kopia lustrzana https://github.com/jointakahe/takahe
112 wiersze
3.4 KiB
Python
112 wiersze
3.4 KiB
Python
import dataclasses
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import urllib.parse
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from django.db import models
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from django.http import HttpRequest
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@dataclasses.dataclass
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class PaginationResult:
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#: A list of objects that matched the pagination query.
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results: list[models.Model]
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#: The actual applied limit, which may be different from what was requested.
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limit: int
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sort_attribute: str
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def next(self, request: HttpRequest, allowed_params: list[str]):
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"""
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Returns a URL to the next page of results.
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"""
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if not self.results:
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return None
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params = self.filter_params(request, allowed_params)
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params["max_id"] = self.results[-1].pk
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return f"{request.build_absolute_uri(request.path)}?{urllib.parse.urlencode(params)}"
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def prev(self, request: HttpRequest, allowed_params: list[str]):
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"""
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Returns a URL to the previous page of results.
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"""
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if not self.results:
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return None
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params = self.filter_params(request, allowed_params)
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params["min_id"] = self.results[0].pk
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return f"{request.build_absolute_uri(request.path)}?{urllib.parse.urlencode(params)}"
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@staticmethod
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def filter_params(request: HttpRequest, allowed_params: list[str]):
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params = {}
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for key in allowed_params:
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value = request.GET.get(key, None)
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if value:
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params[key] = value
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return params
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class MastodonPaginator:
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"""
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Paginates in the Mastodon style (max_id, min_id, etc)
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"""
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def __init__(
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self,
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anchor_model: type[models.Model],
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sort_attribute: str = "created",
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default_limit: int = 20,
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max_limit: int = 40,
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):
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self.anchor_model = anchor_model
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self.sort_attribute = sort_attribute
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self.default_limit = default_limit
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self.max_limit = max_limit
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def paginate(
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self,
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queryset,
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min_id: str | None,
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max_id: str | None,
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since_id: str | None,
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limit: int | None,
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):
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if max_id:
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try:
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anchor = self.anchor_model.objects.get(pk=max_id)
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except self.anchor_model.DoesNotExist:
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return []
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queryset = queryset.filter(
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**{self.sort_attribute + "__lt": getattr(anchor, self.sort_attribute)}
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)
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if since_id:
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try:
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anchor = self.anchor_model.objects.get(pk=since_id)
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except self.anchor_model.DoesNotExist:
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return []
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queryset = queryset.filter(
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**{self.sort_attribute + "__gt": getattr(anchor, self.sort_attribute)}
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)
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if min_id:
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# Min ID requires items _immediately_ newer than specified, so we
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# invert the ordering to accommodate
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try:
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anchor = self.anchor_model.objects.get(pk=min_id)
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except self.anchor_model.DoesNotExist:
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return []
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queryset = queryset.filter(
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**{self.sort_attribute + "__gt": getattr(anchor, self.sort_attribute)}
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).order_by(self.sort_attribute)
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else:
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queryset = queryset.order_by("-" + self.sort_attribute)
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limit = min(limit or self.default_limit, self.max_limit)
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return PaginationResult(
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results=list(queryset[:limit]),
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limit=limit,
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sort_attribute=self.sort_attribute,
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)
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