Outputting CSV with Django¶

╰半夏微凉° 2022-03-27 14:17 89阅读 0赞

[Django | Outputting CSV with Django | Django documentation][Django _ Outputting CSV with Django _ Django documentation]

> # Outputting CSV with Django¶ #
> 
> This document explains how to output CSV (Comma Separated Values) dynamically  
> using Django views. To do this, you can either use the Python CSV library or the  
> Django template system.
> 
>   
> 
> 
> ## Using the Python CSV library¶ ##
> 
> Python comes with a CSV library, [csv][]. The key to using it with Django is  
> that the [csv][] module’s CSV-creation capability acts on file-like objects,  
> and Django’s [HttpResponse][] objects are file-like objects.
> 
> Here’s an example:
> 
>     import csv
>     from django.http import HttpResponse
>     
>     def some_view(request):
>         # Create the HttpResponse object with the appropriate CSV header.
>         response = HttpResponse(mimetype='text/csv')
>         response['Content-Disposition'] = 'attachment; filename=somefilename.csv'
>     
>         writer = csv.writer(response)
>         writer.writerow(['First row', 'Foo', 'Bar', 'Baz'])
>         writer.writerow(['Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"])
>     
>         return response
> 
> The code and comments should be self-explanatory, but a few things deserve a  
> mention:
> 
>  *  The response gets a special MIME type, *text/csv*. This tells  
>     browsers that the document is a CSV file, rather than an HTML file. If  
>     you leave this off, browsers will probably interpret the output as HTML,  
>     which will result in ugly, scary gobbledygook in the browser window.
>  *  The response gets an additional Content-Disposition header, which  
>     contains the name of the CSV file. This filename is arbitrary; call it  
>     whatever you want. It'll be used by browsers in the "Save as..."  
>     dialogue, etc.
>  *  Hooking into the CSV-generation API is easy: Just pass response as the  
>     first argument to csv.writer. The csv.writer function expects a  
>     file-like object, and [HttpResponse][] objects fit the  
>     bill.
>  *  For each row in your CSV file, call writer.writerow, passing it an  
>     iterable object such as a list or tuple.
>  *  The CSV module takes care of quoting for you, so you don't have to worry  
>     about escaping strings with quotes or commas in them. Just pass  
>     writerow() your raw strings, and it'll do the right thing.
> 
>   
> 
> 
> ### Handling Unicode¶ ###
> 
> Python's [csv][] module does not support Unicode input. Since Django uses  
> Unicode internally this means strings read from sources such as  
> [HttpRequest][] are potentially problematic. There are a few  
> options for handling this:
> 
>  *  Manually encode all Unicode objects to a compatible encoding.
>  *  Use the UnicodeWriter class provided in the [csv module's examples  
>     section][csv module_s examples section].
>  *  Use the [python-unicodecsv module][], which aims to be a drop-in  
>     replacement for [csv][] that gracefully handles Unicode.
> 
> For more information, see the Python documentation of the [csv][] module.
> 
>   
> 
> 
> ## Using the template system¶ ##
> 
> Alternatively, you can use the [*Django template system*][Django template system]  
> to generate CSV. This is lower-level than using the convenient Python [csv][]  
> module, but the solution is presented here for completeness.
> 
> The idea here is to pass a list of items to your template, and have the  
> template output the commas in a [for][] loop.
> 
> Here's an example, which generates the same CSV file as above:
> 
>     from django.http import HttpResponse
>     from django.template import loader, Context
>     
>     def some_view(request):
>         # Create the HttpResponse object with the appropriate CSV header.
>         response = HttpResponse(mimetype='text/csv')
>         response['Content-Disposition'] = 'attachment; filename=somefilename.csv'
>     
>         # The data is hard-coded here, but you could load it from a database or
>         # some other source.
>         csv_data = (
>             ('First row', 'Foo', 'Bar', 'Baz'),
>             ('Second row', 'A', 'B', 'C', '"Testing"', "Here's a quote"),
>         )
>     
>         t = loader.get_template('my_template_name.txt')
>         c = Context({
>             
>             'data': csv_data,
>         })
>         response.write(t.render(c))
>         return response
> 
> The only difference between this example and the previous example is that this  
> one uses template loading instead of the CSV module. The rest of the code --  
> such as the mimetype='text/csv' \-- is the same.
> 
> Then, create the template my\_template\_name.txt, with this template code:
> 
>     {% for row in data %}"{
>             {
>              row.0|addslashes }}", "{
>             {
>              row.1|addslashes }}", "{
>             {
>              row.2|addslashes }}", "{
>             {
>              row.3|addslashes }}", "{
>             {
>              row.4|addslashes }}"
>     {% endfor %}
> 
> This template is quite basic. It just iterates over the given data and displays  
> a line of CSV for each row. It uses the [addslashes][] template filter to  
> ensure there aren't any problems with quotes.
> 
>   
> 
> 
> ## Other text-based formats¶ ##
> 
> Notice that there isn't very much specific to CSV here -- just the specific  
> output format. You can use either of these techniques to output any text-based  
> format you can dream of. You can also use a similar technique to generate  
> arbitrary binary data; see [*Outputting PDFs with Django*][Outputting PDFs with Django] for an example.

[Django _ Outputting CSV with Django _ Django documentation]: https://docs.djangoproject.com/en/dev/howto/outputting-csv/
[csv]: http://docs.python.org/2.7/library/csv.html#csv
[HttpResponse]: http://scribefire-next/ref/request-response/#django.http.HttpResponse
[HttpRequest]: http://scribefire-next/ref/request-response/#django.http.HttpRequest
[csv module_s examples section]: http://docs.python.org/library/csv.html#examples
[python-unicodecsv module]: https://github.com/jdunck/python-unicodecsv
[Django template system]: http://scribefire-next/topics/templates/
[for]: http://scribefire-next/ref/templates/builtins/#std:templatetag-for
[addslashes]: http://scribefire-next/ref/templates/builtins/#std:templatefilter-addslashes
[Outputting PDFs with Django]: http://scribefire-next/outputting-pdf/