I am struggling with something that is probably very basic: I need to generate a form with marks for my University database application. Each student in each module has a class got "Performance" that stores all the marks for the module. There are different assessments and the Performance class calculates the average for them.
I need to be able to enter, for example, all the marks for the first assessment, and I did that with a dynamically generated Django Form as a table in the template:
{% for performance in performances %}
<tr>
<td>
{{ performance.student }}
</td>
<td>
{% if to_mark == 1 %}
<input type="text" class="input-mini" name="{{ student.student_id }}" value="{{ performance.assessment_1 }}">
{% else %}
{{ performance.assessment_1 }}
{% endif %}
</td>
And the same for the other assessments (to_mark gets passed on by views.py to indicate which assessments needs to be marked here)
I have failed to use Inlineformfields and therefore decided to generate a form dynamically and validate it with Javascript, also because the validation is simple (has to be a number between 1 and 100), and also because I want to use Javascript to calculate the average on the fly.
My problem is that I have no clue about Javascript. All the tutorials (like this one http://www.w3schools.com/js/js_form_validation.asp) use the name of the form field in the Javascript function, but in my case that name is dynamically generated, so that I can access it easily in the views.py:
if student.student_id in request.POST:
tmp = request.POST[student.student_id]
try:
mark = int(tmp)
if mark in range(0, 100):
performance = Performance.objects.get(student=student, module=module)
if to_change == 1:
performance.assessment_1 = mark
...and so on for the other assessments
except ValueError:
pass (in case someone accidentally enters a letter and not a number)
Is there a way I can use Javascript to address my form fields? Or should I use a different approach than taking the student_id as the name to read it out? How could I do that?
Thanks,
Tobi
There are at least 3 ways to get to the form fields using JavaScript:
By ID, by CSS class or by DOM traversal. If you're not familiar with JavaScript, I would suggest finding a django-friendly client-side form validator like: https://code.google.com/p/django-ajax-forms/
Related
I am trying to create custom data to save into the customer object, which I could then access on a different page. I have an input like this
<input type="hidden" id="{{ formId }}-score" name=contact[score]>
I created an exam page that uses a script to calculate the score, which is then sending the value to that input. I am trying to save that value into the customer object which I could then access on a different page like this:
{% if customer.score > 11 %} <h1> You Passed </h1> {% endif %}
In Shopify, using tags we can save custom data of the customer. You will need to add tags in the name like this: name="customer[tags]"
You can pass the value as per your need like this: value="score_11"
You can fetch the value like this: customer.tags
You can use tags in your condition.
{% if customer.tags > score_11 %}
I am trying to create a dependable dropdown on Django but since my JavaScript/ajax knowledge is not great, I have hit rock bottom. Note: I have read previous questions on this matter but none of them fully solved my problem.
Problem Description:
Due to my database size, I am retrieving partial data from the server whenever a view is requested. This makes my job of using forms harder since I am using the username of the user to filter my server. Here is a simplified version of my code.
urls.py
urlpatterns = [
url(r'^SpecificVessel', views.SpecificVessel, name="goSpecificVessel"),
]
views.py
#login_required
def SpecificVessel(request):
#Get the username to filter the tables from SQL Server:
username = None
if request.user.is_authenticated:
username = request.user.username
#Get the shipnames.
cursor.execute("select distinct SHIPNAME from Table where [GROUP]=" + "'" + username + "'")
row = cursor.fetchall()
df_listofships = pd.DataFrame(data=row, columns=['SHIPNAME'])
shipnames = list(df_listofships['SHIPNAME'].tolist()) # LIST FOR SHIP SELECTION
#Get All the data from database.
cursor.execute("select * from Table2 where [GROUP]=" + "'" + username + "'")
row = cursor.fetchall()
df = pd.DataFrame(data=row)
colnames = list(dftrans.columns.values.tolist()) #LIST FOR YEAR DROPDOWN SELECTION
#getting the dropdown selections:
Dropdown_shipname = request.POST.get('Dropdown_shipname')
Dropdown = request.POST.getlist('Dropdown')
return render(request, 'SpecificVessel.html',
{'colnames': colnames, 'Dropdown': Dropdown, 'shipnames': shipnames, 'Dropdown_shipname': Dropdown_shipname,})
SpecificVessel.html
<form method="post">
{% csrf_token %}
<div class="form-group col-md-4">
<label for="Dropdown_shipname"><b>Select Vessel</b></label>
<select name="Dropdown_shipname" id="Dropdown_shipname" data-style="btn-default" class="selectpicker form-control" >
{% for i in shipnames %}
<option value="{{ i }}" {% if Dropdown_shipname == i %} selected {% endif %}>{{ i }} </option>
{% endfor %}
</select>
</div>
<div class="form-group col-md-4">
<label for="Dropdown"><b> Select Month </b></label>
<select name="Dropdown" id="Dropdown" data-style="btn-default" class="selectpicker form-control" multiple>
{% for i in colnames %}
<option value="{{ i }}" {% if Dropdown == i %} selected {% endif %} >{{ i }} </option>
{% endfor %}
</select>
</div>
<div class="form-group col-md-1 margin_top_25">
<input type="submit" value="Submit" />
</div>
</form>
What is the problem?
The solution I have in the code above provides me with independent dropdowns. That is, whenever there is a mismatch, it throws me an error. I have been trying to approach this in different way, however, after long research online, I found out that javascript or ajax may be the way to go about this. My question is this: Is there any way in which I could get what the user has selected in Dropdown_shipname before he submits the results? If yes, how would you solve this problem?
I hope I was clear enough. Please let me know if I should explain the problem any better.
There's a lot I feel I need to address before answering your main question.
The if request.user.is_authenticated bit is unnecessary; you already decorate the view with #login_required, so there's no way the user isn't authenticated.
Where does cursor come from? It doesn't look like you're using Django's database stuff (the ORM, or even raw cursors), but something else? Why is that?
Having a global cursor may lead to trouble down the line in production, when it's being shared between requests in a multithreaded situation. (Using Django's database functionality the database connections are correctly reset between requests, and each thread gets its own connection.)
Your SQL queries are vulnerable to SQL injection attacks, since you're just concatenating strings together. You need to use placeholders (parametrized queries) instead. How that's done depends on the database and database driver you're using.
You definitely don't need Pandas and a Pandas dataframe to extract the data from your database result! (My pet peeve: useless use of Pandas.)
The first retrieval would be shipnames = [row[0] for row in cursor].
The second retrieval would be colnames = [d[0] for d in cursor.description] (or similar; depends on your database). (However, you really don't want to fetch a number of rows just to get the column names; one row, e.g. LIMIT 1 in standard SQL, would do.)
You should be using Django forms to manage, well, forms. That way you don't need to manage rendering the <select>s and <option>s and selecteds manually.
This view would likely become a FormView subclass.
You say "This makes my job of using forms harder since I am using the username of the user to filter my server.", but that's a non-issue. You can well pass in your Django request, or just the User, or an username, to a custom form class, and have it modify or even add fields dynamically to the form based on it.
That said, the most minimal solution here is a tiny bit of JavaScript, to refresh the page with an added query string argument for the first selection. That is, when the user changes the shipname field, you'd refresh the page with e.g. ?shipname=selection-here, and deal with figuring out the correct choices for the other field in your view code.
The most minimal way I can think of is
<script>
document.getElementById("Dropdown_shipname").addEventListener("change", (event) => {
location.href = `?shipname=${event.target.value}`;
}, false);
</script>
Beyond that, you could use an AJAX request to selectively refresh only part of the page, and beyond that, maybe refactor the form into, say, a React.js or Vue.js component that deals with the form.
But either way, no, you're not going to be able to dynamically change the other field without JavaScript.
I have a problem with setting up single checkbox in flask application, which I would like to use checkbox as button to control LED diode. When it's checked, light is on and when it's not, it's off. The mechanism already works, but every-time, when I check the checkbox, the checkbox will uncheck itself (It submits the checkbox). I need it to hold its actual value after the submit.
I tried to use jinja2 If statement to put attribute "checked" into HTML code, but it didn't work. If I could read and change the value directly from python, I would be able to easily modify it with something like this
{% if value="on"%} checked {% else %} "" {% endif %}
but I really don't know how :/.
autocomplete="off" doesn't work in this case.
I don't want to use additional variables, when this code already needs changes.
<input onchange="$('#check').submit();" type="checkbox" name="ledcheck" class="form-check-input" id="exampleCheck" {% dunno what to write here pls help :c %}/>
if 'ledcheck' in request.form:
if database['actValues']['digital']['led'] == 1:
database['actValues']['digital']['led'] = 0
a.digital_write(LED_PIN,0)
else:
database['actValues']['digital']['led'] = 1
a.digital_write(LED_PIN,1)
Whole code is on GitHub here.
I am trying to use a javascript variable in a python dictionary in html, is this possible? Any help would be great.
e.g if I had a dictionary - current_data
var num_key = "4";
alert( {{ current_data[num_key] }} );
If I do the following it works perfectly,
alert( {{ current_data["4"] }} );
But with the javascript variable, it won't work.
Thanks again.
No, while you can use Jinja to create JavaScript embedded in <script> tags, you cannot use it the other way around. When Flask renders this page it's static. The page does not still have blocks of code inside {{ }} or {% %}, it holds the result of those operations. However, there are other options. You could put the contents of current_data into hidden input with the keys as the id attributes.
View
{% for key in current_data %}
<input id="{{ key }}" type="hidden" value="{{ current_data[key] }}"/>
{% endfor %}
JavaScript
var num_key = "4";
alert(document.getElementById(num_key).value);
One extra piece of advice, it's not good practice to embed JavaScript into your html. You should have a separate .js file containing this and then include it in your html.
I'm developing a Flask application that contains a ton of inputs. Some the inputs depend on other inputs so there is some DOM manipulation to expose these dependent inputs. I would like for the application to remember the DOM state when the user goes back so the user doesn't have to reenter everything. What's the best way to do this?
Below demonstrates what I think should work. I have an input box that takes a number. There is also a button that adds the same input field to the DOM. When the user clicks submit, these inputs are appended to input_list and the list is displayed on the UI. Because input_list is a global variable, the application will remember these inputs and their values (even if I go back in the browser or reload the page) - this is what I'm looking for.
Again, I'm not sure if this is the best way to do it. I know flask.g can be used to store application globals but I'm not sure this is the right use case for that (I've only seen that used to store database connections). I've also heard cookies may be useful for remembering changes in the DOM. Any thoughts/examples would be helpful and if anyone thinks my way is okay, I'd appreciate feedback on my code below.
app.py:
#app.route('/input_page', methods=['GET', 'POST'])
def input_page():
global input_list
input_list = []
if request.method == 'POST':
if request.form.get('empty_list'):
input_list = []
elif request.form.get('submit_list'):
input_list = [int(i) for i in request.form.getlist('x')]
return render_template('input_page.html', input_list=input_list)
input_page.html:
<p>{{ input_list }}</p>
<form method="POST" action="/input_page">
<div id="input_container">
{% if input_list %}
{% for i in input_list %}
<input type="number" name="x" value="{{ input_list[loop.index0] }}">
{% endfor %}
{% else %}
<input type="number" name="x">
{% endif %}
</div>
<button type="button" id="add_input">Add Input</button>
<input type="submit" value="Submit List" name="submit_list">
<input type="submit" value="Empty List" name="empty_list">
</form>
<script>
$(document).ready(function(){
$('#add_input').click(function(){
var $new_input = $('<input>', {type: 'number', name: 'x'});
$('#input_container').append($new_input);
});
})
</script>
You seem to be on the right track. However, I would shy away from a global variable because that essentially exposes the variable to other concurrent clients. I would however, recommend using the Flask session object:
from flask import Flask, session, ... # other flask modules you already have imported
Then in your Python code, you'd use:
def input_page():
if request.method == 'POST':
if request.form.get('empty_list'):
session['input_list'] = []
elif request.form.get('submit_list'):
session['input_list'] = [int(i) for i in request.form.getlist('x')]
input_list = session.get('input_list', False) # create an input_list var that either grabs the 'input_list' object from the session object or defaults to False if no key found
return render_template('input_page.html', input_list=input_list)