blocks|key|774426|text|您需要在Django文档中查看FileField+and+FieldFile，尤其是FieldFile.save()。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|774427|基本上，声明为FileField的字段在被访问时会提供一个FieldFile类的实例，该实例提供了几种与底层文件交互的方法。所以，你需要做的是：|style|CODE|774428|self.license_file.save(new_name,+new_contents)|code-block|syntax|javascript|774429|其中，new_name是您希望分配的文件名，new_contents是文件的内容。请注意，new_contents必须是django.core.files.File或django.core.files.base.ContentFile的实例(有关详细信息，请参阅手册的给定链接)。|774430|这两个选择可以归结为：|774431|from+django.core.files.base+import+ContentFile,+File

#+Using+File
with+open('/path/to/file')+as+f:
++++self.license_file.save(new_name,+File(f))

#+Using+ContentFile
self.license_file.save(new_name,+ContentFile('A+string+with+the+file+content'))|774432|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.djangoproject.com/en/stable/ref/models/fields/#filefield-and-fieldfile|1|https://docs.djangoproject.com/en/stable/ref/models/fields/#django.db.models.fields.files.FieldFile.save^0|F|N|0|16|G|1|0|7|9|T|9|0|0|3|8|M|C|19|C|1O|M|2B|Y|0|0|0^^$0|@$1|2|3|4|5|6|7|12|8|@]|9|@$A|13|B|14|1|15]|$A|16|B|17|1|18]]|C|$]]|$1|D|3|E|5|6|7|19|8|@$A|1A|B|1B|F|G]|$A|1C|B|1D|F|G]]|9|@]|C|$]]|$1|H|3|I|5|J|7|1E|8|@]|9|@]|C|$K|L]]|$1|M|3|N|5|6|7|1F|8|@$A|1G|B|1H|F|G]|$A|1I|B|1J|F|G]|$A|1K|B|1L|F|G]|$A|1M|B|1N|F|G]|$A|1O|B|1P|F|G]]|9|@]|C|$]]|$1|O|3|P|5|6|7|1Q|8|@]|9|@]|C|$]]|$1|Q|3|R|5|J|7|1R|8|@]|9|@]|C|$K|L]]|$1|S|3|-4|5|6|7|1S|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]|10|$5|V|W|X|C|$Y|11]]]]

You want to have a look at <a href="https://docs.djangoproject.com/en/stable/ref/models/fields/#filefield-and-fieldfile" rel="noreferrer">FileField and FieldFile</a> in the Django docs, and especially <a href="https://docs.djangoproject.com/en/stable/ref/models/fields/#django.db.models.fields.files.FieldFile.save" rel="noreferrer">FieldFile.save()</a>.
Basically, a field declared as a <code>FileField</code>, when accessed, gives you an instance of class <code>FieldFile</code>, which gives you several methods to interact with the underlying file. So, what you need to do is:
<pre><code>self.license_file.save(new_name, new_contents)
</code></pre>
where <code>new_name</code> is the filename you wish assigned and <code>new_contents</code> is the content of the file. Note that <code>new_contents</code> must be an instance of either <code>django.core.files.File</code> or <code>django.core.files.base.ContentFile</code> (see given links to manual for the details).
The two choices boil down to:
<pre><code>from django.core.files.base import ContentFile, File

# Using File
with open('/path/to/file') as f:
 self.license_file.save(new_name, File(f))

# Using ContentFile
self.license_file.save(new_name, ContentFile('A string with the file content'))
</code></pre>

blocks|key|774465|text|公认的答案当然是一个很好的解决方案，但以下是我从一个角度生成CSV并为其提供服务的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|774466|我认为把这个放在这里是值得的，因为我花了一点时间才得到所有想要的行为(覆盖现有文件，存储到正确的位置，不创建重复文件等)。|774467|Django+1.4.1|774468|Python+2.7.3|774469|#Model
class+MonthEnd(models.Model):
++++report+=+models.FileField(db_index=True,+upload_to='not_used')

import+csv
from+os.path+import+join

#build+and+store+the+file
def+write_csv():
++++path+=+join(settings.MEDIA_ROOT,+'files',+'month_end',+'report.csv')
++++f+=+open(path,+"w%2Bb")

++++#wipe+the+existing+content
++++f.truncate()

++++csv_writer+=+csv.writer(f)
++++csv_writer.writerow(('col1'))

++++for+num+in+range(3):
++++++++csv_writer.writerow((num,+))

++++month_end_file+=+MonthEnd()
++++month_end_file.report.name+=+path
++++month_end_file.save()

from+my_app.models+import+MonthEnd

#serve+it+up+as+a+download
def+get_report(request):
++++month_end+=+MonthEnd.objects.get(file_criteria=criteria)

++++response+=+HttpResponse(month_end.report,+content_type='text/plain')
++++response['Content-Disposition']+=+'attachment;+filename=report.csv'

++++return+response|code-block|syntax|javascript|774470|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Accepted answer is certainly a good solution, but here is the way I went about generating a CSV and serving it from a view.

Thought it was worth while putting this here as it took me a little bit of fiddling to get all the desirable behaviour (overwrite existing file, storing to the right spot, not creating duplicate files etc).

Django 1.4.1

Python 2.7.3

<pre><code>#Model
class MonthEnd(models.Model):
 report = models.FileField(db_index=True, upload_to='not_used')

import csv
from os.path import join

#build and store the file
def write_csv():
 path = join(settings.MEDIA_ROOT, 'files', 'month_end', 'report.csv')
 f = open(path, "w+b")

 #wipe the existing content
 f.truncate()

 csv_writer = csv.writer(f)
 csv_writer.writerow(('col1'))

 for num in range(3):
 csv_writer.writerow((num, ))

 month_end_file = MonthEnd()
 month_end_file.report.name = path
 month_end_file.save()

from my_app.models import MonthEnd

#serve it up as a download
def get_report(request):
 month_end = MonthEnd.objects.get(file_criteria=criteria)

 response = HttpResponse(month_end.report, content_type='text/plain')
 response['Content-Disposition'] = 'attachment; filename=report.csv'

 return response
</code></pre>

blocks|key|558146|text|最好使用上下文管理器，或者在文件保存过程中出现异常的情况下调用close()。如果您的存储后端停机，则可能发生这种情况，等等。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|558147|任何覆盖行为都应该在您的存储后端进行配置。例如，S3Boto3Storage有一个设置AWS_S3_FILE_OVERWRITE。如果你使用的是FileSystemStorage，你可以写一个custom+mixin。|558148|如果您希望发生任何自定义的副作用，比如上次更新的时间戳，您可能还希望调用模型的save方法，而不是FileField的save方法。如果是这样的话，您还可以将文件的名称属性设置为文件的名称-这是相对于MEDIA_ROOT的。它缺省为文件的完整路径，如果不设置它，可能会导致问题-请参阅File.__init__()和File.name。|558149|下面是一个示例，其中self是模型实例，my_file是FileField+/+ImageFile，在整个模型实例上调用save()，而不仅仅是FileField：|558150|import+os
from+django.core.files+import+File

with+open(filepath,+'rb')+as+fi:
++++self.my_file+=+File(fi,+name=os.path.basename(fi.name))
++++self.save()|code-block|syntax|javascript|558151|entityMap|0|LINK|mutability|MUTABLE|url|https://django-storages.readthedocs.io/en/latest/backends/amazon-S3.html|1|https://timonweb.com/posts/imagefield-overwrite-file-if-file-with-the-same-name-exists/|2|https://docs.djangoproject.com/en/2.2/ref/settings/#media-root|3|https://docs.djangoproject.com/en/2.2/_modules/django/core/files/base/#File|4|https://docs.djangoproject.com/en/2.2/ref/files/file/#django.core.files.File.name^0|V|7|0|17|L|20|H|17|L|0|2O|C|1|0|2S|A|2S|A|2|3Y|F|3|4E|9|4|0|A|4|K|7|1O|6|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@$9|17|A|18|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]]|D|@$9|1E|A|1F|1|1G]|$9|1H|A|1I|1|1J]]|E|$]]|$1|H|3|I|5|6|7|1K|8|@$9|1L|A|1M|B|C]]|D|@$9|1N|A|1O|1|1P]|$9|1Q|A|1R|1|1S]|$9|1T|A|1U|1|1V]]|E|$]]|$1|J|3|K|5|6|7|1W|8|@$9|1X|A|1Y|B|C]|$9|1Z|A|20|B|C]|$9|21|A|22|B|C]]|D|@]|E|$]]|$1|L|3|M|5|N|7|23|8|@]|D|@]|E|$O|P]]|$1|Q|3|-4|5|6|7|24|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]|Y|$5|T|U|V|E|$W|Z]]|10|$5|T|U|V|E|$W|11]]|12|$5|T|U|V|E|$W|13]]|14|$5|T|U|V|E|$W|15]]]]

It's good practice to use a context manager or call <code>close()</code> in case of exceptions during the file saving process. Could happen if your storage backend is down, etc.

Any overwrite behavior should be configured in your storage backend. For example S3Boto3Storage has a setting <a href="https://django-storages.readthedocs.io/en/latest/backends/amazon-S3.html" rel="noreferrer"><code>AWS_S3_FILE_OVERWRITE</code></a>. If you're using <code>FileSystemStorage</code> you can write a <a href="https://timonweb.com/posts/imagefield-overwrite-file-if-file-with-the-same-name-exists/" rel="noreferrer">custom mixin</a>.

You might also want to call the model's save method instead of the FileField's save method if you want any custom side-effects to happen, like last-updated timestamps. If that's the case, you can also set the name attribute of the file to the name of the file - which is relative to <a href="https://docs.djangoproject.com/en/2.2/ref/settings/#media-root" rel="noreferrer"><code>MEDIA_ROOT</code></a>. It defaults to the full path of the file which can cause problems if you don't set it - see <a href="https://docs.djangoproject.com/en/2.2/_modules/django/core/files/base/#File" rel="noreferrer">File.__init__()</a> and <a href="https://docs.djangoproject.com/en/2.2/ref/files/file/#django.core.files.File.name" rel="noreferrer">File.name</a>.

Here's an example where <code>self</code> is the model instance where <code>my_file</code> is the FileField / ImageFile, calling <code>save()</code> on the whole model instance instead of just FileField:

<pre><code>import os
from django.core.files import File

with open(filepath, 'rb') as fi:
 self.my_file = File(fi, name=os.path.basename(fi.name))
 self.save()
</code></pre>

Here's my model. What I want to do is generate a new file and overwrite the existing one whenever a model instance is saved:

<pre><code>class Kitten(models.Model):
 claw_size = ...
 license_file = models.FileField(blank=True, upload_to='license')

 def save(self, *args, **kwargs):
 #Generate a new license file overwriting any previous version
 #and update file path
 self.license_file = ???
 super(Request,self).save(*args, **kwargs)
</code></pre>

I see lots of documentation about how to upload a file. But how do I generate a file, assign it to a model field and have Django store it in the right place?

Django - how to create a file and save it to a model's FileField?

Django

Python

这是我的模型。我想要做的是生成一个新文件，并在保存模型实例时覆盖现有文件：class Kitten(models.Model):    claw_size = ...    license_file = models.FileField(blank=True, upload_to='license')    def s...

问Django -如何创建文件并保存到模型的FileField？
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