stream output to command stdout/stderr

Author: bckohan

django_routines/__init__.py

@@ -74,6 +74,19 @@ class _RoutineCommand(ABC):
     or for all invocations of the routine if no switches are configured.
     """
 
+    # pre_hook: t.Optional[t.Callable[[Command], t.Optional[bool]]] = None
+    """
+    A function to run before the command is run. The function should take the command instance and
+    may return True to skip the command.
+    """
+
+    # post_hook: t.Optional[t.Callable[[Command, t.Any], t.Any]] = None
+    """
+    A function to run after the command has been run. The function should take the command instance
+    and the result of the function which will be whatever call_command returns if run in the same
+    process, or the result object returned by subprocess.run() if run in a subprocess.
+    """
+
     @property
     @abstractmethod
     def kind(self) -> str:

django_routines/management/commands/routine.py

@@ -217,10 +217,38 @@ def _subprocess(self, command: RCommand):
         if self.verbosity > 0:
             self.secho(" ".join(args), fg="cyan")
 
-        result = subprocess.run(args, env=os.environ.copy(), capture_output=True)
-        self.stdout.write(result.stdout.decode())
-        self.stderr.write(result.stderr.decode())
-        return result.returncode
+        # result = subprocess.run(args, env=os.environ.copy(), capture_output=True)
+        # self.stdout.write(result.stdout.decode())
+        # self.stderr.write(result.stderr.decode())
+
+        with subprocess.Popen(
+            args,
+            env=os.environ.copy(),
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True,
+        ) as proc:
+            assert proc.stdout
+            assert proc.stderr
+            while True:
+                output = proc.stdout.readline()
+                if output:
+                    self.stdout.write(output)
+                    self.stdout.flush()
+                error = proc.stderr.readline()
+                if error:
+                    self.stderr.write(error)
+                    self.stderr.flush()
+
+                if output == "" and error == "" and proc.poll() is not None:
+                    break
+
+            if proc.returncode != 0:
+                for line in proc.stderr:
+                    self.stderr.write(line)
+                    self.stderr.flush()
+
+            return proc.returncode
 
     def _list(self) -> None:
         """

doc/source/changelog.rst

@@ -5,6 +5,7 @@ Change Log
 v1.1.0
 ======
 
+* `Support function pre and post hooks to be run prior to and after given commands. <https://github.com/bckohan/django-routines/issues/9>`_
 * `Command type for system commands (i.e. non-management commands) to be run as subprocesses <https://github.com/bckohan/django-routines/issues/7>`_
 * `Option to run management commands as subprocesses instead of in the same process space. <https://github.com/bckohan/django-routines/issues/6>`_
 

tests/pytest_routine.py

@@ -0,0 +1,6 @@
+from .settings import *
+from django_routines import system
+
+DJANGO_ROUTINES = {}
+
+system('test', 'pytest')