Expose some timeseries from TimescaleDB over Django

ram/ram/db_router.py

@@ -0,0 +1,32 @@
+class TelemetryRouter:
+    db_table = "telemetry_10secs"
+
+    def db_for_read(self, model, **hints):
+        """Send read operations to the correct database."""
+        if model._meta.db_table == self.db_table:
+            return "telemetry"  # Replace with your database name
+        return None  # Default database
+
+    def db_for_write(self, model, **hints):
+        """Send write operations to the correct database."""
+        if model._meta.db_table == self.db_table:
+            return False  # Prevent Django from writing RO tables
+        return None
+
+    def allow_relation(self, obj1, obj2, **hints):
+        """
+        Allow relations if a model in the auth or contenttypes apps is
+        involved.
+        """
+        if (
+            obj1._meta.db_table == self.db_table
+            or obj2._meta.db_table == self.db_table
+        ):
+            return True
+        return None
+
+    def allow_migrate(self, db, app_label, model_name=None, **hints):
+        """Prevent Django from migrating this model if it's using a specific database."""
+        if db == "telemetry":
+            return False  # Prevent Django from creating/modifying tables
+        return None

ram/ram/settings.py

@@ -95,8 +95,16 @@ DATABASES = {
     "default": {
         "ENGINE": "django.db.backends.sqlite3",
         "NAME": STORAGE_DIR / "db.sqlite3",
+    },
+    "telemetry": {
+        "ENGINE": "django.db.backends.postgresql",
+        "HOST": "127.0.0.1",
+        "NAME": "dccmonitor",
+        "USER": "dccmonitor",
+        "PASSWORD": "dccmonitor",
+    },
 }
-}
+DATABASE_ROUTERS = ["ram.db_router.TelemetryRouter"]
 
 
 # Password validation

ram/roster/admin.py

@@ -17,6 +17,7 @@ from roster.models import (
     RollingStockImage,
     RollingStockProperty,
     RollingStockJournal,
+    RollingStockTelemetry,
 )
 
 
@@ -287,3 +288,29 @@ class RollingStockAdmin(SortableAdminBase, admin.ModelAdmin):
 
     download_csv.short_description = "Download selected items as CSV"
     actions = [publish, unpublish, download_csv]
+
+
+@admin.register(RollingStockTelemetry)
+class RollingTelemtryAdmin(admin.ModelAdmin):
+    list_filter = ("bucket", "cab")
+    list_display = ("bucket_highres", "cab", "max_speed", "avg_speed")
+
+    def bucket_highres(self, obj):
+        return obj.bucket.strftime("%Y-%m-%d %H:%M:%S")
+
+    bucket_highres.admin_order_field = "bucket"  # Enable sorting
+    bucket_highres.short_description = "Bucket"  # Column name in admin
+
+    def get_changelist_instance(self, request):
+        changelist = super().get_changelist_instance(request)
+        changelist.list_display_links = None  # Disable links
+        return changelist
+
+    def has_add_permission(self, request):
+        return False  # Disable adding new objects
+
+    def has_change_permission(self, request, obj=None):
+        return False  # Disable editing objects
+
+    def has_delete_permission(self, request, obj=None):
+        return False  # Disable deleting objects

ram/roster/models.py

@@ -224,6 +224,20 @@ class RollingStockJournal(models.Model):
     objects = PublicManager()
 
 
+# trick: this is technically an abstract class
+# it is made readonly via db_router and admin to avoid any unwanted change
+class RollingStockTelemetry(models.Model):
+    bucket = models.DateTimeField(primary_key=True, editable=False)
+    cab = models.PositiveIntegerField(editable=False)
+    avg_speed = models.FloatField(editable=False)
+    max_speed = models.PositiveIntegerField(editable=False)
+
+    class Meta:
+        db_table = "telemetry_10secs"
+        ordering = ["cab", "bucket"]
+        verbose_name_plural = "Telemetries"
+
+
 # @receiver(models.signals.post_delete, sender=Cab)
 # def post_save_image(sender, instance, *args, **kwargs):
 #     try:

requirements.txt

@@ -8,7 +8,7 @@ django-countries
 django-health-check
 django-admin-sortable2
 django-tinymce
-# Optional: # psycopg2-binary
+psycopg2-binary
 # Required by django-countries and not always installed
 # by default on modern venvs (like Python 3.12 on Fedora 39)
 setuptools