Fix: Use correct OpenMetadata API field names for metrics

OpenMetadata uses different field names than expected:
- metricExpression instead of expression
- metricType instead of type
- unitOfMeasurement instead of unit
- granularity instead of grain

Remove 'fields' query parameter from /api/v1/metrics - returns 400 Bad Request
when invalid field names are specified. Let API return full metric objects.

Update parsing to extract metadata from proper OpenMetadata fields instead
of relying on tags (tags are optional, fields are always present).

connectors/openmetadata/client.py

@@ -98,12 +98,11 @@ class OpenMetadataClient:
             List of metric dictionaries with:
             - id, name, fullyQualifiedName
             - description
-            - expression: metric calculation SQL/formula
+            - metricExpression: metric calculation SQL/formula
             - owners, tags
         """
         params = {
             "limit": limit,
-            "fields": "description,expression,owners,tags",
         }
 
         response = self._client.get("/api/v1/metrics", params=params)
@@ -117,23 +116,20 @@ class OpenMetadataClient:
         Fetch a specific metric by FQN from OpenMetadata.
 
         Args:
-            fqn: Fully qualified name (e.g., "catalog.metrics.total_revenue")
+            fqn: Fully qualified name (e.g., "Active2 Customers")
 
         Returns:
             Dictionary with metric metadata:
             - id, name, fullyQualifiedName
-            - description, expression
+            - description, metricExpression
             - owners, tags
 
         Raises:
             httpx.HTTPStatusError: If request fails (non-2xx status)
         """
         url = f"/api/v1/metrics/name/{fqn}"
-        params = {
-            "fields": "description,expression,owners,tags,displayName",
-        }
 
-        response = self._client.get(url, params=params)
+        response = self._client.get(url)
         response.raise_for_status()
 
         return response.json()

webapp/app.py

@@ -554,10 +554,10 @@ def _parse_om_metric(raw_metric: dict) -> dict:
     display_name = raw_metric.get("displayName", name)
     description = raw_metric.get("description", "") or ""
 
-    # Extract category and grain from tags
+    # Extract category from tags, grain from granularity field
     tags = raw_metric.get("tags", [])
     category = "general"
-    grain = ""
+    grain = raw_metric.get("granularity", "") or ""
 
     for tag in tags:
         tag_fqn = tag.get("tagFQN", "")
@@ -568,15 +568,11 @@ def _parse_om_metric(raw_metric: dict) -> dict:
         elif tag_fqn.startswith("Category."):
             category = tag_fqn.split(".", 1)[1]
 
-        # Extract grain from Grain.* tags
-        if tag_fqn.startswith("Grain."):
-            grain = tag_fqn.split(".", 1)[1]
-
     return {
         "name": name,
         "display_name": display_name,
         "description": description,
-        "grain": grain,
+        "grain": grain.lower() if grain else "",  # Normalize to lowercase
         "category": category,
         "path": f"catalog:{fqn}",  # Special prefix for JS routing
     }
@@ -659,7 +655,7 @@ def _build_om_metric_detail(raw_metric: dict) -> dict:
     Convert raw OpenMetadata metric into MetricParser-compatible JSON for modal.
 
     Maps OpenMetadata fields to MetricParser structure (name, display_name, category, metadata, etc.).
-    Extracts type, unit, grain from tags with standard prefixes.
+    Extracts type, unit, grain from OpenMetadata fields (metricType, unitOfMeasurement, granularity).
 
     Args:
         raw_metric: Raw metric dict from OpenMetadata
@@ -671,27 +667,30 @@ def _build_om_metric_detail(raw_metric: dict) -> dict:
     name = raw_metric.get("name", "")
     display_name = raw_metric.get("displayName", name)
     description = raw_metric.get("description", "") or ""
-    expression = raw_metric.get("expression", "") or ""
+
+    # OpenMetadata uses metricExpression instead of expression
+    expression = ""
+    metric_expr = raw_metric.get("metricExpression", {})
+    if isinstance(metric_expr, dict):
+        expression = metric_expr.get("expression", "") or ""
+    elif isinstance(metric_expr, str):
+        expression = metric_expr
+
     owners = raw_metric.get("owners", [])
 
-    # Extract metadata from tags
-    tags = raw_metric.get("tags", [])
-    metric_type = ""
-    unit = ""
-    grain = ""
+    # Extract metadata from OpenMetadata fields and tags
+    metric_type = raw_metric.get("metricType", "") or ""
+    unit = raw_metric.get("unitOfMeasurement", "") or ""
+    grain = raw_metric.get("granularity", "") or ""
     category = "general"
     dimensions = []
 
+    # Also check tags for category and dimensions
+    tags = raw_metric.get("tags", [])
     for tag in tags:
         tag_fqn = tag.get("tagFQN", "")
 
-        if tag_fqn.startswith("MetricType."):
-            metric_type = tag_fqn.split(".", 1)[1]
-        elif tag_fqn.startswith("Unit."):
-            unit = tag_fqn.split(".", 1)[1]
-        elif tag_fqn.startswith("Grain."):
-            grain = tag_fqn.split(".", 1)[1]
-        elif tag_fqn.startswith("MetricCategory."):
+        if tag_fqn.startswith("MetricCategory."):
             category = tag_fqn.split(".", 1)[1]
         elif tag_fqn.startswith("Dimension."):
             dimensions.append(tag_fqn.split(".", 1)[1])