Empty query result, no rows

[GuilhermeLessa]

When the query has no result, some error occurs inside the item(0) function and break code.
Else dont run.

Returning the promise without displaying error?
How to execute a code if the select returns empty?

db.executeSql('SELECT userValid ... "', [], function (r) {
        alert(1); //sucess!
        if (r.rows.item(0).userValid == '1') { //test empty result, stop code
          //home page 
          alert(2);
        } else {
           //login page
           alert(3);
        }
  }, function (error) {
      
 });

[brodycj]

In case of SELECT query which returns zero (0) rows I can think of the possible results:

• success with zero (0) rows: check if r.rows.length === 0
• error result

I will need to add a test case to be 100% sure on all platforms.

Testing, possible fix, and documentation needed for June 2018 release ref: #773

[GuilhermeLessa]

With verification length works fine.

 if (r.rows.length === 0) {
          //false
 } else {
          if (r.rows.item(0).valor == '1') {
            //true
          } else {
            //false
          }
}

Your repository support is the best. I wish good improvements to the next release. Thanks!

[brodycj]

Reopening for now, would like to keep this open until I get this in the test suite for all platforms and explicitly documented.

I would like to make another comment about the code above: it seems to me like the code assumes that there will never be more than 1 record that matches the SELECT statement. I would have added something else to ensure that this is always the case. Recommended: use constraints in CREATE TABLE. This is very common practice and there is plenty of documentation available including:

• https://www.tutorialspoint.com/sqlite/sqlite_constraints.htm
• https://www.tutorialspoint.com/sqlite/sqlite_unique.htm
• for reference: https://www.sqlite.org/lang_createtable.html

It would also be possible to check this after the fact, using assertion or error logging in case of r.rows.length > 1 (Sentry.io is highly recommended for logging internal errors).