Adding sort to filter

NOTES.md

@@ -33,6 +33,25 @@ BODY='{"title":"Black Panther","year":2018,"runtime":"134 mins","genres":["sci-f
 curl -X PUT -d "$BODY" http://0.0.0.0:5002/v1/movies/1
 ```
 
+## Sorting by items
+
+REMEMBER: you have to quote strings that contain & 
+
+```bash
+curl http://localhost:5002/v1/movies?genres=comedy&sort=-year
+```
+```text
+"time":"2026-02-08T11:35:42.782856326-05:00","level":"DEBUG","source":{"function":"main.(*application).listMoviesHandler","file":"/home/toor/workspace/pulley/cmd/api/handlers.go","line":247},"msg":"query params","qp":{"genres":["comedy"]}}
+```
+
+
+```bash
+curl "http://localhost:5002/v1/movies?genres=comedy&sort=-year"
+```
+```text
+{"time":"2026-02-08T11:38:52.253316749-05:00","level":"DEBUG","source":{"function":"main.(*application).listMoviesHandler","file":"/home/toor/workspace/pulley/cmd/api/handlers.go","line":247},"msg":"query params","qp":{"genres":["comedy"],"sort":["-year"]}}
+```
+
 ## Generating an Update Conflict
 
 We can try to use the xargs tool to submit multiple requests to our webserver. Hopefully this results in the 409 that we are looking to create.

cmd/api/main.go

@@ -92,7 +92,7 @@ func run(ctx context.Context, w io.Writer, args []string) error {
 		pool.Close()
 	}()
 
-	models := data.NewModels(pool)
+	models := data.NewModels(pool, logger)
 
 	app := application{config: cfg, logger: logger, models: models}
 

cmd/api/testutils.go

@@ -11,11 +11,10 @@ import (
 
 func newTestApplication(pool database.PgxIface) application {
 	cfg := config.ServiceConfig{Env: "test"}
-	mockModels := data.NewModels(pool)
 	// Discards log output from tests
 	// logger := slog.New(slog.NewTextHandler(io.Discard, nil))
 	logger := slog.New(slog.NewTextHandler(os.Stdout, &slog.HandlerOptions{Level: slog.LevelDebug, AddSource: true}))
-
+	mockModels := data.NewModels(pool, logger)
 	return application{config: cfg, logger: logger, models: mockModels}
 
 }

internal/data/filters.go

@@ -1,6 +1,10 @@
 package data
 
-import "git.runcible.io/learning/pulley/internal/validator"
+import (
+	"strings"
+
+	"git.runcible.io/learning/pulley/internal/validator"
+)
 
 type Filters struct {
 	Page         int
@@ -16,3 +20,24 @@ func ValidateFilters(v *validator.Validator, f Filters) {
 	v.Check(f.PageSize <= 100, "page_size", "must be a maximum of 100")
 	v.Check(validator.PermittedValue(f.Sort, f.SortSafelist...), "sort", "invalid sort value")
 }
+
+// sortColumn checks that the client-provided Sort field matches one of the entries in our safelist
+// and if it does, extract the column name from the Sort field.
+func (f Filters) sortColumn() string {
+	for _, safeValue := range f.SortSafelist {
+		if f.Sort == safeValue {
+			return strings.TrimPrefix(f.Sort, "-")
+		}
+	}
+	// ValidateFilters should have checked this, but we are extra careful of sql injection.
+	panic("unsafe sort parameter: " + f.Sort)
+}
+
+// sortDirection returns the sort direction depending on the prefix
+// character of the Sort field.
+func (f Filters) sortDirection() string {
+	if strings.HasPrefix(f.Sort, "-") {
+		return "DESC"
+	}
+	return "ASC"
+}

internal/data/models.go

@@ -2,6 +2,7 @@ package data
 
 import (
 	"errors"
+	"log/slog"
 
 	"git.runcible.io/learning/pulley/internal/database"
 )
@@ -16,8 +17,8 @@ type Models struct {
 	Movies MovieModel
 }
 
-func NewModels(pool database.PgxIface) *Models {
+func NewModels(pool database.PgxIface, logger *slog.Logger) *Models {
 	return &Models{
-		Movies: MovieModel{db: pool},
+		Movies: MovieModel{db: pool, logger: logger},
 	}
 }

internal/data/movies.go

@@ -3,6 +3,8 @@ package data
 import (
 	"context"
 	"errors"
+	"fmt"
+	"log/slog"
 	"time"
 
 	"git.runcible.io/learning/pulley/internal/database"
@@ -31,6 +33,7 @@ type Movie struct {
 
 type MovieModel struct {
 	db     database.PgxIface
+	logger *slog.Logger
 }
 
 func (m MovieModel) Insert(ctx context.Context, movie *Movie) error {
@@ -189,12 +192,19 @@ func (m MovieModel) GetAll(ctx context.Context, title string, genres []string, f
 	// example, the query term 'the' & 'club' will match rows which contain both lexemes
 	// 'the' and 'club'.
 
-	query := `
+	// 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`
+
+	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`, filters.sortColumn(), filters.sortDirection())
 
 	// ctx want some timeout for queries. When used in the handler the context passed should
 	// be the r.Context. Since cancel functions are inherited it will cancel on client
@@ -202,6 +212,8 @@ func (m MovieModel) GetAll(ctx context.Context, title string, genres []string, f
 	ctxTimeout, cancel := context.WithTimeout(ctx, 3*time.Second)
 	defer cancel()
 
+	m.logger.Debug(query)
+
 	rows, err := m.db.Query(ctxTimeout, query, title, genres)
 	if err != nil {
 		return nil, err