Move optimade dependency as extra dependency

aiidalab_widgets_base/databases.py

@@ -156,7 +156,17 @@ def __init__(
         title: str = None,
         **kwargs,
     ) -> None:
-        from optimade_client import default_parameters, query_filter, query_provider
+        try:
+            from optimade_client import default_parameters, query_filter, query_provider
+        except ImportError:
+            super().__init__(
+                [
+                    ipw.HTML(
+                        "This widget requires the `optimade-client` package to be installed."
+                    )
+                ]
+            )
+            return
 
         providers_header = ipw.HTML("<h4>Select a provider</h4>")
         providers = query_provider.OptimadeQueryProviderWidget(

setup.cfg

@@ -34,7 +34,6 @@ install_requires =
     more-itertools~=8.0
     pymysql~=0.9
     nglview~=3.0
-    optimade-client==2022.9.19
     spglib>=1.14,<3
     vapory~=0.1.2
 python_requires = >=3.8
@@ -56,6 +55,8 @@ dev =
     pytest-timeout~=2.2
     selenium~=4.7.0
     webdriver-manager~=3.8
+optimade =
+    optimade-client==2022.9.19
 smiles =
     rdkit>=2021.09.2
     scikit-learn~=1.0.0