Allow a NULL tags property to be nil when read from the database (#…

…44)

This one's so tiny that it's minutiae, but as I was looking at the
null-ability of various job row fields today while implementing Ruby, I
realized that it doesn't really seem necessary to be marshaling a `NULL`
tags value to an empty `[]string{}` slice. In Go, `[]string{}` and
`[]string(nil)` are functionally identical in every way that I can think
of (`append` on `nil` works, `len` on `nil` works), so I think it makes
sense just to avoid the allocation and reflect what the database's
actual value is.

[1] https://go.dev/tour/moretypes/15

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Constants renamed so that adjectives like `Default` and `Min` become suffixes instead of prefixes. So for example, `DefaultFetchCooldown` becomes `FetchCooldownDefault`.
 - Rename `AttemptError.Num` to `AttemptError.Attempt` to better fit with the name of `JobRow.Attempt`.
 - Document `JobState`, `AttemptError`, and all fields its fields.
+- A `NULL` tags value read from a database job is left as `[]string(nil)` on `JobRow.Tags` rather than a zero-element slice of `[]string{}`. `append` and `len` both work on a `nil` slice, so this should be functionally identical.
 
 ## [0.0.6] - 2023-11-19
 

client_test.go

@@ -658,7 +658,7 @@ func Test_Client_Insert(t *testing.T) {
 		require.Equal(t, (&noOpArgs{}).Kind(), jobRow.Kind)
 		require.Equal(t, PriorityDefault, jobRow.Priority)
 		require.Equal(t, QueueDefault, jobRow.Queue)
-		require.Equal(t, []string{}, jobRow.Tags)
+		require.Equal(t, []string(nil), jobRow.Tags)
 	})
 
 	t.Run("WithInsertOpts", func(t *testing.T) {
@@ -755,7 +755,7 @@ func Test_Client_InsertTx(t *testing.T) {
 		require.Equal(t, (&noOpArgs{}).Kind(), jobRow.Kind)
 		require.Equal(t, PriorityDefault, jobRow.Priority)
 		require.Equal(t, QueueDefault, jobRow.Queue)
-		require.Equal(t, []string{}, jobRow.Tags)
+		require.Equal(t, []string(nil), jobRow.Tags)
 
 		// Job is not visible outside of the transaction.
 		_, err = bundle.queries.JobGetByID(ctx, client.driver.GetDBPool(), jobRow.ID)
@@ -2790,7 +2790,7 @@ func TestInsert(t *testing.T) {
 				require.Equal(1, insertedJob.Priority)
 				// Default comes from database now(), and we can't know the exact value:
 				require.WithinDuration(time.Now(), insertedJob.ScheduledAt, 2*time.Second)
-				require.Equal([]string{}, insertedJob.Tags)
+				require.Equal([]string(nil), insertedJob.Tags)
 				// require.Equal([]byte("{}"), insertedJob.metadata)
 			},
 		},

internal/dbsqlc/river_job_ext.go

@@ -6,10 +6,6 @@ import (
 )
 
 func JobRowFromInternal(internal *RiverJob) *rivertype.JobRow {
-	tags := internal.Tags
-	if tags == nil {
-		tags = []string{}
-	}
 	return &rivertype.JobRow{
 		ID:          internal.ID,
 		Attempt:     max(int(internal.Attempt), 0),
@@ -25,7 +21,7 @@ func JobRowFromInternal(internal *RiverJob) *rivertype.JobRow {
 		Queue:       internal.Queue,
 		ScheduledAt: internal.ScheduledAt.UTC(), // TODO(brandur): Very weird this is the only place a UTC conversion happens.
 		State:       rivertype.JobState(internal.State),
-		Tags:        tags,
+		Tags:        internal.Tags,
 
 		// metadata: internal.Metadata,
 	}