mijms

import {get} from 'lodash'
let x = {a: 1, b:2}
// a and b is conditional key like if key == a
let hope = get(x, 'kkk', 'not exist');
// magic is just happen not exist is appear welcome lodash

mijms

//// exporting your index applying function
import * as Filters from './main';
export default function applyFilters(params={}, data, state=store.getState(), props={}){
    const action = get(Filters, params.key, (p, d)=>d);
    data = action(params, data, state, {applyFilters: applyFilters, ...props});
    
    if(params.then){
        data = applyFilters(params.then, data, state, props);
    }
    return data;

mijms

export const buildReducers = (name)=>{
    const handlers = {
        [`set_main_${name}`]: mainHandlers.set_main,
    };
    return {
        [name]: (state = {}, action)=>( get(handlers, action.type, d => d)(state, action))
    }
}

// buildReducer('app_name')