your browser to the server, you 
> would mostly use POST. Most of the time, that is done by sending a form. 
> But note that it is the HTML that determines this: your form tag has an 
> `method` parameter, which is either GET or POST,  and when you click submit 
> the information is sent with the specified method to the URL given in the 
> `action` parameter:
> 
> Again, note that it is perfectly valid to use GET here, for example in a 
> form that specifies values to be used in a search - because you're 
> affecting what is returned to you, but not changing anything on the server. 
> But a registration form, or a form where you enter your CMS content for 
> posting, would always be POST.
>
> Now in Django, we have settled on a particular pattern, which works like 
> this:
> * Browser requests the page, ie GET.
> * Server returns the form to be filled in (possibly pre-populated with 
> data).
> * Form is sent back via POST to the *same URL*.
> * In the view, execution enters the `if request.method=="POST"` block and 
> therefore invokes form validation.
> * Server either returns invalid form (with errors) or saves the content 
> and redirects (via GET) to another URL.
>
> (Not to confuse you, but HTTP supports other verbs too, including PUT and 
> DELETE, but these are used mainly in REST and can't usually be generated by 
> browsers.)
>
> Hope this helps.
> --
> DR.
>

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Re: GET and POST in forms. Please help me understand the logic!

[Petr Přikryl]

Have a look at the book RESTful Web Services, page 5 (Chapter 1) and on.
http://it-ebooks.info/book/391/
 
You can read it on-line http://it-ebooks.info/read/391/ -- physical page 26/440,
section "HTTP: Documents in Envelopes".
 
Have a nice day,
   P.
__

Od: Andrew Taylor 
Komu: 
Datum: 28.11.2013 04:24
Předmět: GET and POST in forms. Please help me understand the logic!


Hi,I'm struggling with the concepts of get and post and where these status come from in the 
workflow. I have worked my way through the official pages on forms but I have not quite understood 
this to my satisfaction.I get the gist that:get is for requesting data and the query string 
parameters are visible Running multiple get operations with say a bookmarked link has no negative 
effectwhereas with postpost is for making database changesBeyond this I am a little clueless.When 
does a request method get assigned? In other words, with this code below, what would have made the 
request method become post (or get)? Is this related to a preceding view?Does a request object have 
to have a get or a post dictionary in it? Could it have neither?Does a request object going to a 
form have to have a get or a post dictionary in it?Is it the case that with 
"add_category.html" the page could open with neither a get or post in the request, and 
while the "add_category" view is running the re
quest method POST could be assigned?Does a POST method invoke form validation?Example:def 
add_category(request, category_name_url=""):    context = 
RequestContext(request)    if request.method == 'POST':        form = 
CategoryForm(request.POST)        if form.is_valid():            form.save(commit=True)   
         return index(request)        else:            print form.errors    else:        
form = CategoryForm    return render_to_response('rango/add_category.html', {'form': 
form}, context)Thanks,Andy 
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Re: GET and POST in forms. Please help me understand the logic!

[Daniel Roseman]

On Thursday, 28 November 2013 03:24:11 UTC, Andrew Taylor wrote:
>
> Hi,
>
> I'm struggling with the concepts of get and post and where these status 
> come from in the workflow. I have worked my way through the official pages 
> on forms but I have not quite understood this to my satisfaction.
>
> I get the gist that:
>
>- get is for requesting data and 
>- the query string parameters are visible 
>- Running multiple get operations with say a bookmarked link has no 
>negative effect
>
> whereas with post
>
>- post is for making database changes
>
> Beyond this I am a little clueless.
>
>- When does a request method get assigned? 
>- In other words, with this code below, what would have made the 
>request method become post (or get)? Is this related to a preceding view?
>- Does a request object have to have a get or a post dictionary in it? 
>Could it have neither?
>- Does a request object going to a form have to have a get or a post 
>dictionary in it?
>- Is it the case that with "add_category.html" the page could open 
>with neither a get or post in the request, and while the "add_category" 
>view is running the request method POST could be assigned?
>- Does a POST method invoke form validation?
>
>
> Example:
>
> def add_category(request, category_name_url=""):
> context = RequestContext(request)
>
> if request.method == 'POST':
> form = CategoryForm(request.POST)
>
> if form.is_valid():
> form.save(commit=True)
> return index(request)
> else:
> print form.errors
>
> else:
> form = CategoryForm
>
>
> return render_to_response('rango/add_category.html', {'form': form}, 
> context)
>
>
> Thanks,
>
>
> Andy
>
>
>
This isn't really anything to do with Django, but the general semantics of 
the web.

*All* requests have a verb associated with them, and most of the time that 
verb is GET: basically, your browser is requesting that the server give 
them a page from the given address. That address might include a 
querystring, which servers parse into GET parameters, or it might not. 
Again, the generally accepted use of the querystring is that it in some way 
affects the document that is returned - for example, requesting a specific 
page in a paginated set - rather than modifying something on the server 
itself.

When you want to send information from your browser to the server, you 
would mostly use POST. Most of the time, that is done by sending a form. 
But note that it is the HTML that determines this: your form tag has an 
`method` parameter, which is either GET or POST,  and when you click submit 
the information is sent with the specified method to the URL given in the 
`action` parameter:

Again, note that it is perfectly valid to use GET here, for example in a 
form that specifies values to be used in a search - because you're 
affecting what is returned to you, but not changing anything on the server. 
But a registration form, or a form where you enter your CMS content for 
posting, would always be POST.

Now in Django, we have settled on a particular pattern, which works like 
this:
* Browser requests the page, ie GET.
* Server returns the form to be filled in (possibly pre-populated with 
data).
* Form is sent back via POST to the *same URL*.
* In the view, execution enters the `if request.method=="POST"` block and 
therefore invokes form validation.
* Server either returns invalid form (with errors) or saves the content and 
redirects (via GET) to another URL.

(Not to confuse you, but HTTP supports other verbs too, including PUT and 
DELETE, but these are used mainly in REST and can't usually be generated by 
browsers.)

Hope this helps.
--
DR.

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Re: GET and POST in forms. Please help me understand the logic!

[Thomas]

I understand the confusion. Part of it is probably that GET and POST, is not 
part of Django per se, but part of the HTTP standard. 

Also confusing is that Django, especially in that code you pasted below, a lot 
is abstracted away. 

Sorry for the lack of detail, typing from iMe, just wanted to knock out a 
response. 



> On Nov 27, 2013, at 10:24 PM, Andrew Taylor  wrote:
> 
> Hi,
> 
> I'm struggling with the concepts of get and post and where these status come 
> from in the workflow. I have worked my way through the official pages on 
> forms but I have not quite understood this to my satisfaction.
> 
> I get the gist that:
> get is for requesting data and 
> the query string parameters are visible 
> Running multiple get operations with say a bookmarked link has no negative 
> effect
> whereas with post
> post is for making database changes
> Beyond this I am a little clueless.
> When does a request method get assigned? 
> In other words, with this code below, what would have made the request method 
> become post (or get)? Is this related to a preceding view?
> Does a request object have to have a get or a post dictionary in it? Could it 
> have neither?
> Does a request object going to a form have to have a get or a post dictionary 
> in it?
> Is it the case that with "add_category.html" the page could open with neither 
> a get or post in the request, and while the "add_category" view is running 
> the request method POST could be assigned?
> Does a POST method invoke form validation?
> 
> Example:
> 
> def add_category(request, category_name_url=""):
> context = RequestContext(request)
> 
> if request.method == 'POST':
> form = CategoryForm(request.POST)
> 
> if form.is_valid():
> form.save(commit=True)
> return index(request)
> else:
> print form.errors
> 
> else:
> form = CategoryForm
> 
> 
> return render_to_response('rango/add_category.html', {'form': form}, 
> context)
> 
> 
> Thanks,
> 
> 
> Andy
> 
> 
> 
> 
> 
> -- 
> You received this message because you are subscribed to the Google Groups 
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> To unsubscribe from this group and stop receiving emails from it, send an 
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> Visit this group at http://groups.google.com/group/django-users.
> To view this discussion on the web visit 
> https://groups.google.com/d/msgid/django-users/6367ae1d-fc71-4137-9140-3573a8a5dedc%40googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.

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GET and POST in forms. Please help me understand the logic!

[Andrew Taylor]

Hi,

I'm struggling with the concepts of get and post and where these status 
come from in the workflow. I have worked my way through the official pages 
on forms but I have not quite understood this to my satisfaction.

I get the gist that:

   - get is for requesting data and 
   - the query string parameters are visible 
   - Running multiple get operations with say a bookmarked link has no 
   negative effect

whereas with post

   - post is for making database changes

Beyond this I am a little clueless.

   - When does a request method get assigned? 
   - In other words, with this code below, what would have made the request 
   method become post (or get)? Is this related to a preceding view?
   - Does a request object have to have a get or a post dictionary in it? 
   Could it have neither?
   - Does a request object going to a form have to have a get or a post 
   dictionary in it?
   - Is it the case that with "add_category.html" the page could open with 
   neither a get or post in the request, and while the "add_category" view is 
   running the request method POST could be assigned?
   - Does a POST method invoke form validation?


Example:

def add_category(request, category_name_url=""):
context = RequestContext(request)

if request.method == 'POST':
form = CategoryForm(request.POST)

if form.is_valid():
form.save(commit=True)
return index(request)
else:
print form.errors

else:
form = CategoryForm


return render_to_response('rango/add_category.html', {'form': form}, 
context)


Thanks,


Andy





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