fix: pvforecast fails when there is only a single plane (#569)

* fix: pvforecast fails when there is only a single plane

* fix: formatting

* fix: formatting

* fix: add type annotations

* add testdata and validation test for single plane

* fix: formatting

src/akkudoktoreos/prediction/pvforecastakkudoktor.py

@@ -78,7 +78,7 @@ Methods:
 from typing import Any, List, Optional, Union
 
 import requests
-from pydantic import Field, ValidationError, computed_field
+from pydantic import Field, ValidationError, computed_field, field_validator
 
 from akkudoktoreos.core.cache import cache_in_file
 from akkudoktoreos.core.logging import get_logger
@@ -114,6 +114,30 @@ class AkkudoktorForecastMeta(PydanticBaseModel):
     horizont: List[List[AkkudoktorForecastHorizon]]
     horizontString: List[str]
 
+    @field_validator("power", "azimuth", "tilt", "powerInverter", mode="before")
+    @classmethod
+    def ensure_list(cls, v: Any) -> List[int]:
+        return v if isinstance(v, list) else [v]
+
+    @field_validator("horizont", mode="before")
+    @classmethod
+    def normalize_horizont(cls, v: Any) -> List[List[AkkudoktorForecastHorizon]]:
+        if isinstance(v, list):
+            # Case: flat list of dicts
+            if v and isinstance(v[0], dict):
+                return [v]
+            # Already in correct nested form
+            if v and isinstance(v[0], list):
+                return v
+        return v
+
+    @field_validator("horizontString", mode="before")
+    @classmethod
+    def parse_horizont_string(cls, v: Any) -> List[str]:
+        if isinstance(v, str):
+            return [s.strip() for s in v.split(",")]
+        return v
+
 
 class AkkudoktorForecastValue(PydanticBaseModel):
     datetime: str

tests/test_pvforecastakkudoktor.py

@@ -19,6 +19,9 @@ from akkudoktoreos.utils.datetimeutil import compare_datetimes, to_datetime, to_
 DIR_TESTDATA = Path(__file__).absolute().parent.joinpath("testdata")
 
 FILE_TESTDATA_PV_FORECAST_INPUT_1 = DIR_TESTDATA.joinpath("pv_forecast_input_1.json")
+FILE_TESTDATA_PV_FORECAST_INPUT_SINGLE_PLANE = DIR_TESTDATA.joinpath(
+    "pv_forecast_input_single_plane.json"
+)
 FILE_TESTDATA_PV_FORECAST_RESULT_1 = DIR_TESTDATA.joinpath("pv_forecast_result_1.txt")
 
 logger = get_logger(__name__)
@@ -93,6 +96,16 @@ def sample_forecast_data_raw():
     return input_data
 
 
+@pytest.fixture
+def sample_forecast_data_single_plane_raw():
+    """Fixture that returns raw sample forecast data."""
+    with FILE_TESTDATA_PV_FORECAST_INPUT_SINGLE_PLANE.open(
+        "r", encoding="utf-8", newline=None
+    ) as f_in:
+        input_data = f_in.read()
+    return input_data
+
+
 @pytest.fixture
 def sample_forecast_report():
     """Fixture that returns sample forecast data report."""
@@ -236,6 +249,20 @@ def test_pvforecast_akkudoktor_validate_data(provider_empty_instance, sample_for
     # everything worked
 
 
+def test_pvforecast_akkudoktor_validate_data_single_plane(
+    provider_empty_instance, sample_forecast_data_single_plane_raw
+):
+    """Test validation of PV forecast data on sample data with a single plane."""
+    logger.info("The following errors are intentional and part of the test.")
+    with pytest.raises(
+        ValueError,
+        match="Field: meta\nError: Field required\nType: missing\nField: values\nError: Field required\nType: missing\n",
+    ):
+        ret = provider_empty_instance._validate_data("{}")
+    data = provider_empty_instance._validate_data(sample_forecast_data_single_plane_raw)
+    # everything worked
+
+
 @patch("requests.get")
 def test_pvforecast_akkudoktor_update_with_sample_forecast(
     mock_get, sample_settings, sample_forecast_data_raw, sample_forecast_start, provider