Adding LocationEncoder to store Locations as JSON

docs/direct_api_reference.rst

@@ -30,6 +30,7 @@ CAD objects described in the following section are frequently of these types.
    :special-members: __copy__,__deepcopy__
 .. autoclass:: Location
    :special-members: __copy__,__deepcopy__, __mul__, __pow__, __eq__, __neg__
+.. autoclass:: LocationEncoder
 .. autoclass:: Pos
 .. autoclass:: Rot
 .. autoclass:: Matrix

src/build123d/__init__.py

@@ -138,6 +138,7 @@
     "Plane",
     "Compound",
     "Location",
+    "LocationEncoder",
     "Joint",
     "RigidJoint",
     "RevoluteJoint",

src/build123d/geometry.py

@@ -34,6 +34,7 @@
 #   too-many-arguments, too-many-locals, too-many-public-methods,
 #   too-many-statements, too-many-instance-attributes, too-many-branches
 import copy
+import json
 import logging
 from math import degrees, pi, radians
 from typing import Any, Iterable, List, Optional, Sequence, Tuple, Union, overload
@@ -1092,7 +1093,7 @@ def __init__(self, *args):
         elif len(args) == 1:
             translation = args[0]
 
-            if isinstance(translation, (Vector, tuple)):
+            if isinstance(translation, (Vector, Iterable)):
                 transform.SetTranslationPart(Vector(translation).wrapped)
             elif isinstance(translation, Plane):
                 coordinate_system = gp_Ax3(
@@ -1114,8 +1115,8 @@ def __init__(self, *args):
                 raise TypeError("Unexpected parameters")
 
         elif len(args) == 2:
-            if isinstance(args[0], (Vector, tuple)):
-                if isinstance(args[1], (Vector, tuple)):
+            if isinstance(args[0], (Vector, Iterable)):
+                if isinstance(args[1], (Vector, Iterable)):
                     rotation = [radians(a) for a in args[1]]
                     quaternion = gp_Quaternion()
                     quaternion.SetEulerAngles(
@@ -1248,6 +1249,48 @@ def __str__(self):
         return f"Location: (position=({position_str}), orientation=({orientation_str}))"
 
 
+class LocationEncoder(json.JSONEncoder):
+    """Custom JSON Encoder for Location values
+
+    Example:
+
+    .. code::
+
+        data_dict = {
+            "part1": {
+                "joint_one": Location((1, 2, 3), (4, 5, 6)),
+                "joint_two": Location((7, 8, 9), (10, 11, 12)),
+            },
+            "part2": {
+                "joint_one": Location((13, 14, 15), (16, 17, 18)),
+                "joint_two": Location((19, 20, 21), (22, 23, 24)),
+            },
+        }
+        json_object = json.dumps(data_dict, indent=4, cls=LocationEncoder)
+        with open("sample.json", "w") as outfile:
+            outfile.write(json_object)
+        with open("sample.json", "r") as infile:
+            copy_data_dict = json.load(infile, object_hook=LocationEncoder.location_hook)
+
+    """
+
+    def default(self, loc: Location) -> dict:
+        """Return a serializable object"""
+        if not isinstance(loc, Location):
+            raise TypeError("Only applies to Location objects")
+        return {"Location": loc.to_tuple()}
+
+    def location_hook(obj) -> dict:
+        """Convert Locations loaded from json to Location objects
+
+        Example:
+            read_json = json.load(infile, object_hook=LocationEncoder.location_hook)
+        """
+        if "Location" in obj:
+            obj = Location(*[[float(f) for f in v] for v in obj["Location"]])
+        return obj
+
+
 class Rotation(Location):
     """Subclass of Location used only for object rotation
 

tests/test_direct_api.py

@@ -1,5 +1,6 @@
 # system modules
 import copy
+import json
 import math
 import os
 import platform
@@ -53,6 +54,7 @@
     BoundBox,
     Color,
     Location,
+    LocationEncoder,
     Matrix,
     Pos,
     Rot,
@@ -1393,6 +1395,12 @@ def test_location(self):
         T = loc0.wrapped.Transformation().TranslationPart()
         self.assertTupleAlmostEquals((T.X(), T.Y(), T.Z()), (0, 0, 1), 6)
 
+        # List
+        loc0 = Location([0, 0, 1])
+
+        T = loc0.wrapped.Transformation().TranslationPart()
+        self.assertTupleAlmostEquals((T.X(), T.Y(), T.Z()), (0, 0, 1), 6)
+
         # Vector
         loc1 = Location(Vector(0, 0, 1))
 
@@ -1451,8 +1459,6 @@ def test_location(self):
         self.assertAlmostEqual(30, angle7)
 
         # Test error handling on creation
-        with self.assertRaises(TypeError):
-            Location([0, 0, 1])
         with self.assertRaises(TypeError):
             Location("xy_plane")
 
@@ -1557,6 +1563,44 @@ def test_neg(self):
         self.assertVectorAlmostEquals(n_loc.position, (1, 2, 3), 5)
         self.assertVectorAlmostEquals(n_loc.orientation, (180, -35, -127), 5)
 
+    def test_as_json(self):
+        data_dict = {
+            "part1": {
+                "joint_one": Location((1, 2, 3), (4, 5, 6)),
+                "joint_two": Location((7, 8, 9), (10, 11, 12)),
+            },
+            "part2": {
+                "joint_one": Location((13, 14, 15), (16, 17, 18)),
+                "joint_two": Location((19, 20, 21), (22, 23, 24)),
+            },
+        }
+
+        # Serializing json with custom Location encoder
+        json_object = json.dumps(data_dict, indent=4, cls=LocationEncoder)
+
+        # Writing to sample.json
+        with open("sample.json", "w") as outfile:
+            outfile.write(json_object)
+
+        # Reading from sample.json
+        with open("sample.json", "r") as infile:
+            read_json = json.load(infile, object_hook=LocationEncoder.location_hook)
+
+        # Validate locations
+        for key, value in read_json.items():
+            for k, v in value.items():
+                if key == "part1" and k == "joint_one":
+                    self.assertVectorAlmostEquals(v.position, (1, 2, 3), 5)
+                elif key == "part1" and k == "joint_two":
+                    self.assertVectorAlmostEquals(v.position, (7, 8, 9), 5)
+                elif key == "part2" and k == "joint_one":
+                    self.assertVectorAlmostEquals(v.position, (13, 14, 15), 5)
+                elif key == "part2" and k == "joint_two":
+                    self.assertVectorAlmostEquals(v.position, (19, 20, 21), 5)
+                else:
+                    self.assertTrue(False)
+        os.remove("sample.json")
+
 
 class TestMatrix(DirectApiTestCase):
     def test_matrix_creation_and_access(self):