如何基于参数以更高效、更好的方式分析数据库表中的字符串？

Question

I have two databases which are hooked to two different backend application servers. Both the servers talk to one single web application. Now, one can simply change a url parameter on the UI to choose which service to communicate with ie, if you set serverUrl='abc' , it would point to server A with database A , and if you set serverUrl='cde' , it would point to server B with database B . I have workflow tests on the front end which are basically common for both the services. But the field names in the db A and db B are different. ie, lets say if I have a field name called as "webid" in db A , the same field name is called as " Webid " in db B and similarly there are more like " code " in db A is " CODE " in db B . So, instead of duplicating my tests, I simply created a function, where I simply check based on the serverUrl, if it's db A , return "code" else return " CODE ", and so on for all the field names in the database. So, in my tests, instead of simply creating the query with the normal fieldname , I pass in checkField("code") and it returns a string based on the condition ( serverUrl ) and executes the query.

The function is as follows:

function checkField(str: string) : string {
          let server = serverUrl === 'abc' ? true : false;
           switch (args[0].toLowerCase()) {
            case 'code':
                return serverUrl ? 'code' : 'CODE';
            case 'webid':
                return serverUrl ? 'webid' : 'Webid';
            case 'pkid':
                return serverUrl ? 'pkid' : 'PkId';
            case 'barcode':
                return serverUrl ? 'barcode' : 'Barcode';
            case 'price':
                return serverUrl ? 'price' : 'Price';
            case 'bestbefore':
                return serverUrl ? 'bestbefore' : 'BestBefore';
            case 'produce':
                return serverUrl ? 'produce' : 'Produce';
            case 'sales':
                return serverUrl ? 'sales' : 'Sales';
            case 'marketid':
                return serverUrl ? "marketid" : "MarketId";
            case 'regdate':
                return serverUrl ? "regdate" : "Regdate"; //and more fields
            default:
                return args[0]; 

}

So, I was wondering if there is a more elegant way to do this kind of comparison. Can we use static code analyzers here in anyway?[I am not really sure what they are] Any insights or pointers would be great. Thank you so much.

Answer 1

The insight would be that when serverUrl is truthy, you don't need the switch at all - you always return the same value that was switched upon. So don't do the test in every switch case , but do it once before that:

function checkField(str: string) : string {
    if (serverUrl === 'abc')
        return str.toLowerCase();
    else
        switch (str.toLowerCase()) {
            case 'code': return 'CODE';
            case 'webid': return 'Webid';
            case 'pkid': return 'PkId';
            case 'barcode': return 'Barcode';
            case 'price': return 'Price';
            case 'bestbefore': return 'BestBefore';
            case 'produce': return 'Produce';
            case 'sales': return 'Sales';
            case 'marketid': return "MarketId";
            case 'regdate': return "Regdate";
            //and more fields
            default: return str;
        }
}

Instead of the switch statement, you can also use an object literal or a Map as a lookup table.

Answer 2

Borrowing a bit from @Bergi's answer, I would create a mapping object to make it a little cleaner. Eg:

function checkField(str: string) : string {
    //create a mapping
    var myMapping = {
         'code'   : 'CODE',
         'webid'  : 'Webid',
         'pkid'   : 'PkId',
         'barcode': 'Barcode',
         //and more fields
    }

    if (serverUrl === 'abc') {
        return str.toLowerCase();
    } else {
        return myMapping[str.toLowerCase()] || str;
    }
}

This keeps the logic a little more separate from the mapping, so it feels cleaner to me. But that's a personal preference.

Answer 3

You can put all the values in a map.

function checkField(String str) {
    let map = new Map([["code", "CODE"], ["webid", "Webid"]]);
    if (serverUrl === 'abc')
        return str.toLowerCase();
    else    
        return map[str]
}