where절을 만드는 함수를 하드코딩 없이 개선해보자

개요

하드코딩이 확장성을 저해한다는 리뷰를 받아서 다시 생각해보기로 했다..
컬럼명을 하드코딩하는 것을 가리키는 것 같은데 컬러명을 변수명 그대로 받아내는 방법이 필요할 것 같다

test 01

let gender = ["male", "female"]
let scent = ["citrus", "fruity"]

// value값이 존재하면 "column IN (value)"를 반환하는 함수
const query = (column, value) => {
  if(!value){
    return "";
  }
  return `${column} IN ("${value.join("\", \"")}")`;
}

let queryCondition = [query("sc.name", scent), query("g.name", gender)].filter(el => el !== "");

// 배열queryCondition의 요소가 존재하면 "WHERE 요소 AND 요소"를 반환하는 함수
const where = (queryCondition) => {
  if(queryCondition.length === 0){
    return "";
  }  
  let query = "WHERE "  
  for(let i=0; i<queryCondition.length; i++){
    query += `${queryCondition[i]}`
    if(i === queryCondition.length-1 ){
      return query;
    }
    query += ` AND `
  }
}

console.log( where(queryCondition) )

test 02

const where = (gender, scent) => {
    if(!gender && !scent){
      return "";
    }else if(!gender){
      return `WHERE sc.name IN ("${scent.join("\", \"")}")`
    }else if(!scent){
      return `WHERE g.name IN ("${gender.join("\", \"")}")`
    }else{
      return `WHERE sc.name IN ("${scent.join("\",\"")}") AND g.name IN ("${gender.join("\", \"")}")`
    }  
}

let whereQuery = where(gender, scent)
console.log(whereQuery)

test 03

   const where = (gender, scent) => {
     if(!gender && !scent) return "";
     if(!gender)return `WHERE sc.name IN ('${scent.join("\', \'")}')`
     if(!scent) return `WHERE g.name IN ('${gender.join("\', \'")}')`
     return `WHERE sc.name IN ('${scent.join("\', \'")}') AND g.name IN ('${gender.join("\', \'")}')`
   }

최종

const getProducts = async (gender, scent, orderBy, offset, limitNum) => {
  const params ={gender, scent};
  const scentFilterBuilder = (value) => { 
    if(!value)return "";
    return `sc.name IN ('${  value.join("\', \'")  }')`; 
  }; 

  const genderFilterBuilder = (value) => { 
    if(!value)return "";
    return `g.name IN ('${  value.join("\', \'")  }')`; 
  }; 
  const makeProductQueryBuilders = (params) => { 
    const builderSet = { 
        "gender": genderFilterBuilder, 
        "scent": scentFilterBuilder, 
    }; 
    let whereClauses = Object.entries(params).map( ([key, value]) => builderSet[key](value) ); 
    whereClauses = whereClauses.filter(el => el !== '')
    return `WHERE ${whereClauses.join(' AND ')}`;
  }; 
  
  const orderByQuery = (orderBySelected) => {
    if(!orderBySelected){ return "";}
    return `ORDER BY ${orderBySelected}`;
  }
  const limitQuery = (limitNumSelected, offsetSelected) => {
    if(!limitNumSelected){ return "";}
    return `LIMIT ${limitNumSelected} ${offsetQuery(offsetSelected)}`;
  }
  const offsetQuery = (offsetSelected) => {
    if(!offsetSelected){ return "";}
    return `OFFSET ${offsetSelected}`;
  }
  let whereClause = makeProductQueryBuilders(params)
  let orderByClause = orderByQuery(orderBy);
  let limitClause = limitQuery(limitNum, offset);
  return await productDao.getProducts(whereClause, orderByClause, limitClause);
};