Add download api (CSV)

src/gisaf/api/download.py

@@ -0,0 +1,77 @@
+import logging
+import io
+from typing import Annotated
+
+from fastapi import (Depends, APIRouter, HTTPException, status, Response)
+from fastapi.responses import FileResponse, StreamingResponse
+from sqlmodel import select
+from sqlalchemy.orm import selectinload, joinedload
+
+from gisaf.database import pandas_query, fastapi_db_session as db_session
+from gisaf.models.geo_models_base import GeoModel, PlottableModel
+from gisaf.security import (
+    Token, authenticate_user, get_current_active_user, create_access_token,
+    )
+from gisaf.models.authentication import (User, UserRead, Role, RoleRead)
+from gisaf.registry import registry, NotInRegistry
+
+logger = logging.getLogger(__name__)
+
+api = APIRouter(
+    tags=["download"],
+    # dependencies=[Depends(get_token_header)],
+    responses={404: {"description": "Not found"}},
+)
+
+@api.get('/csv/{store}/{model_id}/{value}/{resample}',
+         responses={
+             200: {
+                 "content": {
+                     "text/csv": {}
+                 }
+             }
+         })
+async def download_csv(
+    store: str, model_id: int, value: str, resample: str,
+    db_session: db_session,
+    user: Annotated[UserRead, Depends(get_current_active_user)]
+    ) -> StreamingResponse:
+    try:
+        store_record = registry.stores.loc[store]
+        model: type[GeoModel] = store_record.model
+        values_model = registry.values_for_model[model][0]
+    except KeyError:
+        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND)
+    ## Check if there's a custom getter
+    custom_getter = getattr(values_model, f'get_{value}', None)
+    if custom_getter:
+        df = await custom_getter(model_id)
+    else:
+        df = await values_model.get_as_dataframe(model_id=model_id, with_only_columns=[value])
+    if len(df) == 0:
+        raise HTTPException(status.HTTP_204_NO_CONTENT)
+    if resample and resample != '0':
+        value_defs = [v for v in values_model.values if v['name'] == value]
+        if len(value_defs) > 0 and 'agg' in value_defs[0]:
+            resampling_method = value_defs[0]['agg']
+        else:
+            resampling_method = 'mean'
+        df = df.resample(resample).agg(resampling_method)
+        if len(df) > 0:
+            df.reset_index(inplace=True)
+    query = select(model).where(model.id == model_id).options(
+        *(joinedload(jt) for jt in model.selectinload()))
+    response = await db_session.exec(query)
+    item = response.one()
+    filename = f'"{item.caption}-{value}-{resample}.csv"'
+    filename = f'{item.__class__.__name__}-{value}-{resample}.csv'
+    stream = io.StringIO()
+    df.reset_index().to_csv(stream,
+                            index=False,
+                            date_format='%d/%m/%Y %H:%M',
+                            float_format=values_model.float_format)
+    response = Response(stream.getvalue(),
+                                 headers={
+                                    'Content-Disposition': f"attachment; filename={filename}"
+                                 })
+    return response