Create a conditional filter in model using API

I am trying to update my Model file with a conditional filter using the api. But I don’t see the option to add the conditional filter in api body.
Here’s what I would like to add in the model file :-

conditionally_filter: {
filters: {
field: timestamp_time
value: “last 1 days”
}
unless: [timestamp_date, timestamp_time, timestamp_year, timestamp_month]
}

The 3.1 api “/LookmlModel/update_lookml_model” doesn’t seem to support this.
how can I add the conditional_filter using an api ?

The Looker API doesn’t actually support changing your LookML code, as a general rule. Since LookML is checked into git, you can programmatically edit your code in Github! There’s an API for contents: https://developer.github.com/v3/repos/contents/

Give that a whirl and see if that meets your needs.