Django 从内存中提供压缩的 GeoDataFrame shapefile 作为下载

Question

我有一个与 Django GIS 相关的应用程序，用户可以在其中下载 shp 文件。我有 geopandas GeoDataFrame 对象。我可以轻松地将其转换为 zip 文件，然后在用户想要下载时将其读取给用户：

from django.http import HttpResponse
import geopandas as gpd
import shapely
import os
from zipfile import ZipFile
def download_shp_zip(request):
    # just some random polygon
    geometry = shapely.geometry.MultiPolygon([
        shapely.geometry.Polygon([ (0, 0), (0, 1), (1, 1), (1, 0) ]),
        shapely.geometry.Polygon([ (2, 2), (2, 3), (3, 3), (3, 2) ]),
    ])
    # create GeoDataFrame
    gdf = gpd.GeoDataFrame(data={'geometry':geometry}, crs='epsg:4326')
    # some basename to save under
    basename = 'basename'
    #  create folder for this session
    os.mkdir(f"local_folder/{basename}")
    # export gdf to this folder
    gdf.to_file(f"local_folder/{basename}/{basename}.shp")
    # this file now contains many files. just zip them
    zipObj = ZipFile(f"local_folder/{basename}.zip", 'w')
    # zip everything in the folder to the zip
    for file in os.listdir(f"local_folder/{basename}"):
        zipObj.write(f"local_folder/{basename}/{file}")
    # create zip
    zipObj.close()
    # now delete the original files that were zipped
    shutil.rmtree(f"local_folder/{basename}")

    # now we can server the zip file to the user
    filename = f'local_folder/{basename}.zip'
    # check if file exists (just in case)
    try:
        fsock = open(filename, "rb")
    except:
        return HttpResponse(f"File '{basename}' Does Not Exist!",
            content_type='text/plain')
    # create response
    response = HttpResponse(fsock, content_type='application/zip')
    response['Content-Disposition'] = f'attachment; filename={basename}.zip'
    return response
    

此方法有效，但它将文件保存到本地存储，然后提供服务。但是，我想将它们保存到内存中，然后将其提供给用户。我见过人们使用 os.BytesIO 来做类似的事情。我一直在玩，但我无法完全找到任何适合我所寻找的东西。

同样，我有 GeoDataFrame。我想将其转换为 shapefile，然后将其压缩，然后将压缩的文件夹从内存提供给用户，而不将其写入本地存储。

Answer 1

可以使用tempfile创建文件并在服务后立即删除它。所以这不是您正在寻找的答案，但也许仍然有帮助。根据这个答案：

一旦文件处理程序关闭，由 tempfile 创建的任何文件都将被删除。在您的情况下，当您退出 with 语句时。

from django.http import HttpResponse
import geopandas as gpd
import shapely
import os
import tempfile
from zipfile import ZipFile

def download_shp_zip(request):

    # just some random polygon
    geometry = shapely.geometry.MultiPolygon([
        shapely.geometry.Polygon([(0, 0), (0, 1), (1, 1), (1, 0)]),
        shapely.geometry.Polygon([(2, 2), (2, 3), (3, 3), (3, 2)]),
    ])
    # create GeoDataFrame
    gdf = gpd.GeoDataFrame(data={'geometry': geometry}, crs='epsg:4326')

    # some basename to save under
    basename = 'basename'

    # Convert to shapefile and serve it to the user
    with tempfile.TemporaryDirectory() as tmp_dir:

        # Export gdf as shapefile
        gdf.to_file(os.path.join(tmp_dir, f'{basename}.shp'), driver='ESRI Shapefile')

        # Zip the exported files to a single file
        tmp_zip_file_name = f'{basename}.zip'
        tmp_zip_file_path = f"{tmp_dir}/{tmp_zip_file_name}"
        tmp_zip_obj = ZipFile(tmp_zip_file_path, 'w')

        for file in os.listdir(tmp_dir):
            if file != tmp_zip_file_name:
                tmp_zip_obj.write(os.path.join(tmp_dir, file), file)

        tmp_zip_obj.close()

        # Return the file
        with open(tmp_zip_file_path, 'rb') as file:
            response = HttpResponse(file, content_type='application/force-download')
            response['Content-Disposition'] = f'attachment; filename="{tmp_zip_file_name}"'
            return response

另一种选择是在 try-except 块内使用 return 语句，并在 finally 语句中删除文件：

        # Return the zip file as download response and delete it afterwards
        try:
            with open(tmp_zip_file_path, 'rb') as file:
                response = HttpResponse(file, content_type='application/force-download')
                response['Content-Disposition'] = f'attachment; filename="{tmp_zip_file_name}"'
                return response
        finally:
            os.remove(tmp_zip_file_path)

为了获得更好的用户体验，您可以在下载开始之前使用加载 gif。