NodeJS implementation to generate condition for Query Builder used in frontend. eg: https://github.com/zebzhao/Angular-QueryBuilder, https://github.com/ukrbublik/react-awesome-query-builder

query_builder.js

let findAndOrCondition= (obj) => Object.entries(obj).filter(([key, value]) => key === 'condition' && value === 'and' || value === 'or');

const constructCondition = (conditionString, rule_object) => {
    if(findAndOrCondition(rule_object).length > 0) {
        conditionString.val += '('
        let rules = rule_object.rules
        console.log('rules', rules)
        for(var i=0; i<rules.length; i++) {
            let rule_obj = rules[i]
            if(findAndOrCondition(rule_obj).length > 0) {
                constructCondition(conditionString, rule_obj)
            } else {
                let condition = `field=${rule_obj.value}`
                conditionString.val += condition
            }
            if(i === rules.length - 1) continue
            conditionString.val += ` ${rule_object.condition} `
        }
        return conditionString.val += ')'  
    } 
}

let obj = {
    "condition": "or",
    "rules": [
        {
            "condition": "and",
            "rules": [
                {
                    "field_id": 6,
                    "condition": 2,
                    "value": 300000
                },
                {
                    "field_id": 2,
                    "condition": 1,
                    "value": "2021-10-27"
                }
            ]
        },
        {
            "field_id": 6,
            "condition": 2,
            "value": 500000
        }
    ]
}

console.log(constructCondition({ val : '' }, obj))