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1 ========================== |
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2 Outputting CSV with Django |
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3 ========================== |
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4 |
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5 This document explains how to output CSV (Comma Separated Values) dynamically |
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6 using Django views. |
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7 |
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8 To do this, you can either use the `Python CSV library`_ or the Django template |
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9 system. |
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10 |
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11 .. _Python CSV library: http://www.python.org/doc/current/lib/module-csv.html |
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12 |
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13 Using the Python CSV library |
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14 ============================ |
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15 |
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16 Python comes with a CSV library, ``csv``. The key to using it with Django is |
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17 that the ``csv`` module's CSV-creation capability acts on file-like objects, |
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18 and Django's ``HttpResponse`` objects are file-like objects. |
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19 |
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20 .. admonition:: Note |
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21 |
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22 For more information on ``HttpResponse`` objects, see |
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23 `Request and response objects`_. |
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24 |
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25 For more information on the CSV library, see the `CSV library docs`_. |
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26 |
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27 .. _Request and response objects: ../request_response/ |
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28 .. _CSV library docs: http://www.python.org/doc/current/lib/module-csv.html |
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29 |
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30 Here's an example:: |
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31 |
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32 import csv |
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33 from django.http import HttpResponse |
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34 |
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35 def some_view(request): |
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36 # Create the HttpResponse object with the appropriate CSV header. |
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37 response = HttpResponse(mimetype='text/csv') |
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38 response['Content-Disposition'] = 'attachment; filename=somefilename.csv' |
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39 |
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40 writer = csv.writer(response) |
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41 writer.writerow(['First row', 'Foo', 'Bar', 'Baz']) |
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42 writer.writerow(['Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"]) |
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43 |
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44 return response |
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45 |
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46 The code and comments should be self-explanatory, but a few things deserve a |
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47 mention: |
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48 |
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49 * The response gets a special mimetype, ``text/csv``. This tells |
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50 browsers that the document is a CSV file, rather than an HTML file. If |
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51 you leave this off, browsers will probably interpret the output as HTML, |
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52 which will result in ugly, scary gobbledygook in the browser window. |
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53 |
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54 * The response gets an additional ``Content-Disposition`` header, which |
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55 contains the name of the CSV file. This filename is arbitrary; call it |
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56 whatever you want. It'll be used by browsers in the "Save as..." |
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57 dialogue, etc. |
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58 |
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59 * Hooking into the CSV-generation API is easy: Just pass ``response`` as |
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60 the first argument to ``csv.writer``. The ``csv.writer`` function expects |
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61 a file-like object, and ``HttpResponse`` objects fit the bill. |
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62 |
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63 * For each row in your CSV file, call ``writer.writerow``, passing it an |
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64 iterable object such as a list or tuple. |
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65 |
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66 * The CSV module takes care of quoting for you, so you don't have to worry |
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67 about escaping strings with quotes or commas in them. Just pass |
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68 ``writerow()`` your raw strings, and it'll do the right thing. |
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69 |
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70 Using the template system |
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71 ========================= |
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72 |
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73 Alternatively, you can use the `Django template system`_ to generate CSV. This |
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74 is lower-level than using the convenient CSV, but the solution is presented |
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75 here for completeness. |
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76 |
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77 The idea here is to pass a list of items to your template, and have the |
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78 template output the commas in a ``{% for %}`` loop. |
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79 |
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80 Here's an example, which generates the same CSV file as above:: |
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81 |
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82 from django.http import HttpResponse |
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83 from django.template import loader, Context |
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84 |
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85 def some_view(request): |
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86 # Create the HttpResponse object with the appropriate CSV header. |
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87 response = HttpResponse(mimetype='text/csv') |
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88 response['Content-Disposition'] = 'attachment; filename=somefilename.csv' |
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89 |
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90 # The data is hard-coded here, but you could load it from a database or |
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91 # some other source. |
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92 csv_data = ( |
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93 ('First row', 'Foo', 'Bar', 'Baz'), |
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94 ('Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"), |
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95 ) |
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96 |
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97 t = loader.get_template('my_template_name.txt') |
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98 c = Context({ |
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99 'data': csv_data, |
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100 }) |
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101 response.write(t.render(c)) |
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102 return response |
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103 |
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104 The only difference between this example and the previous example is that this |
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105 one uses template loading instead of the CSV module. The rest of the code -- |
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106 such as the ``mimetype='text/csv'`` -- is the same. |
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107 |
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108 Then, create the template ``my_template_name.txt``, with this template code:: |
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109 |
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110 {% for row in data %}"{{ row.0|addslashes }}", "{{ row.1|addslashes }}", "{{ row.2|addslashes }}", "{{ row.3|addslashes }}", "{{ row.4|addslashes }}" |
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111 {% endfor %} |
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112 |
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113 This template is quite basic. It just iterates over the given data and displays |
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114 a line of CSV for each row. It uses the `addslashes template filter`_ to ensure |
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115 there aren't any problems with quotes. If you can be certain your data doesn't |
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116 have single or double quotes in it, you can remove the ``addslashes`` filters. |
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117 |
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118 .. _Django template system: ../templates/ |
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119 .. _addslashes template filter: ../templates/#addslashes |