Lets say I have 2 radio buttons in my html script, of which one is checked by default:
<form action="" method="post">
<div class="radio-option checked">
<input type="radio" name="radioName" value="val_1"/>
</div>
<div class="radio-option">
<input type="radio" name="radioName" value="val_2"/>
</div>
<div>
<input type="submit" value="Confirm and continue"/>
</div>
</form>
If I click the submit button without clicking the other radio button, I get an error:
Bad Request The browser (or proxy) sent a request that this server
could not understand.
This happens because there is no value which is being transfered if a radio button is checked by default but not being selected with the mouse afterwards! This is what request.form shows me ImmutableMultiDict([]). If I select the other radio button with the mouse and click the submit button it shows me values ImmutableMultiDict(['radioName', 'val_2'])
I tried to catch the error like this, but it didn't work out:
if request.form == '':
flash('error')
return render_template('default_template.html')
How can I handle this within flask?
How can I set a default value, which can be sent to the server?
You could perform a check within flask. Check if request.form has items or if its empty and throw the error in that case.
A simple way of knowing if its empty would be, for example:
if len(request.form) == 0:
print('Error: The form is empty')
else:
print('The form has data, we can proceed')
Another way is:
if 'radioName' not in request.form:
print('Error: The form is empty')
...
But maybe flask has a better way of doing this or there are better practices to follow in these cases.
On the other hand, in the html snippet that you posted, none of the inputs is checked by default.
You have the checked css class on a div but not the checked attribute in an input with type=radio.
The correct use of checked attribute would be as follows:
<form action="" method="post">
<div class="radio-option checked">
<input type="radio" name="radioName" value="val_1" checked/>
</div>
<div class="radio-option">
<input type="radio" name="radioName" value="val_2"/>
</div>
<div>
<input type="submit" value="Confirm and continue"/>
</div>
</form>
This way, the radio input with value val_1, will be checked by default, populating the dictionary that goes to the server.
For more information, check out: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input/radio
You can also avoid sending empty forms to the server using the required attribute to make sure that the user fills the form as expected.
To learn more about this: https://developer.mozilla.org/en-US/docs/Learn/HTML/Forms/Form_validation
I hope it helps!
Related
<form action="/" method="post">
<button class="btn btn-outline-primary btn-sm" type="submit" name="submit_btn" value="favorites" data-
value="{{[i]}}">Favorites</button>
</form>
I have this button in Html, I want to obtain the variable "i" which is contained in the "data-value", to use it in Python, I'm using Flask also, thanks!.
The server (Flask/Python) won't have access to the data-value attribute when you submit the form. It's not part of the data that gets sent to the server.
You might try adding a "hidden" form element, which will send a key/value pair to the server without displaying anything to the user:
<form action="/" method="post">
<input type="hidden" name="value" value="{{[i]}}">
<button class="btn btn-outline-primary btn-sm" type="submit" name="submit_btn" value="favorites" data-value="{{[i]}}">Favorites</button>
</form>
As you can see, you can retain the data-value attribute on the button, but it's not doing anything so only keep it if you're using it in Javascript somehow.
Also note that {{[i]}} will output the string representation of an array with one value, i. So the value you will get on the server is "[5]" if i is 5 for instance. If you want an actual array on the server, there are other ways to do that.
I have a form that accepts image uploads:
<form name="upload" enctype="multipart/form-data" method="post" class="form-horizontal">
<div class="control-group">
<div class="span2">
<label for="image" class="control-label">Upload image:</label>
</div>
<div class="span10">
<input id="image" name="image" type="file" class="span7" accept="image/*"/>
</div>
</div>
<div class="form-group">
<div class="span2"></div>
<div class="span10">
<button class="btn btn-medium btn-primary" type="submit">Submit</button>
</div>
</div>
</form>
When I request.vars['image'], the following is returned:
FieldStorage('image', 'a.png', '\x89PNG\r\n\x1a\n\x00...')
How do I access these items? If I attempt to work with it as I would a dict, I receive an error that the object is not indexable. I've never worked with FieldStorage before, so I'm not exactly sure what I need to do to access this data.
If anyone else is interested, this worked:
request.vars['image'].filename
request.vars['image'].value
For the file name and binary data, respectively. Just needed a quick summary of the available attributes: http://python.about.com/od/cgiformswithpython/ss/pycgitut1_3.htm
This is extremely helpful if you are trying to check some aspects of a file before trying to process a form. I wanted to get the sha256 hash of an uploaded file and make sure it hadn't been uploaded before. The upload is in a field Field('file', 'upload').
Originally, I used the following, but this consumes the data in request.vars.file so that, after successful processing, the file written to disk is empty.
file_contents = request.vars.file.read()
form.vars.file_hash = hashlib.sha256(file_contents).hexdigest()
form.vars.file_length = len(file_contents)
However, in the updated code below datasci's answer allows you to access the data without consuming it from request.vars.file. Might be obvious, but it took a long time for me to figure out what was going on!
# Is there a file - the value will be None when the page first loads and
# can be 'str' if submit is pressed without a file selected.
if request.vars.file != None and not isinstance(request.vars.file, str):
form.vars.file_name = request.vars.file.filename
form.vars.file_hash = hashlib.sha256(request.vars.file.value).hexdigest()
form.vars.file_size= len(request.vars.file.value)
if form.process(onvalidation=validate_dataset_upload).accepted:
# notify upload has worked
response.flash = ('Upload successful. A validation check will be run and '
'you will get an email with the results when it finishes.')
All of this means that the validate_dataset_upload function can now check form.vars.file_hash does not already exist in the underlying table.
I have to perform two actions based on radio button selection, either download or view a document
<form method="post" action="{{ url_for('page_after_submit') }}">
<p> Your resume </p>
<div class="radio">
<label> <input type="radio" name="optionsRadios" id="optionsRadios1" value="option1" checked> Download document </label>
</div>
<div class="radio">
<label> <input type="radio" name="optionsRadios" id="optionsRadios2" value="option2"> View document </label>
</div>
<input type="submit" />
</form>
My page_after_submit has this code...
#app.route(local.URL_PREFIX + '/page_after_submit/', methods=['POST'])
def after_submit():
if 'option1' == request.form['optionsRadios']:
return/redirect ("download from this url")
if 'option2' == request.form['optionsRadios']:
return/redirect ("view in this iframe")
return (Url_for('go back to submit page if you are here')
I know my form can only have one action which is '/page_after_submit/', what code (HTML or Python in flask) I need to complete rest of my actions ??? I tried to put the iframe tags with complete download file address in the redirect for option2 but doesn't work. I also want this iframe to pop up not open a new browser window. Plus for the download, don't know what to do specially different operating system may have different path for download directory.
My goal is to not have any javascript as well, don't know if it's possible or not. Thanks in advance.
You need to craft a different response depending on how they want to see the data.
Download File
If they choose option 1, you need to set the headers and response to allow the browser to trigger a file download. Here's how you can do something like that.
View File in Iframe
If they choose option 2, you need to return an HTML response which loads the file. This can be done in an Iframe if you'd like, but it's not necessary. Here's one possible way to do that, but many others exist.
I'm using Bootstrap with Flask Python.
request.form.get("name")
#name is the name of the form element(checkbox)
<label class="btn btn-danger pzt active">
<input type="checkbox" name="name" value="1" data-id="0"> Check
</label>
When checkbox is checked, parent label has class "active", I want to get if checked box is checked. Is there any way or methods?
you can try the following:
HTML:
<div class="checkbox">
<label>
<input type="checkbox" name="check" value="edit"> New entry
</label>
</div>
In flask:
value = request.form.getlist('check')
This will give you the value of the the checkbox. Here value will be a list.
value = [u'edit']
You can also get value of multiple checkboxes with same name attribute.
I'm not familiar with Flask, but I do know how HTTP works.
If you want to know if its checked on the server side, just check if that form field exists, if request.form.get("name") gives you NULL or exception, then the checkbox should be unchecked.
If you want to know it on the client side with javascript, you can use jQuery (as jQuery is a base component of Bootstrap) as $('xxxx').is(':checked') (replace xxxx with a valid selector).
I am trying to create a simple checkbox that sends the data to server here is my html code.
<form action="." method="POST">
<div class="checksheet">
<input id="XML Parser" class="checkbox" type="checkbox"/>XML Parser
<input id="Feed Parser" class="checkbox" type="checkbox"/>Feed Parser
<input id="Text Parser" class="checkbox" type="checkbox"/>Text Parser
<input id="Case Normalization" class="checkbox" type="checkbox"/>Case Normalization
<input id="Stemmer" class="checkbox" type="checkbox"/> Stemmer
</div>
<div class="submit"><input type="submit" value="Send" name="raw_text"></div>
</form>
What I am trying to do is very similar to the question asked here: Send Data from a textbox into Flask?
But except with the text box.. I have checkboxes.
But I get this error:
Not Found
The requested URL was not found on the server.
If you entered the URL manually please check your spelling and try again.
MY server side code (in flask) is:
#app.route('/raw_text.html')
def home ():
file = "sample.xml"
contents = open(file).read()
contents = contents.decode('utf-8')
return render_template('raw_text.html', contents=contents,file=file)
#app.route('/raw_text.html',methods=['POST'])
def get_data():
print "REQUEST ",request.form()
data = request.form['raw_text']
print data
return "Processed"
Any suggestions.
Thanks
A few things:
Your checkbox elements need a name attribute, this is what is used when the data is sent to the back end. Each checkbox that is related to each other needs to have the same name.
Your action attribute needs to point to a URL. If you are posting it to the same page as the form, you can remove the attribute.
ID's cannot contain spaces.
To be accessible the check boxes need <label>s,