Make cell (default) color configurable

This only applies to columns with a fixed color, i.e. that does not
depend on the value (like do the 'time' or 'state' columns).

Although this limitation is not handled in the Configuration class, we
intercept invalid 'color' option in column configuration while loading
the types.UI object and still return a ConfigurationError so that the
user experience is quite similar.

Author: dlax

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## pg\_activity 3.6.0 - UNRELEASED
 
+### Added
+
+* The color of cells in the process table can now be customized through the
+  configuration file.
+
 ### Changed
 
 * Exit with status 0 upon keyboard interrupt.

README.md

@@ -180,6 +180,24 @@ same as the main configuration file.
 - `minimal`, providing an even more minimal user interface with header
   information hidden
 
+Columns of the process table in pg\_activity user interface can be assigned a
+custom color in the configuration file, e.g.:
+```ini
+[client]
+color = magenta
+
+[relation]
+color = red
+```
+
+The `color` option illustrated above defines the color used to render the cell
+independently of its value, i.e. the "normal" color. Some columns may be
+colorized differently depending on the value of their cells; for example, the
+`time` column can handle tree colors depending on whether the time value is
+*high*, *medium* or *low*. The color of such columns cannot be currently
+customized and attempting to do so will result in pg\_activity to exit early
+with an error message.
+
 [INI format]: https://docs.python.org/3/library/configparser.html#supported-ini-file-structure
 
 ## Notes

pgactivity/cli.py

@@ -425,6 +425,8 @@ def main() -> None:
     while True:
         try:
             ui.main(term, cfg, dataobj, host, args)
+        except ConfigurationError as e:
+            parser.exit(1, f"error: {e}")
         except OperationalError:
             while True:
                 print(term.clear + term.home, end="")

pgactivity/config.py

@@ -202,6 +202,7 @@ def from_config_section(cls: type[_T], section: configparser.SectionProxy) -> _T
 class UISection(BaseSectionMixin):
     hidden: bool = False
     width: int | None = attr.ib(default=None, validator=validators.optional(gt(0)))
+    color: str | None = attr.ib(default=None)
 
     _T = TypeVar("_T", bound="UISection")
 
@@ -213,6 +214,7 @@ def from_config_section(cls: type[_T], section: configparser.SectionProxy) -> _T
         if hidden is not None:
             values["hidden"] = hidden
         values["width"] = section.getint("width")
+        values["color"] = section.get("color")
         return cls(**values)
 
 
@@ -262,12 +264,12 @@ def parse(cls: type[_T], f: IO[str], name: str) -> _T:
         >>> from io import StringIO
         >>> from pprint import pprint
 
-        >>> f = StringIO('[header]\nshow_workers=false\n[client]\nhidden=true\n')
+        >>> f = StringIO('[header]\nshow_workers=false\n[client]\nhidden=true\ncolor=green\n')
         >>> cfg = Configuration.parse(f, "f.ini")
         >>> cfg.name
         'f.ini'
         >>> pprint(cfg.values)
-        {'client': UISection(hidden=True, width=None),
+        {'client': UISection(hidden=True, width=None, color='green'),
          'header': HeaderSection(show_instance=True, show_system=True, show_workers=False)}
 
         >>> bad = StringIO("[global]\nx=1")

pgactivity/types.py

@@ -301,6 +301,12 @@ def add_column(key: str, name: str, **kwargs: Any) -> None:
                     assert isinstance(cfg, UISection), cfg
                     if cfg.width is not None:
                         kwargs["min_width"] = kwargs["max_width"] = cfg.width
+                    if cfg.color is not None:
+                        if kwargs.get("value_color"):
+                            raise config.error(
+                                f"the color for '{name}' column (option '{key}') cannot be configured"
+                            )
+                        kwargs["default_color"] = cfg.color
             assert key not in possible_columns, f"duplicated key {key}"
             possible_columns[key] = Column(key=key, name=name, **kwargs)
 

tests/test_config.py

@@ -101,14 +101,15 @@ def test_lookup(tmp_path: Path) -> None:
             [
                 "[client]",
                 "width=5",
+                "color=cyan",
                 "[header]",
                 "show_instance=no",
             ]
         )
     )
     cfg = Configuration.lookup(None, user_config_home=tmp_path)
     assert cfg is not None and asdict(cfg) == {
-        "client": {"hidden": False, "width": 5},
+        "client": {"hidden": False, "width": 5, "color": "cyan"},
         "header": {"show_instance": False, "show_system": True, "show_workers": True},
     }
 
@@ -120,7 +121,7 @@ def test_lookup(tmp_path: Path) -> None:
     )
     cfg = Configuration.lookup("x", user_config_home=tmp_path)
     assert cfg is not None and asdict(cfg) == {
-        "database": {"hidden": True, "width": 3},
+        "database": {"hidden": True, "width": 3, "color": None},
         "header": {"show_instance": True, "show_system": True, "show_workers": False},
     }
 
@@ -132,8 +133,8 @@ def test_lookup(tmp_path: Path) -> None:
     "header": {k: False for k in ("show_instance", "show_system", "show_workers")}
 }
 columns = ("database", "user", "client", "cpu", "mem", "read", "write", "appname")
-narrow = {k: {"hidden": True, "width": None} for k in columns}
-wide = {k: {"hidden": False, "width": None} for k in columns}
+narrow = {k: {"hidden": True, "width": None, "color": None} for k in columns}
+wide = {k: {"hidden": False, "width": None, "color": None} for k in columns}
 minimal = {**no_header, **narrow}