Nov 14, 2022
6 min read
DataTables.js for Django
Python Classes to Implement AJAX Data Table in Django
Hi. In this text, I am not going to write everything step by step. Instead of writing step by step, I’ll explain in a few lines what I have done to implement dynamic data tables that are created by using DataTables.js.
I created a repo to share example code. You can access the example by using the link below.
Data Table Factory
Thanks for this class, we can easily grab the appropriate DataTableFactory class. By default, I created a factory class for AWS connection. You can directly present your SQL data with this class.
import pandas as pd
from .factories.aws_dtfactory import AWSDataTableFactory
class DataTableFactory(object):
"""Data Table Factory class to generate a related sub data table factory class
"""
@staticmethod
def get_factory(query_engine):
"""Get a query_engine related data table factory object
Args:
query_engine (str): [aws] To get related factory class
Returns:
an object that is created by using query_engine related data table factory class
"""
if query_engine == "aws":
return AWSDataTableFactory(query_engine)
else:
return pd.DataFrame()AWS Data Table Factory
By using this class we can easily filter the queried data with AJAX filter parameters. If you want to deeply examine the filtering method, you can look at filter_by_request_args method.
from sqlalchemy import create_engine
import pandas as pd
def get_redshift_con():
user = ""
password = ""
host = ""
port = ""
database = ""
return create_engine(
f'postgresql+psycopg2://{user}:{password}@{host}:{port}/{database}'
)
class AWSDataTableFactory(object):
def __init__(self, query_engine):
"""Create an AWSDataTableFactory object
AWS specific data table data generator
Args:
query_engine (str): "aws"
"""
self.query_engine = query_engine
self.query = None
self.columns = []
self.displayed_columns = []
def set_query(self, query):
"""Set factory's query
Args:
query (str): The query will be executed
Returns:
It doesn't return anything. It sets the factory's query.
"""
self.query = query
self.set_columns()
def set_columns(self):
"""Set factory's columns
Returns:
It doesn't return anything. It sets the factory's columns.
"""
limited_query = self.query.split('limit')[0]
limited_query += " limit 1"
res = self.get_data(limited_query)
self.columns = [col for col in res.columns]
self.displayed_columns = self.columns[:4]
def set_displayed_columns(self, column_list):
"""Set factory's displayed columns
Args:
column_list (list): List of columns
"""
self.displayed_columns = column_list
def get_displayed_columns_for_data_table(self):
"""Get data table columns for AJAX request
Returns:
list: List of dictionaries
"""
return [{'data': col} for col in self.displayed_columns]
def get_data(self, query=None, *args, **kwargs):
"""Get (extract) data from the source by executing the query with the engine
Args:
query (str): The query will be executed
*args:
**kwargs:
Returns:
table_data (pd.DataFrame): Returns the data that extracted from AWS
"""
if self.query is None:
raise NotImplementedError(
'Firstly you have to set a query for the engine')
con = get_redshift_con()
if query is None:
table_data = pd.read_sql(con=con, sql=self.query, *args, **kwargs)
else:
table_data = pd.read_sql(con=con, sql=query, *args, **kwargs)
return table_data
def filter_by_request_args(self, **kwargs):
"""Filter and sort the data by using request.GET parameters
Args:
**kwargs: request.GET
Returns:
dict: to use in the frontend with ajax data table requests
"""
draw = int(kwargs.get('draw', None)[0])
length = int(kwargs.get('length', None)[0])
start = int(kwargs.get('start', None)[0])
search_value = kwargs.get('search[value]', None)[0]
order_column = kwargs.get('order[0][column]', None)[0]
order = kwargs.get('order[0][dir]', None)[0] # asc or desc
factory_filters = [f for f in kwargs if f.startswith('factory_filter')]
order_column = self.columns[int(order_column)]
queryset = self.get_data()
############ factory_filters applying ############
if len(factory_filters) > 0:
for ff in factory_filters:
query_col = ff.split('factory_filter-')[1]
query_val = kwargs.get(ff)[0]
if query_val != 'All':
queryset = queryset[queryset[query_col] == query_val]
total = len(queryset)
if search_value:
queryset = queryset[queryset.apply(lambda row: row.astype(
str).str.contains(search_value).any(), axis=1)]
count = len(queryset)
queryset.sort_values(
by=order_column, ascending=False if order == 'desc' else True, inplace=True)
queryset = queryset[self.displayed_columns]
return {
'data': queryset,
'count': count,
'total': total,
'draw': draw,
'start': start,
'length': length
}Data Table View
This is our class based view. In this class, we use parameters that are coming from urls.py .
from django.shortcuts import render
from django.contrib.auth.decorators import login_required
from django.views import View
from .utilities.dtfactory import DataTableFactory
from django.utils.decorators import method_decorator
from django.core.exceptions import PermissionDenied
from django.http import JsonResponse
@method_decorator(login_required, name="dispatch")
class DataTableView(View):
"""Data table class based view
This view can get the parameters below in the as_view function to use in the view
Args:
page_name (str): To display in page
query_engine (str): [aws] To create a DataTableFactory for querying the data source
query (str): To execute the query by using the connection that is created with query_engine
query_parameters (dict): Additional parameters to pass into to exec_sql method of the factory
permission (str): The needed permission to access the url
"""
page_name = ""
query_engine = ""
query = ""
query_parameters = {}
permission = ""
filters = []
def get(self, request, *args, **kwargs):
# todo: kolon seçimi eklenecek
data_table_factory = DataTableFactory.get_factory(self.query_engine)
data_table_factory.set_query(self.query)
if request.GET.get('ajax_factory_loader', None) is not None:
filter_args = data_table_factory.filter_by_request_args(
**request.GET)
data = filter_args['data'].to_dict(orient='records')
data = data[filter_args['start'] :filter_args['start'] + filter_args['length']]
result = {'data': data, 'draw': filter_args['draw'], 'recordsTotal': filter_args['total'],
'recordsFiltered': filter_args['count']}
return JsonResponse(result)
return render(
request,
"datagateway/data_table.html",
context={"page_name": self.page_name,
'filters': self.filters, 'factory': data_table_factory},
)
def dispatch(self, request, *args, **kwargs):
if not request.user.has_perm(self.permission):
raise PermissionDenied(
"You do not have permission to view this page")
return super().dispatch(request, *args, **kwargs)urls.py
In this file, we pass parameters to use in the class based view. We can define required permission, query engine, query and static filters etc.
from django.urls import path
from . import views
app_name = "dtfactory"
urlpatterns = [
path(
"",
views.DataTableView.as_view(
page_name="Data Table Demo",
query_engine="aws",
query=f"select * from QUERY",
permission="custom_app.can_view_data_table_page",
filters=[
{'filter_column': 'custom_region', 'display_name': 'Region', 'type': 'static',
'filter_values': ['All', 'TR', 'EN']}
]
),
name="dt_demo",
),
]Template File
In this file we use the passed factory parameters that are coming from backend.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Data Table Demo</title>
<link
rel="stylesheet"
href="cdn.datatables.net/1.13.1/css/jquery.dataTables.min.css"
/>
</head>
<body>
<table id="demoDT">
<thead>
<tr>
{% for col in factory.displayed_columns %}
<th>{{ col }}</th>
{% endfor %}
</tr>
</thead>
<tbody></tbody>
</table>
<script src="cdn.datatables.net/1.13.1/js/jquery.dataTables.min.js"></script>
<script>
$(document).ready(function () {
function customExportAction(e, dt, button, config) {
var self = this;
var oldStart = dt.settings()[0]._iDisplayStart;
dt.one('preXhr', function (e, s, data) {
// Just this once, load all data from the server...
data.start = 0;
data.length = 2147483647;
dt.one('preDraw', function (e, settings) {
// Call the original action function
if (button[0].className.indexOf('buttons-copy') >= 0) {
$.fn.dataTable.ext.buttons.copyHtml5.action.call(self, e, dt, button, config);
} else if (button[0].className.indexOf('buttons-excel') >= 0) {
$.fn.dataTable.ext.buttons.excelHtml5.available(dt, config) ?
$.fn.dataTable.ext.buttons.excelHtml5.action.call(self, e, dt, button, config) :
$.fn.dataTable.ext.buttons.excelFlash.action.call(self, e, dt, button, config);
} else if (button[0].className.indexOf('buttons-csv') >= 0) {
$.fn.dataTable.ext.buttons.csvHtml5.available(dt, config) ?
$.fn.dataTable.ext.buttons.csvHtml5.action.call(self, e, dt, button, config) :
$.fn.dataTable.ext.buttons.csvFlash.action.call(self, e, dt, button, config);
} else if (button[0].className.indexOf('buttons-pdf') >= 0) {
$.fn.dataTable.ext.buttons.pdfHtml5.available(dt, config) ?
$.fn.dataTable.ext.buttons.pdfHtml5.action.call(self, e, dt, button, config) :
$.fn.dataTable.ext.buttons.pdfFlash.action.call(self, e, dt, button, config);
} else if (button[0].className.indexOf('buttons-print') >= 0) {
$.fn.dataTable.ext.buttons.print.action(e, dt, button, config);
}
dt.one('preXhr', function (e, s, data) {
// DataTables thinks the first item displayed is index 0, but we're not drawing that.
// Set the property to what it was before exporting.
settings._iDisplayStart = oldStart;
data.start = oldStart;
});
// Reload the grid with the original page. Otherwise, API functions like table.cell(this) don't work properly.
setTimeout(dt.ajax.reload, 0);
// Prevent rendering of the full data to the DOM
return false;
});
});
// Requery the server with the new one-time export settings
dt.ajax.reload();
}
$("#demoDT").DataTable({
processing: true,
serverSide: true,
lengthChange: true,
ajax: {
url: "{{ request.get_full_path }}", // send ajax request to itself for filtering and paginating the data
data: {ajax_factory_loader:true},
},
columns: {{ factory.get_displayed_columns_for_data_table | safe }},
"dom": 'Blfrtip',
"buttons": [
{
extend: 'excel',
text: 'Excel',
filename: "{{page_name}}",
header: true,
title: "{{page_name}}",
"action": customExportAction
},
{
extend: 'csv',
text: 'CSV',
filename: "{{page_name}}",
header: true,
title: "{{page_name}}",
"action": customExportAction
},
{
extend: 'pdf',
text: 'PDF',
filename: "{{page_name}}",
header: true,
title: "{{page_name}}",
"action": customExportAction
},
],
})
.buttons()
.container()
.appendTo("#download-action-area")
});
</script>
</body>
</html>Finally
Hopefully, it helps you to use DataTables.js in your Django projects. I know it is too short. However, I believe that you can understand the code by just looking at it. If you want to extend the Factory, you should implement your own factories in DataTableFactory class.
Regards
