Python elasticsearch-dsl django 分页

Question

我如何在 elasticsearch dsl 上使用 django 分页。 我的代码：

query = MultiMatch(query=q, fields=['title', 'body'], fuzziness='AUTO')

s = Search(using=elastic_client, index='post').query(query).sort('-created_at')
response = s.execute()

// this always returns page count 1
paginator = Paginator(response, 100)
page = request.GET.get('page')
try:
    posts = paginator.page(page)
except PageNotAnInteger:
    posts = paginator.page(1)
except EmptyPage:
    posts = paginator.page(paginator.num_pages)

有什么解决办法吗？

Answer 1

我在 link 上找到了这个分页器：

from django.core.paginator import Paginator, Page

class DSEPaginator(Paginator):
    """
    Override Django's built-in Paginator class to take in a count/total number of items;
    Elasticsearch provides the total as a part of the query results, so we can minimize hits.
    """
    def __init__(self, *args, **kwargs):
        super(DSEPaginator, self).__init__(*args, **kwargs)
        self._count = self.object_list.hits.total

    def page(self, number):
        # this is overridden to prevent any slicing of the object_list - Elasticsearch has
        # returned the sliced data already.
        number = self.validate_number(number)
        return Page(self.object_list, number, self)

然后在视图中我使用：

    q = request.GET.get('q', None)
    page = int(request.GET.get('page', '1'))
    start = (page-1) * 10
    end = start + 10

    query = MultiMatch(query=q, fields=['title', 'body'], fuzziness='AUTO')
    s = Search(using=elastic_client, index='post').query(query)[start:end]
    response = s.execute()

    paginator = DSEPaginator(response, settings.POSTS_PER_PAGE)
    try:
        posts = paginator.page(page)
    except PageNotAnInteger:
        posts = paginator.page(1)
    except EmptyPage:
        posts = paginator.page(paginator.num_pages)

这样可以完美运行..

Answer 2

根据 Danielle Madeley 的建议，我还创建了一个搜索结果代理，该代理与最新版本的 django-elasticsearch-dsl==0.4.4 配合使用。

from django.utils.functional import LazyObject

class SearchResults(LazyObject):
    def __init__(self, search_object):
        self._wrapped = search_object

    def __len__(self):
        return self._wrapped.count()

    def __getitem__(self, index):
        search_results = self._wrapped[index]
        if isinstance(index, slice):
            search_results = list(search_results)
        return search_results

然后您可以像这样在搜索视图中使用它：

paginate_by = 20
search = MyModelDocument.search()
# ... do some filtering ...
search_results = SearchResults(search)

paginator = Paginator(search_results, paginate_by)
page_number = request.GET.get("page")
try:
    page = paginator.page(page_number)
except PageNotAnInteger:
    # If page parameter is not an integer, show first page.
    page = paginator.page(1)
except EmptyPage:
    # If page parameter is out of range, show last existing page.
    page = paginator.page(paginator.num_pages)

Django 的 LazyObject 代理来自分配给 _wrapped 属性的对象的所有属性和方法。我覆盖了 Django 分页器所需的几个方法，但不能与 Search() 实例一起使用。

Answer 3

一个非常简单的解决方案是使用MultipleObjectMixin 并通过覆盖它来提取get_queryset() 中的弹性结果。在这种情况下，如果您添加 paginate_by 属性，Django 将自行处理分页。

应该是这样的：

class MyView(MultipleObjectMixin, ListView):
    paginate_by = 10

    def get_queryset(self):
        object_list = []
        """ Query Elastic here and return the response data in `object_list`.
            If you wish to add filters when querying Elastic,
            you can use self.request.GET params here. """
        return object_list

注意：上面的代码很宽泛，与我自己的情况不同，所以我不能保证它有效。我通过继承其他 Mixins、覆盖 get_queryset() 并利用 Django 的内置分页来使用类似的解决方案 - 它对我来说非常有用。由于这是一个简单的修复，我决定在这里发布一个类似的示例。

Answer 4

另一种方法是在 Paginator 和 Elasticsearch 查询之间创建一个代理。 Paginator 需要两件事，__len__（或count）和__getitem__（需要切片）。代理的粗略版本如下所示：

class ResultsProxy(object):
    """
    A proxy object for returning Elasticsearch results that is able to be
    passed to a Paginator.
    """

    def __init__(self, es, index=None, body=None):
        self.es = es
        self.index = index
        self.body = body

    def __len__(self):
        result = self.es.count(index=self.index,
                               body=self.body)
        return result['count']

    def __getitem__(self, item):
        assert isinstance(item, slice)

        results = self.es.search(
            index=self.index,
            body=self.body,
            from_=item.start,
            size=item.stop - item.start,
        )

        return results['hits']['hits']

可以将代理实例传递给Paginator，并根据需要向 ES 发出请求。