ch9.8

cmd/api/movies.go

@@ -198,13 +198,13 @@ func (app *application) listMoviesHandler(w http.ResponseWriter, r *http.Request
 		return
 	}
 
-	movies, err := app.models.Movies.GetAll(input.Title, input.Genres, input.Filters)
+	movies, metadata, err := app.models.Movies.GetAll(input.Title, input.Genres, input.Filters)
 	if err != nil {
 		app.serverErrorResponse(w, r, err)
 		return
 	}
 
-	err = app.writeJSON(w, http.StatusOK, envelope{"movies": movies}, nil)
+	err = app.writeJSON(w, http.StatusOK, envelope{"movies": movies, "metadata": metadata}, nil)
 	if err != nil {
 		app.serverErrorResponse(w, r, err)
 	}

internal/data/filters.go

@@ -1,6 +1,7 @@
 package data
 
 import (
+	"math"
 	"strings"
 
 	"gitea.local.lab/Lbenedar/greenlight/internal/validator"
@@ -13,6 +14,28 @@ type Filters struct {
 	SortSafelist []string
 }
 
+type Metadata struct {
+	CurrentPage  int `json:"current_page,omitempty"`
+	PageSize     int `json:"page_size,omitempty"`
+	FirstPage    int `json:"first_page,omitempty"`
+	LastPage     int `json:"last_page,omitempty"`
+	TotalRecords int `json:"total_records,omitempty"`
+}
+
+func calculateMetadata(totalRecords, page, pageSize int) Metadata {
+	if totalRecords == 0 {
+		return Metadata{}
+	}
+
+	return Metadata{
+		CurrentPage:  page,
+		PageSize:     pageSize,
+		FirstPage:    1,
+		LastPage:     int(math.Ceil(float64(totalRecords) / float64(pageSize))),
+		TotalRecords: totalRecords,
+	}
+}
+
 func ValidateFilters(v *validator.Validator, f Filters) {
 	v.Check(f.Page > 0, "page", "must be greater than zero")
 	v.Check(f.Page <= 10_000_000, "page", "must be a maximum of 10 million")

internal/data/models.go

@@ -16,7 +16,7 @@ type Models struct {
 		Get(id int64) (*Movie, error)
 		Update(movie *Movie) error
 		Delete(id int64) error
-		GetAll(title string, genres []string, filter Filters) ([]*Movie, error)
+		GetAll(title string, genres []string, filter Filters) ([]*Movie, Metadata, error)
 	}
 }
 

internal/data/movies.go

@@ -135,9 +135,9 @@ func (m MovieModel) Delete(id int64) error {
 	return nil
 }
 
-func (m MovieModel) GetAll(title string, genres []string, filter Filters) ([]*Movie, error) {
+func (m MovieModel) GetAll(title string, genres []string, filter Filters) ([]*Movie, Metadata, error) {
 	query := fmt.Sprintf(`
-		SELECT id, created_at, title, year, runtime, genres, version
+		SELECT count(*) over(), 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 = '{}')
@@ -147,18 +147,22 @@ func (m MovieModel) GetAll(title string, genres []string, filter Filters) ([]*Mo
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 	defer cancel()
 
-	rows, err := m.DB.QueryContext(ctx, query, title, pq.Array(genres), filter.limit(), filter.offset())
+	args := []any{title, pq.Array(genres), filter.limit(), filter.offset()}
+
+	rows, err := m.DB.QueryContext(ctx, query, args...)
 	if err != nil {
-		return nil, err
+		return nil, Metadata{}, err
 	}
 	defer rows.Close()
 
+	totalRecords := 0
 	movies := []*Movie{}
 
 	for rows.Next() {
 		var movie Movie
 
 		err := rows.Scan(
+			&totalRecords,
 			&movie.ID,
 			&movie.CreatedAt,
 			&movie.Title,
@@ -168,16 +172,18 @@ func (m MovieModel) GetAll(title string, genres []string, filter Filters) ([]*Mo
 			&movie.Version,
 		)
 		if err != nil {
-			return nil, err
+			return nil, Metadata{}, err
 		}
 		movies = append(movies, &movie)
 	}
 
 	if err = rows.Err(); err != nil {
-		return nil, err
+		return nil, Metadata{}, err
 	}
 
-	return movies, nil
+	metadata := calculateMetadata(totalRecords, filter.Page, filter.PageSize)
+
+	return movies, metadata, nil
 }
 
 type MockMovieModel struct{}
@@ -198,8 +204,8 @@ func (m MockMovieModel) Delete(id int64) error {
 	return nil
 }
 
-func (m MockMovieModel) GetAll(title string, genres []string, filter Filters) ([]*Movie, error) {
+func (m MockMovieModel) GetAll(title string, genres []string, filter Filters) ([]*Movie, Metadata, error) {
-	return nil, nil
+	return nil, Metadata{}, nil
 }
 
 func ValidateMovie(v *validator.Validator, movie *Movie) {