Populating tables with a single call to make for all keys

Populating tables with a single call to make for all keys

I'm working on a pipeline to extract LFP from raw data for a subset of channels. I want to do the filtering of the raw data in a single call to the make function (e.g. filter many channels at once) but I want to be able to have an entry in the LFP table for each channel so that that channel can be selected for subsequent analyses easily.  

The relevant schema are 
Raw - one entry per channel, but data stored in single NWB object
LFPElectrode - one entry per channel indicating whether that Electrode should be used for LFP
LFP - the computed table with the LFP

Right now I just have the LFP schema print out the key that was sent in, and when I set electrodes 1, 2, and 3 to be used for LFP in the LFPElectrode table, and then call

common_ephys.LFP.populate()

I get

LFP key:
{'nwb_file_name': '/data/nwb_builder_test_data/beans20190718s1.nwb', 'electrode_group_name': 'electrode group 0', 'electrode_id': 1}
LFP key:
{'nwb_file_name': '/data/nwb_builder_test_data/beans20190718s1.nwb', 'electrode_group_name': 'electrode group 0', 'electrode_id': 2}
LFP key:
{'nwb_file_name': '/data/nwb_builder_test_data/beans20190718s1.nwb', 'electrode_group_name': 'electrode group 0', 'electrode_id': 3}

What I want is a list of keys so I can do the filtering all at once.

Is there a way to do that?