diff --git a/api/schemas.py b/api/schemas.py
index 6e59bdafd..c5d6945db 100644
--- a/api/schemas.py
+++ b/api/schemas.py
@@ -742,12 +742,6 @@ class MetricType(str, Enum):
     table = "table"
 
 
-# class MetricTypeTableGroupField(str, Enum):
-#     users = "USERS"
-#     click_rage = IssueType.click_rage
-#     dead_click = IssueType.dead_click
-
-
 class CustomMetricRawPayloadSchema(BaseModel):
     startDate: int = Field(TimeUTC.now(-7))
     endDate: int = Field(TimeUTC.now())
@@ -760,7 +754,7 @@ class CustomMetricRawPayloadSchema2(CustomMetricRawPayloadSchema):
     metric_id: int = Field(...)
 
 
-class MetricOfType(str, Enum):
+class TableMetricOfType(str, Enum):
     user_os = FilterType.user_os.value
     user_browser = FilterType.user_browser.value
     user_device = FilterType.user_device.value
@@ -770,14 +764,25 @@ class MetricOfType(str, Enum):
     visited_url = "VISITED_URL"
 
 
+class TimeseriesMetricOfType(str, Enum):
+    session_count = "sessionCount"
+
+
 class CustomMetricChartPayloadSchema(CustomMetricRawPayloadSchema):
     startDate: int = Field(TimeUTC.now(-7))
     endDate: int = Field(TimeUTC.now())
     density: int = Field(7)
     viewType: MetricViewType = Field(MetricViewType.line_chart)
     metricType: MetricType = Field(MetricType.timeseries)
-    metricOf: MetricOfType = Field(MetricOfType.user_id)
-    metricFraction: float = Field(None, gt=0, lt=1)
+    metricOf: Union[TableMetricOfType, TimeseriesMetricOfType] = Field(TableMetricOfType.user_id)
+
+    # metricFraction: float = Field(None, gt=0, lt=1)
+    @root_validator
+    def validator(cls, values):
+        if isinstance(values.get("metricOf"), TimeseriesMetricOfType):
+            assert values.get("metricType") == MetricType.timeseries, \
+                f"Only metricType:{MetricType.timeseries.value} is allowed for metricOf: {values.get('metricOf')}"
+        return values
 
 
 class CustomMetricChartPayloadSchema2(CustomMetricChartPayloadSchema):