Comparing strings with contents of columns

Question

I wrote the following lines of code to compare some strings with contents of columns (string) in SQLite database:

void PaymentTransaction::setAttributesBySqliteStmt(sqlite3_stmt * statement)
{
 ZF_LOGD("setAttributesBySqliteStmt\n");
 int columnCnt = sqlite3_column_count(statement);
 for (int i = 0; i < columnCnt; i++) {
 if (strcmp("id", sqlite3_column_name(statement, i)) == 0)
 id = sqlite3_column_int(statement, i);
 else if (strcmp("gas_station_id", sqlite3_column_name(statement, i)) == 0)
 gas_station_id = sqlite3_column_int(statement, i);
 else if (strcmp("nozzle_id", sqlite3_column_name(statement, i)) == 0)
 nozzle_id = sqlite3_column_int(statement, i);
 ................
 //SAME CODES FOR OTHER COLUMNS 
 ................
 else {
 ZF_LOGW("Invalid column name(%s) in table name Transaction",
 sqlite3_column_name(statement, i));
 }
 }
 }
 void PaymentTransaction::bindValueToSqliteStmt(sqlite3_stmt* statement)
 {
int paramCnt = sqlite3_bind_parameter_count(statement);
for (int i = 1; i <= paramCnt; i++) {
 if (i == sqlite3_bind_parameter_index(statement, "@id"))
 sqlite3_bind_int(statement, i, id);
 else if (i == sqlite3_bind_parameter_index(statement, "@gas_station_id"))
 sqlite3_bind_int(statement, i, gas_station_id);
 else if (i == sqlite3_bind_parameter_index(statement, "@nozzle_id"))
 sqlite3_bind_int(statement, i, nozzle_id);
 else if ............
 //SAME CODES FOR OTHER COLUMNS 
 ..................
 else {
 ZF_LOGW("Invalid param name(%s) in table name Transaction",
 sqlite3_bind_parameter_name(statement, i));
 }
 }
}

Since there are 30 columns in total, there are lots of if else statements and I was wondering whether there is better/shorter way of writing these lines of code?

• BCdotWEB: As we all want to make our code more efficient or improve it in one way or another, try to write a title that summarizes what your code does, not what you want to get out of a review. Please see How to get the best value out of Code Review - Asking Questions for guidance on writing good question titles.
• mOna: @BCdotWEB: thanks for the guide. It was a bit difficult for me to explain briefly in the tile what I need.. but I tried and hope it is better now.
• BCdotWEB: @mOna You didn't change the title, so I'm not sure what your comment refers to. Also, if you have multiple accounts, please request a merge so you can edit your own posts without needing approval.
• 301_Moved_Permanently: @BCdotWEB For the title: codereview.stackexchange.com/review/suggested-edits/64168 and codereview.stackexchange.com/review/suggested-edits/64171
• miscco: I think it would be necessary to show your PaymentTransaction class. I could immagine, that you can utilize a map based approach, where you use the string as a keyword and write directly into the data field. However this only works if everything has the same type otherwise it will get more complicated.

Answer 1

The obvious approach here would be to use a map or unordered_map to convert from a column name to a pointer (or reference) to the actual column. This will typically reduce the line count by about 2:1. More importantly, however, it makes most of that simple initialization, and the code that executes at run time is about 3 lines or so. An implementation would look something like this:

struct PaymentTransaction {
 int id;
 int gas_station_id;
 int nozzle_id;
 // more members here
public:
 void setAttributes(sqlite3_statement const *);
};
void PaymentTransaction::setAttributes(sqlite3_statement const *statement) {
 for (int i = 0; i < statement->sqlite3_column_count(); i++) {
 std::string name = sqlite3_column_name(statement, i);
 static const std::map<std::string, int &> int_members{
 { "id", id},
 {"gas_station_id", gas_station_id},
 {"nozzle_id", nozzle_id}
 // ...
 };
 auto pos = int_members.find(name);
 if (pos != int_members.end()) {
 pos->second = sqlite3_column_int(statement, i);
 }
 }
 // Possibly similar code for members of other types
}

Note that this requires a separate map for each type of column (integer vs. floating point vs. string) but can have a single map for all the columns of one type.

You could separate the map from the function, and make the function a template to avoid duplicating that code (but this may be more trouble than it's worth, depending on how many types you need to deal with--all you've shown are ints, but I don't know how accurately that reflects you real use.

• mOna: Thanks a lot Jerry for your detailed answer. There are 30 columns and all of them (except two columns that are VARCHAR) are INT.