Fixed issue where getColumnNames() returned an empty array if SELECT … (#412)

* Fixed issue where getColumnNames() returned an empty array if SELECT query returned 0 rows.

* Fixed line length issue with last commit.

* More eslint fixes

Author: cpainterwakefield

src/api.js

@@ -112,6 +112,11 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
     );
     var sqlite3_step = cwrap("sqlite3_step", "number", ["number"]);
     var sqlite3_errmsg = cwrap("sqlite3_errmsg", "string", ["number"]);
+    var sqlite3_column_count = cwrap(
+        "sqlite3_column_count",
+        "number",
+        ["number"]
+    );
     var sqlite3_data_count = cwrap("sqlite3_data_count", "number", ["number"]);
     var sqlite3_column_double = cwrap(
         "sqlite3_column_double",
@@ -423,7 +428,7 @@ Module["onRuntimeInitialized"] = function onRuntimeInitialized() {
         var results1;
         results1 = [];
         i = 0;
-        ref = sqlite3_data_count(this.stmt);
+        ref = sqlite3_column_count(this.stmt);
         while (i < ref) {
             results1.push(sqlite3_column_name(this.stmt, i));
             i += 1;

src/exported_functions.json

@@ -13,6 +13,7 @@
 "_sqlite3_bind_int",
 "_sqlite3_bind_parameter_index",
 "_sqlite3_step",
+"_sqlite3_column_count",
 "_sqlite3_data_count",
 "_sqlite3_column_double",
 "_sqlite3_column_text",

test/test_statement.js

@@ -37,6 +37,10 @@ exports.test = function(sql, assert){
     assert.deepEqual(res, {nbr:5, str:'粵語😄', no_value:null}, "Statement.getAsObject()");
     stmt.free();
 
+    // getColumnNames() should work even if query returns no data 
+    stmt = db.prepare("SELECT * FROM data WHERE nbr = -1");
+    assert.deepEqual(stmt.getColumnNames(), ['nbr','str','no_value'], 'Statement.GetColumnNames()');
+    stmt.free();
 
     stmt = db.prepare("SELECT str FROM data WHERE str=?");
     assert.deepEqual(stmt.getAsObject(['粵語😄']), {'str':'粵語😄'}, "UTF8 support in prepared statements");