Chart Parameters

Chart parameters are stored as a JSON encoded string in the slices.params column and are often referenced throughout the code as form-data. Currently the form-data is neither versioned nor typed as thus is somewhat free-formed. Note in the future there may be merit in using something like JSON Schema to both annotate and validate the JSON object in addition to using a Mypy TypedDict (introduced in Python 3.8) for typing the form-data in the backend. This section serves as a potential primer for that work.

The following tables provide a non-exhaustive list of the various fields which can be present in the JSON object grouped by the Explorer pane sections. These values were obtained by extracting the distinct fields from a legacy deployment consisting of tens of thousands of charts and thus some fields may be missing whilst others may be deprecated.

Note not all fields are correctly categorized. The fields vary based on visualization type and may appear in different sections depending on the type. Verified deprecated columns may indicate a missing migration and/or prior migrations which were unsuccessful and thus future work may be required to clean up the form-data.

Datasource & Chart Type

Field	Type	Notes
database_name	string	Deprecated?
datasource	string	<datasource_id>__<datasource_type>
datasource_id	string	Deprecated? See datasource
datasource_name	string	Deprecated?
datasource_type	string	Deprecated? See datasource
viz_type	string	The Visualization Type widget

Time

Field	Type	Notes
granularity_sqla	string	The SQLA Time Column widget
time_grain_sqla	string	The SQLA Time Grain widget
time_range	string	The Time range widget

GROUP BY

Field	Type	Notes
metrics	array(string)	See Query section
order_asc	-	See Query section
row_limit	-	See Query section
timeseries_limit_metric	-	See Query section

NOT GROUPED BY

Field	Type	Notes
order_by_cols	array(string)	The Ordering widget
row_limit	-	See Query section

Y Axis 1

Field	Type	Notes
metric	-	The Left Axis Metric widget. See Query section
y_axis_format	-	See Y Axis section

Y Axis 2

Field	Type	Notes
metric_2	-	The Right Axis Metric widget. See Query section

Query

Field	Type	Notes
adhoc_filters	array(object)	The Filters widget
extra_filters	array(object)	Another pathway to the Filters widget. It is generally used to pass dashboard filter parameters to a chart. It can be used for appending additional filters to a chart that has been saved with its own filters on an ad-hoc basis if the chart is being used as a standalone widget. For implementation examples see : utils test.py For insight into how superset processes the contents of this parameter see: exploreUtils/index.js
columns	array(string)	The Breakdowns widget
groupby	array(string)	The Group by or Series widget
limit	number	The Series Limit widget
metric metric_2 metrics percent_metrics secondary_metric size x y	string,object,array(string),array(object)	The metric(s) depending on the visualization type
order_asc	boolean	The Sort Descending widget
row_limit	number	The Row limit widget
timeseries_limit_metric	object	The Sort By widget

The metric (or equivalent) and timeseries_limit_metric fields are all composed of either metric names or the JSON representation of the AdhocMetric TypeScript type. The adhoc_filters is composed of the JSON represent of the AdhocFilter TypeScript type (which can comprise of columns or metrics depending on whether it is a WHERE or HAVING clause). The all_columns, all_columns_x, columns, groupby, and order_by_cols fields all represent column names.

Chart Options

Field	Type	Notes
color_picker	object	The Fixed Color widget
label_colors	object	The Color Scheme widget
normalized	boolean	The Normalized widget

Y Axis

Field	Type	Notes
y_axis_2_label	N/A	Deprecated?
y_axis_format	string	The Y Axis Format widget
y_axis_zero	N/A	Deprecated?

Note the y_axis_format is defined under various section for some charts.

Other

Field	Type	Notes
color_scheme	string

Unclassified

Field	Type	Notes
add_to_dash	N/A
code	N/A
collapsed_fieldsets	N/A
comparison type	N/A
country_fieldtype	N/A
default_filters	N/A
entity	N/A
expanded_slices	N/A
filter_immune_slice_fields	N/A
filter_immune_slices	N/A
flt_col_0	N/A
flt_col_1	N/A
flt_eq_0	N/A
flt_eq_1	N/A
flt_op_0	N/A
flt_op_1	N/A
goto_dash	N/A
import_time	N/A
label	N/A
linear_color_scheme	N/A
new_dashboard_name	N/A
new_slice_name	N/A
num_period_compare	N/A
period_ratio_type	N/A
perm	N/A
rdo_save	N/A
refresh_frequency	N/A
remote_id	N/A
resample_fillmethod	N/A
resample_how	N/A
rose_area_proportion	N/A
save_to_dashboard_id	N/A
schema	N/A
series	N/A
show_bubbles	N/A
slice_name	N/A
timed_refresh_immune_slices	N/A
userid	N/A