TemplateCache/customs: don't fail on missing keys (#538)

If 'customs' returns an error for missing keys on changes,
it's difficult to add a new custom key with unreleased changes pending
and a template that uses 'customs'.

Change 'customs' to yield an empty string for a missing custom key.
This matches the behavior of accessing the missing key directly
via `$change.Custom.Foo`.

Resolves #536

* Prepare release v1.13.1

Co-authored-by: Ronnie <miniscruff@hey.com>

.changes/v1.13.1.md

@@ -0,0 +1,5 @@
+## v1.13.1 on 2023-09-16
+
+### Fixed
+
+* [#536](https://github.com/miniscruff/changie/issues/536) customs template function returns an empty string instead of an error for missing keys.

CHANGELOG.md

@@ -6,6 +6,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html),
 and is generated by [itself](https://github.com/miniscruff/changie).
 
+## v1.13.1 on 2023-09-16
+
+### Fixed
+
+* [#536](https://github.com/miniscruff/changie/issues/536) customs template function returns an empty string instead of an error for missing keys.
+
 ## v1.13.0 on 2023-08-19
 
 ### Added

core/templatecache.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"fmt"
 	"io"
 	"text/template"
 	"time"
@@ -184,18 +183,14 @@ func (tc *TemplateCache) Times(changes []Change) ([]time.Time, error) {
 }
 
 // Customs will return all the values from the custom map by a key.
+// If a key is missing from a change, it will be an empty string.
 // example: yaml
 // format: "{{ customs .Changes \"Author\" }} authors"
 func (tc *TemplateCache) Customs(changes []Change, key string) ([]string, error) {
-	var ok bool
-
 	values := make([]string, len(changes))
 
 	for i, c := range changes {
-		values[i], ok = c.Custom[key]
-		if !ok {
-			return nil, fmt.Errorf("missing custom key: '%v'", key)
-		}
+		values[i] = c.Custom[key]
 	}
 
 	return values, nil

core/templatecache_test.go

@@ -146,6 +146,22 @@ func TestCanGetCustoms(t *testing.T) {
 	then.Equals(t, "[miniscruff rocktavious emmyoop] authors", builder.String())
 }
 
+func TestCanGetCustomsMissingKey(t *testing.T) {
+	cache := NewTemplateCache()
+	builder := &strings.Builder{}
+	data := BatchData{
+		Changes: []Change{
+			{Custom: map[string]string{"Author": "miniscruff"}},
+			{Custom: map[string]string{"NotAuthor": "rocktavious"}},
+			{Custom: map[string]string{"Author": "emmyoop"}},
+		},
+	}
+
+	err := cache.Execute("{{ customs .Changes \"Author\" | compact }} authors", builder, data)
+	then.Nil(t, err)
+	then.Equals(t, "[miniscruff emmyoop] authors", builder.String())
+}
+
 func TestErrorBadTemplate(t *testing.T) {
 	cache := NewTemplateCache()
 	_, err := cache.Load("{{...___..__}}")
@@ -169,17 +185,3 @@ func TestErrorBadExecute(t *testing.T) {
 	then.NotNil(t, err)
 	then.Equals(t, builder.Len(), 0)
 }
-
-func TestErrorMissingKey(t *testing.T) {
-	cache := NewTemplateCache()
-	builder := &strings.Builder{}
-	data := BatchData{
-		Changes: []Change{
-			{Custom: map[string]string{"Author": "miniscruff"}},
-		},
-	}
-
-	err := cache.Execute("{{ customs .Changes \"MissingKey\" }}", builder, data)
-	then.NotNil(t, err)
-	then.Equals(t, builder.Len(), 0)
-}

docs/config.toml

@@ -46,7 +46,7 @@ summaryLength = 30
   ]
   enable_anchor_link = true
   issues_url = 'https://github.com/miniscruff/changie/issues/new'
-  version = 'v1.13.0'
+  version = 'v1.13.1'
 
   [params.homepage_meta_tags]
     meta_description = "Changie is a file based changelog management tool."

docs/static/version.json

@@ -1,3 +1,3 @@
 {
-    "latest": "v1.13.0"
+    "latest": "v1.13.1"
 }