默认情况下如何转到分页的 Flask-Admin 视图的最后一页.. 不降序排序

Question

在用于数据库表查看/管理的 Python Flask-Admin 中，我需要视图自动打开到分页数据的最后一页。

重要提示：我不能简单地对记录进行降序排序，所以最后一条记录首先显示。

下面是我的简单示例。我希望它从最后一页开始，如图所示。

这里有一些示例代码来重现我的模型：

import os
import os.path as op
from flask import Flask
from flask_sqlalchemy import SQLAlchemy

import flask_admin as admin
from flask_admin.contrib.sqla import ModelView


# Create application
app = Flask(__name__)

# Create dummy secrey key so we can use sessions
app.config['SECRET_KEY'] = '123456790'

# Create in-memory database
app.config['DATABASE_FILE'] = 'sample_db2.sqlite'
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///' + app.config['DATABASE_FILE']
app.config['SQLALCHEMY_ECHO'] = True
db = SQLAlchemy(app)


# Models
class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.Unicode(64))
    email = db.Column(db.Unicode(64))

    def __unicode__(self):
        return self.name


class UserAdmin(ModelView):
    column_searchable_list = ('name', 'email')
    column_editable_list = ('name', 'email')
    column_display_pk = True

    can_set_page_size = True
    # the number of entries to display in the list view
    page_size = 5


# Flask views
@app.route('/')
def index():
    return '<a href="/admin/">Click me to get to Admin!</a>'


admin = admin.Admin(app, 'Example', template_mode='bootstrap3')

# Add views
admin.add_view(UserAdmin(User, db.session))


def build_sample_db():
    """
    Populate a small db with some example entries.
    """

    db.drop_all()
    db.create_all()

    first_names = [
        'Harry', 'Amelia', 'Oliver', 'Jack', 'Isabella', 'Charlie','Sophie', 'Mia',
        'Jacob', 'Thomas', 'Emily', 'Lily', 'Ava', 'Isla', 'Alfie', 'Olivia', 'Jessica',
        'Riley', 'William', 'James', 'Geoffrey', 'Lisa', 'Benjamin', 'Stacey', 'Lucy'
    ]
    last_names = [
        'Brown', 'Smith', 'Patel', 'Jones', 'Williams', 'Johnson', 'Taylor', 'Thomas',
        'Roberts', 'Khan', 'Lewis', 'Jackson', 'Clarke', 'James', 'Phillips', 'Wilson',
        'Ali', 'Mason', 'Mitchell', 'Rose', 'Davis', 'Davies', 'Rodriguez', 'Cox', 'Alexander'
    ]

    for i in range(len(first_names)):
        user = User()
        user.name = first_names[i] + " " + last_names[i]
        user.email = first_names[i].lower() + "@example.com"
        db.session.add(user)

    db.session.commit()
    return


if __name__ == '__main__':

    # Build a sample db on the fly, if one does not exist yet.
    app_dir = op.realpath(os.path.dirname(__file__))
    database_path = op.join(app_dir, app.config['DATABASE_FILE'])
    if not os.path.exists(database_path):
        build_sample_db()

    # Start app
    app.run(debug=True, host='0.0.0.0')

Answer 1

我找到了解决问题的理想方法，覆盖了flask_admin.contrib.sqla.ModelView 类中的index_view() 模板渲染视图方法。

class UserAdmin(ModelView):
    column_searchable_list = ('name', 'email')
    column_editable_list = ('name', 'email')
    column_display_pk = True

    can_set_page_size = True
    # the number of entries to display in the list view
    page_size = 5

    # Now to override the index_view method
    @expose('/')
    def index_view(self):
        """List view overridden to DEFAULT to the last page, 
        if no other request args have been submitted"""

        if self.can_delete:
            delete_form = self.delete_form()
        else:
            delete_form = None

        # Grab parameters from URL
        view_args = self._get_list_extra_args()

        # Map column index to column name
        sort_column = self._get_column_by_idx(view_args.sort)
        if sort_column is not None:
            sort_column = sort_column[0]

        # Get page size
        page_size = view_args.page_size or self.page_size

        #####################################################################
        # Custom functionality to start on the last page instead of the first

        if len(request.args) == 0:
            # Standard request for the first page (no additional args)
            count_query = self.get_count_query() if not self.simple_list_pager else None
            # Calculate number of rows if necessary
            count = count_query.scalar() if count_query else None
            # Calculate number of pages
            if count is not None and page_size:
                num_pages = int(ceil(count / float(page_size)))
                # Change the page to the last page (minus 1 for zero-based counting)
                setattr(view_args, 'page', num_pages - 1)

        # End of custom code. The rest below is from the Flask-Admin package
        ############################################################################

        # Get database data for the view_args.page requested
        count, data = self.get_list(view_args.page, sort_column, view_args.sort_desc,
                                    view_args.search, view_args.filters, page_size=page_size)

        list_forms = {}
        if self.column_editable_list:
            for row in data:
                list_forms[self.get_pk_value(row)] = self.list_form(obj=row)

        # Calculate number of pages
        if count is not None and page_size:
            num_pages = int(ceil(count / float(page_size)))
        elif not page_size:
            num_pages = 0  # hide pager for unlimited page_size
        else:
            num_pages = None  # use simple pager

        # Various URL generation helpers
        def pager_url(p):
            # Do not add page number if it is first page
            if p == 0:
                p = None

            return self._get_list_url(view_args.clone(page=p))

        def sort_url(column, invert=False, desc=None):
            if not desc and invert and not view_args.sort_desc:
                desc = 1

            return self._get_list_url(view_args.clone(sort=column, sort_desc=desc))

        def page_size_url(s):
            if not s:
                s = self.page_size

            return self._get_list_url(view_args.clone(page_size=s))

        # Actions
        actions, actions_confirmation = self.get_actions_list()
        if actions:
            action_form = self.action_form()
        else:
            action_form = None

        clear_search_url = self._get_list_url(view_args.clone(page=0,
                                                              sort=view_args.sort,
                                                              sort_desc=view_args.sort_desc,
                                                              search=None,
                                                              filters=None))

        return self.render(
            self.list_template,
            data=data,
            list_forms=list_forms,
            delete_form=delete_form,
            action_form=action_form,

            # List
            list_columns=self._list_columns,
            sortable_columns=self._sortable_columns,
            editable_columns=self.column_editable_list,
            list_row_actions=self.get_list_row_actions(),

            # Pagination
            count=count,
            pager_url=pager_url,
            num_pages=num_pages,
            can_set_page_size=self.can_set_page_size,
            page_size_url=page_size_url,
            page=view_args.page,
            page_size=page_size,
            default_page_size=self.page_size,

            # Sorting
            sort_column=view_args.sort,
            sort_desc=view_args.sort_desc,
            sort_url=sort_url,

            # Search
            search_supported=self._search_supported,
            clear_search_url=clear_search_url,
            search=view_args.search,
            search_placeholder=self.search_placeholder(),

            # Filters
            filters=self._filters,
            filter_groups=self._get_filter_groups(),
            active_filters=view_args.filters,
            filter_args=self._get_filters(view_args.filters),

            # Actions
            actions=actions,
            actions_confirmation=actions_confirmation,

            # Misc
            enumerate=enumerate,
            get_pk_value=self.get_pk_value,
            get_value=self.get_list_value,
            return_url=self._get_list_url(view_args),

            # Extras
            extra_args=view_args.extra_args,
        )

Answer 2

下面的想法怎么样：

# Flask views
@app.route('/')
def index():
    # from sqlalchemy import func
    # n=(db.session.query(func.count(User.id)).all())[0][0]
    # or
    n=len(User.query.all())
    last_page=int((n-1)/UserAdmin.page_size)
    return f'<a href="/admin/user/?page={last_page}">Click me to get to Admin!</a>'