FIX: `to_table` failed on lists

Summary

Fix for #117 (closed)

Focus

• Performance
• Sufficient test

Test Environment

Run the unit test:

pytest --pdb --pdbcls=IPython.terminal.debugger:TerminalPdb unittests/test_table_converter.py::TableTest::test_list

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src/caosadvancedtools/table_converter.py

@@ -25,6 +25,7 @@ import re
 import sys
 
 import caosdb as db
+import numpy as np
 import pandas as pd
 
 
@@ -58,15 +59,20 @@ def to_table(container):
         properties.update([generate_property_name(p)
                            for p in container[0].get_properties()])
     df = pd.DataFrame(columns=list(properties))
-    rts = set([p.name for p in container[0].parents])
+    rts = {p.name for p in container[0].parents}
 
     for ii, rec in enumerate(container):
-        if set([p.name for p in rec.parents]) != rts:
+        if {p.name for p in rec.parents} != rts:
             raise ValueError("Parents differ")
 
-        for p in rec.get_properties():
-
-            df.loc[ii, generate_property_name(p)] = p.value
+        for prop in rec.get_properties():
+            propname = generate_property_name(prop)
+            if isinstance(prop.value, list):
+                if propname not in df:
+                    df[propname] = pd.Series(dtype=object)
+                elif df[propname].dtype != object:
+                    df[propname] = df[propname].astype(object)
+            df.at[ii, propname] = prop.value
 
     return df