Emmanuel,
for examperiod I'd simply write
[...]
for period in ['DECEMBER 2011', 'MAY 2011', 'DECEMBER 2010']:
context['periods'][period] = Results.objects.all().filter(\
reg_number = 'DBA/20020/82/DU').filter(examperiod=period)
[...]
Just be careful when dealing with such comparisons since values must be
exactly the same; to state it clearly: this works always if the period
strings ("DECEMBER 2011", ...) are machine-generated and do not come from a
form (user input).
However, check this
page<https://docs.djangoproject.com/en/dev/topics/db/queries/>which
contains a very detailed analysis of Django query system.
Speaking about the templates: first of all do not take my code as the
source of the truth, things can be done in several ways.
Given that, I try to give you a bigger picture that hopefully helps you
understanding how to step further.
When introducing Django I always stress the separation between views and
templates, which is the base concept of the whole framework (MVT -
Model/View/Template).
Views are Python functions. Their purpose is to produce data and to return
data, just like any function in this world =)
Jokes apart, views are MOST OF THE TIME used to fetch data from the DB
through models and to return templates rendered in HTTP responses, so that
a browser can show them.
So, putting it simply: views extract data, templates show them (this is
somehow simplistic, but is a good starting point).
Templates are text files that are joined with a dictionary through the
Django template language. Most notably you can insert in the template
elements of the dictionary just inserting "{{ key }}" where "key" is the
dictionary key you want to fetch. If the value you get from the dictionary
is an object or another dictionary, you can use the dotted notation to
access its attributes or keys. So if you write in a template {{ obj }} the
template expects you to pass a dictionary which contains the key 'obj' and
some value that can be printed. If you write {{ obj.name }} the template
expects you to pass a dictionary that contains the key 'obj', which in turn
is something that can be accessed through the 'name' attribute lookup; for
example, a Python object with a 'name' attribute.
Context is the dictionary that the view passes to the template when calling
render_to_response().
So my advice was to select what you pass in the context, since passing
locals() is overkill; you pass the template every variable you have, and
this can result in passing a very big dictionary! Moreover, it is not clear
to another programmer (that is you in a month) what the template really
needs. If you template is made to represent a set of objects in table just
extract the set of objects and pass them to the view. To give you an
example:
*MODEL*
class Exam(models.Model):
label = models.CharField(max_length=30)
*VIEW*
def someview(request):
my_list_of_objects = Exam.objects.filter(label='somelabel')
context = {'objects':my_list_of_objects}
return render_to_response('results.html', context, context_instance =
RequestContext(request))
*TEMPLATE*
[...]
<table>
{% for obj in objects %}
<td><tr>{{obj.label}}</tr></td>
{% endfor %}
</table>
[...]
This can also be written (and is perfectly correct):
*VIEW*
def someview(request):
my_list_of_objects = *[exam.label for exam
in*Exam.objects.filter(label='somelabel')
*]*
context = {'object':my_list_of_object}
return render_to_response('results.html', context, context_instance =
RequestContext(request))
*TEMPLATE*
[...]
<table>
{% for obj in objects %}
<td><tr>{{obj}}</tr></td>
{% endfor %}
</table>
[...]
(Please note that in the second example I left the previous nomenclature
for clarity's sake - in a real case I'd call the values 'labels' and not
'objects')
Hope this helps you. Regards,
Leo
Leonardo Giordani
Author of The Digital Cat <http://lgiordani.github.com>
My profile on About.me <http://about.me/leonardo.giordani> - My GitHub
page<https://github.com/lgiordani>- My Coderwall
profile <https://coderwall.com/lgiordani>
2013/10/3 +Emmanuel <eluse...@gmail.com>
> Thanks for the update and the code. Been trying to make sense of the code
> and trying to get it to work. This is my first project so I still have some
> challenges:
>
>
> - My model contains a field examperiod = models.CharField(max_length =
> 100) which I need to use to filter. How exactly do I apply that in
> <further_filter_by_period>. I can't seem to get it to work.
> - The code you provided to be used in the template is a little
> difficult for me to comprehend. Previously, I could use query.coursecode,
> query.examcode, etc to populate the specific cells in the table. I
> can't seem to figure out how to do that with the new piece of code.
>
> Thanks for the help :)
>
> On Wednesday, October 2, 2013 4:32:22 PM UTC+3, Leo wrote:
>
>> Ok, now I get the point. I STRONGLY suggest to avoid performing big
>> computations while rendering templates, so I think it is better for you to
>> try something like
>>
>> def results_page(request):
>> context = {}
>> context.update(locals())
>> context['periods'] = {}
>> for period in ['DECEMBER 2011', 'MAY 2011', 'DECEMBER 2010']:
>> context['periods'][period] = Results.objects.all().filter(\
>> reg_number = 'DBA/20020/82/DU').filter(<**
>> further_filter_by_period>)
>> return render_to_response('results.**html', context,
>> context_instance = RequestContext(request))
>>
>> and in template
>>
>> {% for period,results in periods.items %}
>> <table class='table table-striped table-bordered'>
>> [...]
>> Here you can use {{period}}, which is in turn 'DECEMBER 2011', 'MAY
>> 2011', and so on, and
>> {{result}} that encompasses the values extracted from the DB.
>> [...]
>> </table>
>> {% endfor %}
>>
>> I included a filter(<further_filter_by_**period>) since I do not know
>> the models, so I do not know how you can filter out by examination period.
>>
>> Please note that I would not pass the whole locals() dict to the view,
>> but carefully select what I need in the template.
>>
>> Speaking about your filter
>>
>> @register.filter
>> def periodofexamination(periodofex**am):
>> periodofexam = ['DECEMBER 2011', 'MAY 2011', 'DECEMBER 2010']
>> for period in periodofexam:
>> return period
>>
>> I think you misunderstood the filter role, which is, indeed, to filter,
>> things. Here, the input periodofexam variable is not filtered, but
>> overwritten. Furthermore, you use return in a for loop, so the result of
>> your filter is 'DECEMBER 2011' irrespective of the input value.
>>
>> Please check the above code, I wrote it directly in the mail composer, so
>> bugs are certainly lurking.
>>
>> Let me know if you succeed in solving the problem
>>
>> Leo
>>
>>
>>
>>
>> Leonardo Giordani
>> Author of The Digital Cat <http://lgiordani.github.com>
>> My profile on About.me <http://about.me/leonardo.giordani> - My GitHub
>> page <https://github.com/lgiordani> - My Coderwall
>> profile<https://coderwall.com/lgiordani>
>>
>>
>> 2013/10/2 +Emmanuel <elus...@gmail.com>
>>
>>> Here's the view:
>>> def results_page(request):
>>> queryset = Results.objects.all().filter(**reg_number =
>>> 'DBA/20020/82/DU')
>>> return render_to_response('results.**html', locals(),
>>> context_instance = RequestContext(request))
>>>
>>> Please note that, so far, there's nothing wrong with the view. Using the
>>> custom filter at the output level is where the issue is.
>>> What I want to do is something close to this (note the bold items):
>>>
>>> *{% for query in queryset|periodofexamination %}*
>>> <table class='table table-striped table-bordered'>
>>> <thead><th>Course Code</th><th>Course Name</th><th>Course
>>> Work</th><th>Exam</th><th>**Grade</th><th>GPA</th><th>**Year</th><th>Exam
>>> Period</th></thead>
>>>
>>> <tr><td>{{ query.coursecode}}</td><td>{{**
>>> query.coursename}}</td><td>{{**query.coursework}}</td><td>{{**
>>> query.exam}}</td><td>{{query.**exam|grade}}</td><td>{{query.**
>>> exam|gpa}}</td><td>{{query.**academicyear}}</td><td>{{**
>>> query.examperiod}}</td></tr>
>>>
>>> </table>
>>> {% endfor %}
>>> {% endblock %}
>>>
>>> On Wednesday, October 2, 2013 3:00:40 PM UTC+3, Leo wrote:
>>>
>>>> Can you perhaps paste the view you are using to render the template? So
>>>> I can try and help your with some code
>>>>
>>>> Leonardo Giordani
>>>> Author of The Digital Cat <http://lgiordani.github.com>
>>>> My profile on About.me <http://about.me/leonardo.giordani> - My GitHub
>>>> page <https://github.com/lgiordani> - My Coderwall
>>>> profile<https://coderwall.com/lgiordani>
>>>>
>>>>
>>>> 2013/10/2 +Emmanuel <elus...@gmail.com>
>>>>
>>>>> That's what I have been trying to do for quite sometime now! I can't
>>>>> seem to get the code right.
>>>>>
>>>>>
>>>>> On Wednesday, October 2, 2013 2:13:25 PM UTC+3, Leo wrote:
>>>>>
>>>>>> I'd cycle in the template through a list of exam periods, printing a
>>>>>> table for each cycle.
>>>>>> You have to pass the list of exam periods in the context of your view.
>>>>>>
>>>>>> Try and let me know.
>>>>>>
>>>>>> Regards,
>>>>>> Leo
>>>>>>
>>>>>>
>>>>>> Leonardo Giordani
>>>>>> Author of The Digital Cat <http://lgiordani.github.com>
>>>>>> My profile on About.me <http://about.me/leonardo.giordani> - My GitHub
>>>>>> page <https://github.com/lgiordani> - My Coderwall
>>>>>> profile<https://coderwall.com/lgiordani>
>>>>>>
>>>>>>
>>>>>> 2013/10/2 +Emmanuel <elus...@gmail.com>
>>>>>>
>>>>>>> Am working on a Django project that retrieves a student's details
>>>>>>> from the database, filters them based on the 'period of examination'
>>>>>>> (this
>>>>>>> is implemented as a python list in a custom filter) and displays the
>>>>>>> output.
>>>>>>>
>>>>>>> *Here is my custom filter:*
>>>>>>>
>>>>>>> @register.filter
>>>>>>> def periodofexamination(**periodofex****am):
>>>>>>> periodofexam = ['DECEMBER 2011', 'MAY 2011', 'DECEMBER 2010']
>>>>>>> for period in periodofexam:
>>>>>>> return period
>>>>>>>
>>>>>>> *The template for displaying the output:*
>>>>>>>
>>>>>>> {% extends 'base.html' %}
>>>>>>> {% load results_extras %}
>>>>>>> {% block title %}My Results{% endblock %}
>>>>>>>
>>>>>>> {% block content %}
>>>>>>> <h3> My Tentative Examination Results</h3>
>>>>>>> <div class="alert alert-info">The results displayed below are
>>>>>>> tentative and for information purposes only.</div>
>>>>>>>
>>>>>>> <table class='table table-striped table-bordered'>
>>>>>>> <thead><th>Course Code</th><th>Course Name</th><th>Course
>>>>>>> Work</th><th>Exam</th><th>**Grad****e</th><th>GPA</th><th>**Year</**
>>>>>>> th**><th>Exam Period</th></thead>
>>>>>>> {% for query in queryset %}
>>>>>>>
>>>>>>> <tr><td>{{ query.coursecode}}</td><td>{{**q****
>>>>>>> uery.coursename}}</td><td>{{**qu****ery.coursework}}</td><td>{{**que
>>>>>>> ****ry.exam}}</td><td>{{query.**exam****|grade}}</td><td>{{query.**
>>>>>>> exam|****gpa}}</td><td>{{query.**academic****year}}</td><td>{{**
>>>>>>> query.**examper**iod}}</td></tr>
>>>>>>>
>>>>>>> {% endfor %}
>>>>>>> </table>
>>>>>>> {% endblock %}
>>>>>>>
>>>>>>> *The output:*
>>>>>>> See the attached file (screenshot.png)
>>>>>>>
>>>>>>> *The challenge:*
>>>>>>> I would like to be able have the student results for a given exam
>>>>>>> period to appear each in their own table, for instance, all the results
>>>>>>> for
>>>>>>> exam period 'December 2011' should be in one table, all the results for
>>>>>>> exam period 'December 2010' should be in a different table. Currently,
>>>>>>> all
>>>>>>> the results appear in one table.
>>>>>>> How do I implement this using a custom filter?
>>>>>>> Thanks.
>>>>>>>
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