A Data Expression could take care of that for you. If you reshaped the data to have a "month" field separate from its date/time field, you could then use that as a category. We can use one of the functions that utilizes SQL to get that calculated field into our output FeatureSet.
It might look something like this:
var fields = ['fields', 'you', 'need']
var fs = FeatureSetByPortalItem(
Portal('your portal url'),
'itemid of service',
0, // or whatever layer index your specific layer is at
fields,
false
)
// convert list of fields into array of dicts that Distinct can use
var field_dicts = []
for (var f in fields){
Push(
field_dicts,
{name: fields[f], expression: fields[f]}
)
}
// push our calculated date field into array
Push(
field_dicts,
{name: 'the_month', expression: 'EXTRACT(MONTH FROM date_field)'}
)
// use field dicts to return featureset with added field
return Distinct(fs, field_dicts)
And just to explain that a bit, the FeatureSetByPortalItem function takes an array of field names as a parameter. In order to use SQL in Distinct, however, we need an array of dictionaries with a name and expression. If we omit any of our input fields from that array of dictionaries, it will be dropped from the output.
You could just type out the whole array of dicts by hand, but I don't know how many fields you want in your FeatureSet. This method of constructing the array of dicts from the array of field names can accommodate any number of fields listed in the fields array without any change.
- Josh Carlson
Kendall County GIS
