Enh/motor thrustcurve api

docs/user/motors/genericmotor.rst

@@ -106,3 +106,83 @@ note that the user can still provide the parameters manually if needed.
   The ``load_from_eng_file`` method is a very useful tool for simulating motors \
   when the user does not have all the information required to build a ``SolidMotor`` yet.
 
+The ``load_from_thrustcurve_api`` method
+---------------------------------------
+
+The ``GenericMotor`` class provides a convenience loader that downloads a temporary
+`.eng` file from the ThrustCurve.org public API and builds a ``GenericMotor``
+instance from it. This is useful when you know a motor designation (for example
+``"M1670"``) but do not want to manually download and
+save the `.eng` file.
+
+.. note::
+
+    This method performs network requests to the ThrustCurve API. Use it only
+    when you have network access. For automated testing or reproducible runs,
+    prefer using local `.eng` files.
+Signature
+----------
+
+``GenericMotor.load_from_thrustcurve_api(name: str, **kwargs) -> GenericMotor``
+
+Parameters
+----------
+name : str
+    Motor name to search on ThrustCurve (example:
+    ``"M1670"``).Only shorthand names are accepted (e.g. ``"M1670"``, not
+    ``"Cesaroni M1670"``).
+    when multiple matches occur the first result returned by the API is used.
+**kwargs :
+    Same optional arguments accepted by the :class:`GenericMotor` constructor
+    (e.g. ``dry_mass``, ``nozzle_radius``, ``interpolation_method``). Any
+    parameters provided here override values parsed from the downloaded file.
+
+Returns
+----------
+GenericMotor
+    A new ``GenericMotor`` instance created from the .eng data downloaded from
+    ThrustCurve.
+
+Raises
+----------
+ValueError
+    If the API search returns no motor, or if the download endpoint returns no
+    .eng file or empty/invalid data.
+requests.exceptions.RequestException
+
+Behavior notes
+---------------
+- The method first performs a search on ThrustCurve using the provided name.
+  If no results are returned a :class:`ValueError` is raised.
+- If a motor is found the method requests the .eng file in RASP format, decodes
+  it and temporarily writes it to disk; a ``GenericMotor`` is then constructed
+  using the existing .eng file loader. The temporary file is removed even if an
+  error occurs.
+- The function emits a non-fatal informational warning when a motor is found
+  (``warnings.warn(...)``). This follows the repository convention for
+  non-critical messages; callers can filter or suppress warnings as needed.
+
+Example
+---------------
+
+.. jupyter-execute::
+
+    from rocketpy.motors import GenericMotor
+
+    # Build a motor by name (requires network access)
+    motor = GenericMotor.load_from_thrustcurve_api("M1670")
+
+    # Use the motor as usual
+    motor.info()
+
+Testing advice
+---------------
+- ``pytest``'s ``caplog`` or ``capfd`` to assert on log/warning output.
+
+Security & reliability
+----------------
+- The method makes outgoing HTTP requests and decodes base64-encoded content;
+  validate inputs in upstream code if you accept motor names from untrusted
+  sources.
+- Network failures, API rate limits, or changes to the ThrustCurve API may
+  break loading; consider caching downloaded `.eng` files for production use.

rocketpy/motors/motor.py

@@ -1,11 +1,14 @@
+import base64
 import re
+import tempfile
 import warnings
 import xml.etree.ElementTree as ET
 from abc import ABC, abstractmethod
 from functools import cached_property
-from os import path
+from os import path, remove
 
 import numpy as np
+import requests
 
 from ..mathutils.function import Function, funcify_method
 from ..plots.motor_plots import _MotorPlots
@@ -1914,6 +1917,93 @@ def load_from_rse_file(
             coordinate_system_orientation=coordinate_system_orientation,
         )
 
+    @staticmethod
+    def load_from_thrustcurve_api(name: str, **kwargs):
+        """
+        Creates a Motor instance by downloading a .eng file from the ThrustCurve API
+        based on the given motor name.
+
+        Parameters
+        ----------
+        name : str
+            The motor name according to the API (e.g., "Cesaroni_M1670" or "M1670").
+            Both manufacturer-prefixed and shorthand names are commonly used; if multiple
+            motors match the search, the first result is used.
+        **kwargs :
+            Additional arguments passed to the Motor constructor or loader, such as
+            dry_mass, nozzle_radius, etc.
+
+        Returns
+        -------
+        instance : GenericMotor
+            A new GenericMotor instance initialized using the downloaded .eng file.
+
+        Raises
+        ------
+        ValueError
+            If no motor is found or if the downloaded .eng data is missing.
+        requests.exceptions.RequestException
+            If a network or HTTP error occurs during the API call.
+        """
+        base_url = "https://www.thrustcurve.org/api/v1"
+
+        # Step 1. Search motor
+        response = requests.get(f"{base_url}/search.json", params={"commonName": name})
+        response.raise_for_status()
+        data = response.json()
+
+        if not data.get("results"):
+            raise ValueError(
+                f"No motor found for name '{name}'. "
+                "Please verify the motor name format (e.g., 'Cesaroni_M1670' or 'M1670') and try again."
+            )
+
+        motor_info = data["results"][0]
+        motor_id = motor_info.get("motorId")
+        designation = motor_info.get("designation", "").replace("/", "-")
+        manufacturer = motor_info.get("manufacturer", "")
+        warnings.warn(f"Motor found: {designation} ({manufacturer})", UserWarning)
+
+        # Step 2. Download the .eng file
+        dl_response = requests.get(
+            f"{base_url}/download.json",
+            params={"motorIds": motor_id, "format": "RASP", "data": "file"},
+        )
+        dl_response.raise_for_status()
+        dl_data = dl_response.json()
+
+        if not dl_data.get("results"):
+            raise ValueError(
+                f"No .eng file found for motor '{name}' in the ThrustCurve API."
+            )
+
+        data_base64 = dl_data["results"][0].get("data")
+        if not data_base64:
+            raise ValueError(
+                f"Downloaded .eng data for motor '{name}' is empty or invalid."
+            )
+
+        data_bytes = base64.b64decode(data_base64)
+
+        # Step 3. Create the motor from the .eng file
+        tmp_path = None
+        try:
+            # create a temporary file that persists until we explicitly remove it
+            with tempfile.NamedTemporaryFile(suffix=".eng", delete=False) as tmp_file:
+                tmp_file.write(data_bytes)
+                tmp_file.flush()
+                tmp_path = tmp_file.name
+
+            return GenericMotor.load_from_eng_file(tmp_path, **kwargs)
+        finally:
+            # Ensuring the temporary file is removed
+            if tmp_path and path.exists(tmp_path):
+                try:
+                    remove(tmp_path)
+                except OSError:
+                    # If cleanup fails, don't raise: we don't want to mask prior exceptions.
+                    pass
+
     def all_info(self):
         """Prints out all data and graphs available about the Motor."""
         # Print motor details

tests/unit/motors/test_genericmotor.py

@@ -1,5 +1,8 @@
+import base64
+
 import numpy as np
 import pytest
+import requests
 import scipy.integrate
 
 from rocketpy import Function, Motor
@@ -211,3 +214,143 @@ def test_load_from_rse_file(generic_motor):
     assert thrust_curve[0][1] == 0.0  # First thrust point
     assert thrust_curve[-1][0] == 2.2  # Last point of time
     assert thrust_curve[-1][1] == 0.0  # Last thrust point
+
+
+def test_load_from_thrustcurve_api(monkeypatch, generic_motor):
+    """
+    Tests the GenericMotor.load_from_thrustcurve_api method with mocked ThrustCurve API responses.
+    Parameters
+    ----------
+    monkeypatch : pytest.MonkeyPatch
+        The pytest monkeypatch fixture for mocking.
+    generic_motor : rocketpy.GenericMotor
+        The GenericMotor object to be used in the tests.
+
+    """
+
+    class MockResponse:
+        def __init__(self, json_data):
+            self._json_data = json_data
+
+        def json(self):
+            return self._json_data
+
+        def raise_for_status(self):
+            # Simulate a successful HTTP response (200)
+            return None
+
+    # Provide mocked responses for the two endpoints: search.json and download.json
+    def mock_get(url, params=None):
+        if "search.json" in url:
+            # Return a mock search result with a motorId and designation
+            return MockResponse(
+                {
+                    "results": [
+                        {
+                            "motorId": "12345",
+                            "designation": "Cesaroni_M1670",
+                            "manufacturer": "Cesaroni",
+                        }
+                    ]
+                }
+            )
+        elif "download.json" in url:
+            # Read the local .eng file and return its base64-encoded content as the API would
+            eng_path = "data/motors/cesaroni/Cesaroni_M1670.eng"
+            with open(eng_path, "rb") as f:
+                encoded = base64.b64encode(f.read()).decode("utf-8")
+            return MockResponse({"results": [{"data": encoded}]})
+        else:
+            raise RuntimeError(f"Unexpected URL called in test mock: {url}")
+
+    monkeypatch.setattr(requests, "get", mock_get)
+
+    # Expected parameters from the original test
+    burn_time = (0, 3.9)
+    dry_mass = 5.231 - 3.101  # 2.130 kg
+    propellant_initial_mass = 3.101
+    chamber_radius = 75 / 1000
+    chamber_height = 757 / 1000
+    nozzle_radius = chamber_radius * 0.85  # 85% of chamber radius
+
+    average_thrust = 1545.218
+    total_impulse = 6026.350
+    max_thrust = 2200.0
+    exhaust_velocity = 1943.357
+
+    # Call the method using the class (works if it's a staticmethod); using type(generic_motor)
+    # ensures test works if the method is invoked on a GenericMotor instance in the project
+    motor = type(generic_motor).load_from_thrustcurve_api("M1670")
+
+    # Assertions (same as original)
+    assert motor.burn_time == burn_time
+    assert motor.dry_mass == dry_mass
+    assert motor.propellant_initial_mass == propellant_initial_mass
+    assert motor.chamber_radius == chamber_radius
+    assert motor.chamber_height == chamber_height
+    assert motor.chamber_position == 0
+    assert motor.average_thrust == pytest.approx(average_thrust)
+    assert motor.total_impulse == pytest.approx(total_impulse)
+    assert motor.exhaust_velocity.average(*burn_time) == pytest.approx(exhaust_velocity)
+    assert motor.max_thrust == pytest.approx(max_thrust)
+    assert motor.nozzle_radius == pytest.approx(nozzle_radius)
+
+    # testing thrust curve equality against the local .eng import (as in original test)
+    _, _, points = Motor.import_eng("data/motors/cesaroni/Cesaroni_M1670.eng")
+    assert motor.thrust.y_array == pytest.approx(
+        Function(points, "Time (s)", "Thrust (N)", "linear", "zero").y_array
+    )
+
+    # 1. No motor found
+    def mock_get_no_motor(url, params=None):
+        if "search.json" in url:
+            return MockResponse({"results": []})
+        return MockResponse({"results": []})
+
+    monkeypatch.setattr(requests, "get", mock_get_no_motor)
+    with pytest.raises(ValueError, match="No motor found"):
+        type(generic_motor).load_from_thrustcurve_api("NonexistentMotor")
+
+    # 2. No .eng file found
+    def mock_get_no_eng(url, params=None):
+        if "search.json" in url:
+            return MockResponse(
+                {
+                    "results": [
+                        {
+                            "motorId": "123",
+                            "designation": "Fake",
+                            "manufacturer": "Test",
+                        }
+                    ]
+                }
+            )
+        elif "download.json" in url:
+            return MockResponse({"results": []})
+        return MockResponse({})
+
+    monkeypatch.setattr(requests, "get", mock_get_no_eng)
+    with pytest.raises(ValueError, match="No .eng file found"):
+        type(generic_motor).load_from_thrustcurve_api("FakeMotor")
+
+    # 3. Empty .eng data
+    def mock_get_empty_data(url, params=None):
+        if "search.json" in url:
+            return MockResponse(
+                {
+                    "results": [
+                        {
+                            "motorId": "123",
+                            "designation": "Fake",
+                            "manufacturer": "Test",
+                        }
+                    ]
+                }
+            )
+        elif "download.json" in url:
+            return MockResponse({"results": [{"data": ""}]})
+        return MockResponse({})
+
+    monkeypatch.setattr(requests, "get", mock_get_empty_data)
+    with pytest.raises(ValueError, match="Downloaded .eng data"):
+        type(generic_motor).load_from_thrustcurve_api("FakeMotor")