feat(duckdb): allow casting to geometry from text (ibis-project#10221)

Playing around the [MTA bus time
dataset](https://data.ny.gov/Transportation/MTA-Bus-Route-Segment-Speeds-Beginning-2023/58t6-89vi/about_data),
I wanted this to work and found a bug, where casting to geospatial from
a non binary type failed because of an implicit assumption that that non
binary type was geospatial, as well as a missing feature which was to
handle to cast from string -> geo*

ibis/backends/duckdb/tests/test_geospatial.py

@@ -385,3 +385,12 @@ def test_load_spatial_casting(ext_dir):
 
     assert geo_expr.type().is_geospatial()
     assert isinstance(con.execute(geo_expr), gpd.GeoSeries)
+
+
+def test_geom_from_string(con):
+    value = ibis.literal("POINT (1 2)")
+    assert value.type().is_string()
+
+    expr = value.cast("geometry")
+    result = con.execute(expr)
+    assert result == shapely.from_wkt("POINT (1 2)")

ibis/backends/sql/compilers/duckdb.py

@@ -410,13 +410,17 @@ def visit_TimestampFromYMDHMS(
         return self.f[func](*args)
 
     def visit_Cast(self, op, *, arg, to):
+        dtype = op.arg.dtype
         if to.is_interval():
             func = self.f[f"to_{_INTERVAL_SUFFIXES[to.unit.short]}"]
             return func(sg.cast(arg, to=self.type_mapper.from_ibis(dt.int32)))
-        elif to.is_timestamp() and op.arg.dtype.is_integer():
+        elif to.is_timestamp() and dtype.is_integer():
             return self.f.to_timestamp(arg)
-        elif to.is_geospatial() and op.arg.dtype.is_binary():
-            return self.f.st_geomfromwkb(arg)
+        elif to.is_geospatial():
+            if dtype.is_binary():
+                return self.f.st_geomfromwkb(arg)
+            elif dtype.is_string():
+                return self.f.st_geomfromtext(arg)
 
         return self.cast(arg, to)
 

ibis/expr/types/generic.py

@@ -203,16 +203,17 @@ def cast(self, target_type: Any) -> Value:
         """
         op = ops.Cast(self, to=target_type)
 
-        if op.to == self.type():
-            # noop case if passed type is the same
+        to = op.to
+        dtype = self.type()
+
+        if to == dtype or (
+            to.is_geospatial()
+            and dtype.is_geospatial()
+            and (dtype.geotype or "geometry") == to.geotype
+        ):
+            # no-op case if passed type is the same
             return self
 
-        if op.to.is_geospatial() and not self.type().is_binary():
-            from_geotype = self.type().geotype or "geometry"
-            to_geotype = op.to.geotype
-            if from_geotype == to_geotype:
-                return self
-
         return op.to_expr()
 
     def try_cast(self, target_type: Any) -> Value: