Adding sorting lists.

internal/data/movies.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"fmt"
 	"github.com/lib/pq"
 	"time"
 
@@ -197,13 +198,14 @@ func (m MovieModel) GetAll(title string, genres []string, filters Filters) ([]*M
 	// Construct the SQL query to retrieve all movie records.
 	// to_tsvector('simple', title) transforms 'The Breakfast Club' into 'breakfast' 'club' 'the'. The 'simple' parameter's value is the configuration.
 	// plainto_tsquery('simple', $1) takes a search value and turns it into a formatted query term that PostgreSQL full-text search can understand. As an example : "The Club" would result in the query term 'the' & 'club'
-	// The @@ operator is the matches operator. To continue the example, the query term 'the' & 'club' will match rows which contain both lexemes 'the' and 'club'.
-	query := `
+	// The @@ operator is the matches' operator. To continue the example, the query term 'the' & 'club' will match rows which contain both lexemes 'the' and 'club'.
+	// Add an ORDER BY clause and interpolate the sort column and direction. Importantly, notice that we also include a secondary sort on the movie ID to ensure a consistent ordering.
+	query := fmt.Sprintf(`
 		SELECT id, created_at, title, year, runtime, genres, version
 		FROM movies
 		WHERE (to_tsvector('simple', title) @@ plainto_tsquery('simple', $1) OR $1 = '')
 		AND (genres @> $2 OR $2 = '{}')
-		ORDER BY id`
+		ORDER BY %s %s, id ASC`, filters.sortColumn(), filters.sortDirection())
 
 	// Create a context with a 3-second timeout
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
@@ -219,7 +221,7 @@ func (m MovieModel) GetAll(title string, genres []string, filters Filters) ([]*M
 	defer rows.Close()
 
 	// Initialize an empty slice to hold the movie data.
-	movies := []*Movie{}
+	var movies []*Movie
 
 	// Use rows.Next to iterate through the rows in the resultset.
 	for rows.Next() {