feat: get movies, url parametes parsing and validating, sql exeme querying

projects/greenlight/internal/data/movies.go

@@ -1,6 +1,7 @@
 package data
 
 import (
+	"context"
 	"database/sql"
 	"errors"
 	"time"
@@ -14,6 +15,69 @@ type MovieModel struct {
 	DB *sql.DB
 }
 
+// Create a new GetAll() method which returns a slice of movies. Although we're not
+// using them right now, we've set this up to accept the various filter parameters as
+// arguments.
+func (m MovieModel) GetAll(title string, genres []string, filters Filters) ([]*Movie, error) {
+	// Use full-text search for the title filter.
+	query := `
+        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`
+
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	// Use QueryContext() to execute the query. This returns a sql.Rows resultset
+	// containing the result.
+	rows, err := m.DB.QueryContext(ctx, query, title, pq.Array(genres))
+	if err != nil {
+		return nil, err
+	}
+
+	// Importantly, defer a call to rows.Close() to ensure that the resultset is closed
+	// before GetAll() returns.
+	defer rows.Close()
+
+	// Initialize an empty slice to hold the movie data.
+	movies := []*Movie{}
+
+	// Use rows.Next to iterate through the rows in the resultset.
+	for rows.Next() {
+		// Initialize an empty Movie struct to hold the data for an individual movie.
+		var movie Movie
+
+		// Scan the values from the row into the Movie struct. Again, note that we're
+		// using the pq.Array() adapter on the genres field here.
+		err := rows.Scan(
+			&movie.ID,
+			&movie.CreatedAt,
+			&movie.Title,
+			&movie.Year,
+			&movie.Runtime,
+			pq.Array(&movie.Genres),
+			&movie.Version,
+		)
+		if err != nil {
+			return nil, err
+		}
+
+		// Add the Movie struct to the slice.
+		movies = append(movies, &movie)
+	}
+
+	// When the rows.Next() loop has finished, call rows.Err() to retrieve any error
+	// that was encountered during the iteration.
+	if err = rows.Err(); err != nil {
+		return nil, err
+	}
+
+	// If everything went OK, then return the slice of movies.
+	return movies, nil
+}
+
 // Add a placeholder method for inserting a new record in the movies table.
 func (m MovieModel) Insert(movie *Movie) error {
 	// Define the SQL query for inserting a new record in the movies table and returning
@@ -28,10 +92,14 @@ func (m MovieModel) Insert(movie *Movie) error {
 	// make it nice and clear *what values are being used where* in the query.
 	args := []interface{}{movie.Title, movie.Year, movie.Runtime, pq.Array(movie.Genres)}
 
+	// Create a context with a 3-second timeout.
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
 	// Use the QueryRow() method to execute the SQL query on our connection pool,
 	// passing in the args slice as a variadic parameter and scanning the system-
 	// generated id, created_at and version values into the movie struct.
-	return m.DB.QueryRow(query, args...).Scan(&movie.ID, &movie.CreatedAt, &movie.Version)
+	return m.DB.QueryRowContext(ctx, query, args...).Scan(&movie.ID, &movie.CreatedAt, &movie.Version)
 }
 
 func (m MovieModel) Get(id int64) (*Movie, error) {
@@ -52,11 +120,20 @@ func (m MovieModel) Get(id int64) (*Movie, error) {
 	// Declare a Movie struct to hold the data returned by the query.
 	var movie Movie
 
+	// Use the context.WithTimeout() function to create a context.Context which carries a
+	// 3-second timeout deadline. Note that we're using the empty context.Background()
+	// as the 'parent' context.
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+
+	// Importantly, use defer to make sure that we cancel the context before the Get()
+	// method returns.
+	defer cancel()
+
 	// Execute the query using the QueryRow() method, passing in the provided id value
 	// as a placeholder parameter, and scan the response data into the fields of the
 	// Movie struct. Importantly, notice that we need to convert the scan target for the
 	// genres column using the pq.Array() adapter function again.
-	err := m.DB.QueryRow(query, id).Scan(
+	err := m.DB.QueryRowContext(ctx, query, id).Scan(
 		&movie.ID,
 		&movie.CreatedAt,
 		&movie.Title,
@@ -98,10 +175,13 @@ func (m MovieModel) Update(movie *Movie) error {
 		movie.ID,
 		movie.Version,
 	}
+	// Create a context with a 3-second timeout.
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
 
 	// Use the QueryRow() method to execute the query, passing in the args slice as a
 	// variadic parameter and scanning the new version value into the movie struct.
-	err := m.DB.QueryRow(query, args...).Scan(&movie.Version)
+	err := m.DB.QueryRowContext(ctx, query, args...).Scan(&movie.Version)
 	if err != nil {
 		switch {
 		case errors.Is(err, sql.ErrNoRows):
@@ -124,11 +204,14 @@ func (m MovieModel) Delete(id int64) error {
 	query := `
         DELETE FROM movies
         WHERE id = $1`
+	// Create a context with a 3-second timeout.
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
 
 	// Execute the SQL query using the Exec() method, passing in the id variable as
 	// the value for the placeholder parameter. The Exec() method returns a sql.Result
 	// object.
-	result, err := m.DB.Exec(query, id)
+	result, err := m.DB.ExecContext(ctx, query, id)
 	if err != nil {
 		return err
 	}