351 lines
11 KiB
Python
351 lines
11 KiB
Python
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"""link helpers."""
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from typing import Any, Dict, List, Optional
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from urllib.parse import ParseResult, parse_qs, unquote, urlencode, urljoin, urlparse
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import attr
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from stac_fastapi.types.requests import get_base_url
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from stac_pydantic.links import Relations
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from stac_pydantic.shared import MimeTypes
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from starlette.requests import Request
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# These can be inferred from the item/collection so they aren't included in the database
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# Instead they are dynamically generated when querying the database using the classes defined below
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INFERRED_LINK_RELS = ["self", "item", "parent", "collection", "root"]
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def filter_links(links: List[Dict]) -> List[Dict]:
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"""Remove inferred links."""
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return [link for link in links if link["rel"] not in INFERRED_LINK_RELS]
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def merge_params(url: str, newparams: Dict) -> str:
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"""Merge url parameters."""
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u = urlparse(url)
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params = parse_qs(u.query)
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params.update(newparams)
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param_string = unquote(urlencode(params, True))
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href = ParseResult(
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scheme=u.scheme,
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netloc=u.netloc,
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path=u.path,
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params=u.params,
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query=param_string,
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fragment=u.fragment,
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).geturl()
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return href
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@attr.s
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class BaseLinks:
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"""Create inferred links common to collections and items."""
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request: Request = attr.ib()
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@property
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def base_url(self):
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"""Get the base url."""
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return get_base_url(self.request)
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@property
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def url(self):
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"""Get the current request url."""
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base_url = self.request.base_url
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path = self.request.url.path
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# root path can be set in the request scope in two different ways:
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# - by uvicorn when running with --root-path
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# - by FastAPI when running with FastAPI(root_path="...")
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#
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# When root path is set by uvicorn, request.url.path will have the root path prefix.
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# eg. if root path is "/api" and the path is "/collections",
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# the request.url.path will be "/api/collections"
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#
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# We need to remove the root path prefix from the path before
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# joining the base_url and path to get the full url to avoid
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# having root_path twice in the url
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if (
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root_path := self.request.scope.get("root_path")
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) and not self.request.app.root_path:
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# self.request.app.root_path is set by FastAPI when running with FastAPI(root_path="...")
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# If self.request.app.root_path is not set but self.request.scope.get("root_path") is set,
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# then the root path is set by uvicorn
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# So we need to remove the root path prefix from the path before
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# joining the base_url and path to get the full url
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if path.startswith(root_path):
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path = path[len(root_path) :]
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url = urljoin(str(base_url), path.lstrip("/"))
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if qs := self.request.url.query:
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url += f"?{qs}"
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return url
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def resolve(self, url):
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"""Resolve url to the current request url."""
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return urljoin(str(self.base_url), str(url))
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def link_self(self) -> Dict:
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"""Return the self link."""
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return {
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"rel": Relations.self.value,
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"type": MimeTypes.json.value,
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"href": self.url,
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}
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def link_root(self) -> Dict:
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"""Return the catalog root."""
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return {
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"rel": Relations.root.value,
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"type": MimeTypes.json.value,
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"href": self.base_url,
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}
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def create_links(self) -> List[Dict[str, Any]]:
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"""Return all inferred links."""
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links = []
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for name in dir(self):
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if name.startswith("link_") and callable(getattr(self, name)):
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link = getattr(self, name)()
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if link is not None:
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links.append(link)
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return links
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async def get_links(
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self, extra_links: Optional[List[Dict[str, Any]]] = None
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) -> List[Dict[str, Any]]:
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"""
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Generate all the links.
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Get the links object for a stac resource by iterating through
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available methods on this class that start with link_.
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"""
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# TODO: Pass request.json() into function so this doesn't need to be coroutine
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if self.request.method == "POST":
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self.request.postbody = await self.request.json()
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# join passed in links with generated links
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# and update relative paths
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links = self.create_links()
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if extra_links:
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# For extra links passed in,
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# add links modified with a resolved href.
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# Drop any links that are dynamically
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# determined by the server (e.g. self, parent, etc.)
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# Resolving the href allows for relative paths
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# to be stored in pgstac and for the hrefs in the
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# links of response STAC objects to be resolved
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# to the request url.
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links += [
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{**link, "href": self.resolve(link["href"])}
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for link in extra_links
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if link["rel"] not in INFERRED_LINK_RELS
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]
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return links
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@attr.s
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class PagingLinks(BaseLinks):
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"""Create links for paging."""
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next: Optional[str] = attr.ib(kw_only=True, default=None)
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prev: Optional[str] = attr.ib(kw_only=True, default=None)
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def link_next(self) -> Optional[Dict[str, Any]]:
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"""Create link for next page."""
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if self.next is not None:
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method = self.request.method
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if method == "GET":
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href = merge_params(self.url, {"token": f"next:{self.next}"})
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link = {
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"rel": Relations.next.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": href,
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}
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return link
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if method == "POST":
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return {
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"rel": Relations.next.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": self.url,
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"body": {**self.request.postbody, "token": f"next:{self.next}"},
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}
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return None
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def link_prev(self) -> Optional[Dict[str, Any]]:
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"""Create link for previous page."""
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if self.prev is not None:
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method = self.request.method
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if method == "GET":
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href = merge_params(self.url, {"token": f"prev:{self.prev}"})
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return {
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"rel": Relations.previous.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": href,
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}
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if method == "POST":
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return {
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"rel": Relations.previous.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": self.url,
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"body": {**self.request.postbody, "token": f"prev:{self.prev}"},
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}
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return None
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@attr.s
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class CollectionSearchPagingLinks(BaseLinks):
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next: Optional[Dict[str, Any]] = attr.ib(kw_only=True, default=None)
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prev: Optional[Dict[str, Any]] = attr.ib(kw_only=True, default=None)
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def link_next(self) -> Optional[Dict[str, Any]]:
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"""Create link for next page."""
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if self.next is not None:
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method = self.request.method
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if method == "GET":
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# if offset is equal to default value (0), drop it
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if self.next["body"].get("offset", -1) == 0:
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_ = self.next["body"].pop("offset")
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href = merge_params(self.url, self.next["body"])
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# if next link is equal to this link, skip it
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if href == self.url:
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return None
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return {
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"rel": Relations.next.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": href,
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}
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return None
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def link_prev(self):
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if self.prev is not None:
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method = self.request.method
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if method == "GET":
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href = merge_params(self.url, self.prev["body"])
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# if prev link is equal to this link, skip it
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if href == self.url:
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return None
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return {
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"rel": Relations.previous.value,
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"type": MimeTypes.geojson.value,
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"method": method,
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"href": href,
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}
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return None
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@attr.s
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class CollectionLinksBase(BaseLinks):
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"""Create inferred links specific to collections."""
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collection_id: str = attr.ib()
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def collection_link(self, rel: str = Relations.collection.value) -> Dict:
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"""Create a link to a collection."""
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return {
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"rel": rel,
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"type": MimeTypes.json.value,
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"href": self.resolve(f"collections/{self.collection_id}"),
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}
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@attr.s
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class CollectionLinks(CollectionLinksBase):
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"""Create inferred links specific to collections."""
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def link_self(self) -> Dict:
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"""Return the self link."""
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return self.collection_link(rel=Relations.self.value)
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def link_parent(self) -> Dict:
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"""Create the `parent` link."""
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return {
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"rel": Relations.parent.value,
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"type": MimeTypes.json.value,
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"href": self.base_url,
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}
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def link_items(self) -> Dict:
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"""Create the `item` link."""
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return {
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"rel": "items",
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"type": MimeTypes.geojson.value,
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"href": self.resolve(f"collections/{self.collection_id}/items"),
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}
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@attr.s
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class SearchLinks(BaseLinks):
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"""Create inferred links specific to collections."""
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def link_self(self) -> Dict:
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"""Return the self link."""
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return {
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"rel": Relations.self.value,
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"type": MimeTypes.geojson.value,
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"href": self.resolve("search"),
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}
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@attr.s
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class ItemCollectionLinks(CollectionLinksBase):
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"""Create inferred links specific to collections."""
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def link_self(self) -> Dict:
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"""Return the self link."""
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return {
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"rel": Relations.self.value,
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"type": MimeTypes.geojson.value,
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"href": self.resolve(f"collections/{self.collection_id}/items"),
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}
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def link_parent(self) -> Dict:
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"""Create the `parent` link."""
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return self.collection_link(rel=Relations.parent.value)
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def link_collection(self) -> Dict:
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"""Create the `collection` link."""
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return self.collection_link()
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@attr.s
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class ItemLinks(CollectionLinksBase):
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"""Create inferred links specific to items."""
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item_id: str = attr.ib()
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def link_self(self) -> Dict:
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"""Create the self link."""
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return {
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"rel": Relations.self.value,
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"type": MimeTypes.geojson.value,
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"href": self.resolve(
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f"collections/{self.collection_id}/items/{self.item_id}"
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),
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}
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def link_parent(self) -> Dict:
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"""Create the `parent` link."""
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return self.collection_link(rel=Relations.parent.value)
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def link_collection(self) -> Dict:
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"""Create the `collection` link."""
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return self.collection_link()
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