python - 将 django-import-export 与基于类的 View 一起使用

Question

我想将 django-import-export 与基于类的 View 一起使用。

在 https://django-import-export.readthedocs.org/en/latest/getting_started.html 的文档中我看到一个导出为 csv 的示例

>>> dataset = BookResource().export()
>>> print dataset.csv
id,name,author,author_email,imported,published,price,categories
2,Some book,1,,0,2012-12-05,8.85,1

但是如果我想返回一个 Excel 文件，我应该使用哪个基于类的 View 呢？只是查看？

Answer 1

果酱，

基于 https://github.com/bmihelac/django-import-export 的实现并以具有名称和缩写属性的模型“国家/地区”为例:

首先，在国家模型文件的末尾定义资源:

class CountryResource(resources.ModelResource):
    class Meta:
        model = Country

然后，实现基于类的 View :

class CountryExport(View):

    def get(self, *args, **kwargs ):
        dataset = CountryResource().export()
        response = HttpResponse(dataset.csv, content_type="csv")
        response['Content-Disposition'] = 'attachment; filename=filename.csv'
        return response


class CountryImport(View):
    model = Country
    from_encoding = "utf-8"

    #: import / export formats
    DEFAULT_FORMATS = (
        base_formats.CSV,
        base_formats.XLS,
        base_formats.TSV,
        base_formats.ODS,
        base_formats.JSON,
        base_formats.YAML,
        base_formats.HTML,
    )
    formats = DEFAULT_FORMATS
    #: template for import view
    import_template_name = 'Country/import.html'
    resource_class = None

    def get_import_formats(self):
        """
        Returns available import formats.
        """
        return [f for f in self.formats if f().can_import()]

    def get_resource_class(self):
        if not self.resource_class:
            return modelresource_factory(self.model)
        else:
            return self.resource_class

    def get_import_resource_class(self):
        """
        Returns ResourceClass to use for import.
        """
        return self.get_resource_class()

    def get(self, *args, **kwargs ):
        '''
        Perform a dry_run of the import to make sure the import will not
        result in errors.  If there where no error, save the user
        uploaded file to a local temp file that will be used by
        'process_import' for the actual import.
        '''
        resource = self.get_import_resource_class()()

        context = {}

        import_formats = self.get_import_formats()
        form = ImportForm(import_formats,
                          self.request.POST or None,
                          self.request.FILES or None)

        if self.request.POST and form.is_valid():
            input_format = import_formats[
                int(form.cleaned_data['input_format'])
            ]()
            import_file = form.cleaned_data['import_file']
            # first always write the uploaded file to disk as it may be a
            # memory file or else based on settings upload handlers
            with tempfile.NamedTemporaryFile(delete=False) as uploaded_file:
                for chunk in import_file.chunks():
                    uploaded_file.write(chunk)

            # then read the file, using the proper format-specific mode
            with open(uploaded_file.name,
                      input_format.get_read_mode()) as uploaded_import_file:
                # warning, big files may exceed memory
                data = uploaded_import_file.read()
                if not input_format.is_binary() and self.from_encoding:
                    data = force_text(data, self.from_encoding)
                dataset = input_format.create_dataset(data)
                result = resource.import_data(dataset, dry_run=True,
                                              raise_errors=False)

            context['result'] = result

            if not result.has_errors():
                context['confirm_form'] = ConfirmImportForm(initial={
                    'import_file_name': os.path.basename(uploaded_file.name),
                    'input_format': form.cleaned_data['input_format'],
                })

        context['form'] = form
        context['opts'] = self.model._meta
        context['fields'] = [f.column_name for f in resource.get_fields()]

        return TemplateResponse(self.request, [self.import_template_name], context)


    def post(self, *args, **kwargs ):
        '''
        Perform a dry_run of the import to make sure the import will not
        result in errors.  If there where no error, save the user
        uploaded file to a local temp file that will be used by
        'process_import' for the actual import.
        '''
        resource = self.get_import_resource_class()()

        context = {}

        import_formats = self.get_import_formats()
        form = ImportForm(import_formats,
                          self.request.POST or None,
                          self.request.FILES or None)

        if self.request.POST and form.is_valid():
            input_format = import_formats[
                int(form.cleaned_data['input_format'])
            ]()
            import_file = form.cleaned_data['import_file']
            # first always write the uploaded file to disk as it may be a
            # memory file or else based on settings upload handlers
            with tempfile.NamedTemporaryFile(delete=False) as uploaded_file:
                for chunk in import_file.chunks():
                    uploaded_file.write(chunk)

            # then read the file, using the proper format-specific mode
            with open(uploaded_file.name,
                      input_format.get_read_mode()) as uploaded_import_file:
                # warning, big files may exceed memory
                data = uploaded_import_file.read()
                if not input_format.is_binary() and self.from_encoding:
                    data = force_text(data, self.from_encoding)
                dataset = input_format.create_dataset(data)
                result = resource.import_data(dataset, dry_run=True,
                                              raise_errors=False)

            context['result'] = result

            if not result.has_errors():
                context['confirm_form'] = ConfirmImportForm(initial={
                    'import_file_name': os.path.basename(uploaded_file.name),
                    'input_format': form.cleaned_data['input_format'],
                })

        context['form'] = form
        context['opts'] = self.model._meta
        context['fields'] = [f.column_name for f in resource.get_fields()]

        return TemplateResponse(self.request, [self.import_template_name], context)

class CountryProcessImport(View):
    model = Country
    from_encoding = "utf-8"

    #: import / export formats
    DEFAULT_FORMATS = (
        base_formats.CSV,
        base_formats.XLS,
        base_formats.TSV,
        base_formats.ODS,
        base_formats.JSON,
        base_formats.YAML,
        base_formats.HTML,
    )
    formats = DEFAULT_FORMATS
    #: template for import view
    import_template_name = 'Country/import.html'
    resource_class = None



    def get_import_formats(self):
        """
        Returns available import formats.
        """
        return [f for f in self.formats if f().can_import()]

    def get_resource_class(self):
        if not self.resource_class:
            return modelresource_factory(self.model)
        else:
            return self.resource_class

    def get_import_resource_class(self):
        """
        Returns ResourceClass to use for import.
        """
        return self.get_resource_class()

    def post(self, *args, **kwargs ):
        '''
        Perform the actual import action (after the user has confirmed he
    wishes to import)
        '''
        opts = self.model._meta
        resource = self.get_import_resource_class()()

        confirm_form = ConfirmImportForm(self.request.POST)
        if confirm_form.is_valid():
            import_formats = self.get_import_formats()
            input_format = import_formats[
                int(confirm_form.cleaned_data['input_format'])
            ]()
            import_file_name = os.path.join(
                tempfile.gettempdir(),
                confirm_form.cleaned_data['import_file_name']
            )
            import_file = open(import_file_name, input_format.get_read_mode())
            data = import_file.read()
            if not input_format.is_binary() and self.from_encoding:
                data = force_text(data, self.from_encoding)
            dataset = input_format.create_dataset(data)

            result = resource.import_data(dataset, dry_run=False,
                                 raise_errors=True)

            # Add imported objects to LogEntry
            ADDITION = 1
            CHANGE = 2
            DELETION = 3
            logentry_map = {
                RowResult.IMPORT_TYPE_NEW: ADDITION,
                RowResult.IMPORT_TYPE_UPDATE: CHANGE,
                RowResult.IMPORT_TYPE_DELETE: DELETION,
            }
            content_type_id=ContentType.objects.get_for_model(self.model).pk
            '''
            for row in result:
                LogEntry.objects.log_action(
                    user_id=request.user.pk,
                    content_type_id=content_type_id,
                    object_id=row.object_id,
                    object_repr=row.object_repr,
                    action_flag=logentry_map[row.import_type],
                    change_message="%s through import_export" % row.import_type,
                )
            '''
            success_message = _('Import finished')
            messages.success(self.request, success_message)
            import_file.close()

            url = reverse('%s_list' % (str(opts.app_label).lower()))
            return HttpResponseRedirect(url)

模板 import.html 具有以下代码:

<h1>{% trans "Importar" %} {{ opts.app_label }}</h1>

{% if confirm_form %}
  <form action="{% url "process_import" %}" method="POST">
    {% csrf_token %}
    {{ confirm_form.as_p }}
    <p>
      {% trans "Below is a preview of data to be imported. If you are satisfied with the results, click 'Confirm import'" %}
    </p>
    <div class="submit-row">
      <input type="submit" class="btn" name="confirm" value="{% trans "Confirm import" %}">
    </div>
  </form>

{% else %}
  <form action="{{ form_url }}" method="post" id="{{ opts.module_name }}_form" enctype="multipart/form-data">
    {% csrf_token %}

    <p>
      {% trans "This importer will import the following fields: " %}
      {% for f in fields  %}
        {% if forloop.counter0 %}
        , 
        {% endif %}
        <tt>{{ f }}</tt>
      {% endfor %}
    </p>

    <fieldset class="module aligned">
      {% for field in form %}
        <div class="form-row">
          {{ field.errors }}

          {{ field.label_tag }}

          {{ field }}

          {% if field.field.help_text %}
          <p class="help">{{ field.field.help_text|safe }}</p>
          {% endif %}
        </div>
      {% endfor %}
    </fieldset>

    <div class="submit-row">
      <input type="submit" class="btn" value="{% trans "Submit" %}">
    </div>
  </form>
{% endif %}

{% if result %}
    {% if result.has_errors %}
        <h2>{% trans "Errors" %}</h2>
        <ul>
            {% for error in result.base_errors  %}
                <li>{{ error.error }}</li>
            {% endfor %}
            {% for line, errors in result.row_errors %}
                {% for error in errors %}
                    <li>
                      {% trans "Line number" %}: {{ line }} - {{ error.error }}
                      <div class="traceback">{{ error.traceback|linebreaks }}</div>
                    </li>
                {% endfor %}
            {% endfor %}
        </ul>
    {% else %}
        <h2>
            {% trans "Preview" %}
        </h2>
        <table>
        <thead>
          <tr>
            <th></th>
            {% for field in fields %}
              <th>{{ field }}</th>
            {% endfor %}
          </tr>
        </thead>
        {% for row in result.rows %}
            <tr>
                <td>
                {% if row.import_type == 'new' %}
                    {% trans "New" %}
                {% elif row.import_type == 'skip' %}
                    {% trans "Skipped" %}
                {% elif row.import_type == 'delete' %}
                    {% trans "Delete" %}
                {% elif row.import_type == 'update' %}
                    {% trans "Update" %}
                {% endif %}
                </td>
              {% for field in row.diff %}
              <td>
                  {{ field }}
              </td>
              {% endfor %}
            </tr>
        {% endfor %}
        </table>
    {% endif %}
{% endif %}

并且 urls.py 应该包含:

#export
url(r'export/$', login_required(CountryExport.as_view()), name='country_export'),

#import
url(r'import/$', login_required(CountryImport.as_view()), name='country_import'),
url(r'process_import/$',     login_required(CountryProcessImport.as_view()), name='process_import'),