orm: fix select .. limit 1 . This case now returns an ?Row.

compiler/query.v

@@ -8,6 +8,12 @@ import strings
 
 // `db.select from User where id == 1 && nr_bookings > 0` 
 fn (p mut Parser) select_query(fn_ph int) string {
+	// NB: qprefix, p.sql_i, p.sql_params SHOULD be reset for each query,
+	// because we can have many queries in the _same_ scope.
+	qprefix := p.get_tmp().replace('tmp','sql') + '_'
+	p.sql_i = 0
+	p.sql_params = ''
+                                                  
 	mut q := 'select ' 
 	p.check(.key_select) 
 	n := p.check_name() 
@@ -73,36 +79,55 @@ fn (p mut Parser) select_query(fn_ph int) string {
 		p.is_sql = false 
 		limit := p.cgen.end_tmp() 
 		q += ' limit ' + limit 
-		// `limit 1` means we are getting `User`, not `[]User` 
+		// `limit 1` means we are getting `?User`, not `[]User` 
 		if limit.trim_space() == '1' { 
 			query_one = true 
 		} 
 	} 
 	println('sql query="$q"')
+	p.cgen.insert_before('// DEBUG_SQL prefix: $qprefix | fn_ph: $fn_ph | query: "$q" ')
+	
 	if n == 'count' {
 		p.cgen.set_placeholder(fn_ph, 'pg__DB_q_int(')
 		p.gen(', tos2("$q"))') 
 	} else { 
 		// Build an object, assign each field. 
 		tmp := p.get_tmp() 
-		mut obj_gen := strings.new_builder(100) 
+		mut obj_gen := strings.new_builder(300) 
 		for i, field in fields {
 			mut cast := '' 
 			if field.typ == 'int' {
 				cast = 'string_int' 
 			} 
-			obj_gen.writeln('$tmp . $field.name = $cast( *(string*)array__get(row.vals, $i) );')    
+			obj_gen.writeln('${qprefix}$tmp . $field.name = $cast( *(string*)array__get(${qprefix}row.vals, $i) );')
 		} 
 		// One object 
 		if query_one { 
+			mut params_gen := ''
+			params := p.sql_params.split(',')
+			for i, param in params {
+				params_gen += '${qprefix}params[$i] = int_str($param).str;'
+			}
 			p.cgen.insert_before('
 
-pg__Row row = pg__DB_exec_one(db, tos2("$q"));
+char* ${qprefix}params[$p.sql_i];
-$table_name $tmp; 
+$params_gen
+
+Option_${table_name} opt_${qprefix}$tmp;
+void* ${qprefix}res = PQexecParams(db.conn, "$q", $p.sql_i, 0, ${qprefix}params, 0, 0, 0)  ;
+array_pg__Row ${qprefix}rows = pg__res_to_rows ( ${qprefix}res ) ;
+Option_pg__Row opt_${qprefix}row = pg__rows_first_or_empty( ${qprefix}rows );
+if (! opt_${qprefix}row . ok ) {
+   opt_${qprefix}$tmp = v_error( opt_${qprefix}row . error );
+}else{
+   $table_name ${qprefix}$tmp;
+   pg__Row ${qprefix}row = *(pg__Row*) opt_${qprefix}row . data; 
 ${obj_gen.str()}
+   opt_${qprefix}$tmp = opt_ok( & ${qprefix}$tmp, sizeof($table_name) );
+}
 
 ')
-			p.cgen.resetln(tmp) 
+			p.cgen.resetln('opt_${qprefix}$tmp')
 		} 
 		// Array 
 		else {
@@ -110,32 +135,31 @@ ${obj_gen.str()}
 			mut params_gen := '' 
 			params := p.sql_params.split(',') 
 			for i, param in params {
-			params_gen += 'params[$i] = int_str($param).str;'  
+				params_gen += '${qprefix}params[$i] = int_str($param).str;'
 			}
-
+			p.cgen.insert_before('char* ${qprefix}params[$p.sql_i];
-		p.cgen.insert_before('char* params[$p.sql_i];
 $params_gen 
 
-void* res = PQexecParams(db.conn, "$q", $p.sql_i, 0, params, 0, 0, 0)  ; 
+void* ${qprefix}res = PQexecParams(db.conn, "$q", $p.sql_i, 0, ${qprefix}params, 0, 0, 0)  ;
-array_pg__Row rows = pg__res_to_rows(res); 
+array_pg__Row ${qprefix}rows = pg__res_to_rows(${qprefix}res);
 
 // TODO preallocate 
-array arr_$tmp = new_array(0, 0, sizeof($table_name));  
+array ${qprefix}arr_$tmp = new_array(0, 0, sizeof($table_name));
-for (int i = 0; i < rows.len; i++) { 
+for (int i = 0; i < ${qprefix}rows.len; i++) {
-	pg__Row row = *(pg__Row*)array__get(rows, i); 
+    pg__Row ${qprefix}row = *(pg__Row*)array__get(${qprefix}rows, i);
-	$table_name $tmp; 
+    $table_name ${qprefix}$tmp;
     ${obj_gen.str()} 
-	_PUSH(&arr_$tmp, $tmp, ${tmp}2, $table_name);  
+    _PUSH(&${qprefix}arr_$tmp, ${qprefix}$tmp, ${tmp}2, $table_name);
 } 
 ')
-		p.cgen.resetln('arr_$tmp') 
+			p.cgen.resetln('${qprefix}arr_$tmp')
 } 
 		 
 	} 
 	if n == 'count' {
 		return 'int' 
 	}	else if query_one {
-		return table_name 
+		return 'Option_$table_name'
 	}  else {
 		p.register_array('array_$table_name') 
 		return 'array_$table_name' 

vlib/builtin/int.v

@@ -48,7 +48,7 @@ pub fn (nn int) str() string {
 		return '0'
 	}
 	max := 16
-	mut buf := malloc(max)
+	mut buf := calloc(max)
 	mut len := 0
 	mut is_neg := false
 	if n < 0 {

vlib/pg/pg.v

@@ -29,6 +29,7 @@ pub:
   host string
   user string
   password string
+  dbname string
 }
 
 fn C.PQconnectdb(a byteptr) *C.PGconn
@@ -106,21 +107,22 @@ pub fn (db DB) exec(query string) []pg.Row {
 	return res_to_rows(res)
 }
 
-pub fn (db DB) exec_one(query string) pg.Row {
+fn rows_first_or_empty(rows []pg.Row) pg.Row? {
-	res := C.PQexec(db.conn, query.str)
-	e := string(C.PQerrorMessage(db.conn))
-	if e != '' {
-		println('pg exec error:')
-		println(e)
-		return Row{} 
-	}
-	rows := res_to_rows(res)
 	if rows.len == 0 {
-		return Row{} 
+		return error('no row')
 	} 
 	return rows[0]
 }
             
+pub fn (db DB) exec_one(query string) pg.Row? {
+	res := C.PQexec(db.conn, query.str)
+	e := string(C.PQerrorMessage(db.conn))
+	if e != '' {
+		return error('pg exec error: "$e"')
+	}
+	row := rows_first_or_empty( res_to_rows(res) )
+	return row
+}
 
 // 
 pub fn (db DB) exec_param2(query string, param, param2 string) []pg.Row {