Add templating coalesce function (#4492)

internal/util/template/funcs.go

@@ -12,3 +12,14 @@ func truncateFrom(str, sep string) string {
 	before, _, _ := strings.Cut(str, sep)
 	return before
 }
+
+// coalesce will return the first non-empty string in the list of strings, and
+// an empty string if all parameters are empty.
+func coalesce(vals ...string) string {
+	for _, val := range vals {
+		if val != "" {
+			return val
+		}
+	}
+	return ""
+}

internal/util/template/generate.go

@@ -33,6 +33,7 @@ func New(ctx context.Context, raw string) (*Parsed, error) {
 		raw: raw,
 		funcMap: map[string]any{
 			"truncateFrom": truncateFrom,
+			"coalesce":     coalesce,
 		},
 	}
 

internal/util/template/generate_test.go

@@ -39,7 +39,7 @@ func TestErrors(t *testing.T) {
 	require.NotNil(parsed)
 	assert.Equal(ts, parsed.raw)
 	assert.NotNil(parsed.tmpl)
-	assert.Len(parsed.funcMap, 1)
+	assert.Len(parsed.funcMap, 2)
 
 	// Test out errors on the parsed value
 
@@ -102,6 +102,8 @@ func TestGenerate(t *testing.T) {
 {{ .Account.Subject }}
 {{ .Account.Email }}
 {{ truncateFrom .Account.Email "@" }}
+{{ coalesce "" .Account.LoginName .Account.Name }}
+{{ coalesce "" "" .Account.Name .Account.LoginName }}
 `)
 
 	parsed, err := New(ctx, raw)
@@ -128,6 +130,8 @@ accountLoginName
 accountSubject
 account@email.com
 account
+accountLoginName
+accountName
 `)
 
 	assert.Equal(exp, out)

internal/util/template/types.go

@@ -19,10 +19,11 @@ type Data struct {
 // request to be from a different auth method, in which case it may not match
 // what's in the Account struct.
 type User struct {
-	Id       *string
-	Name     *string
-	FullName *string
-	Email    *string
+	Id        *string
+	Name      *string
+	LoginName *string
+	FullName  *string
+	Email     *string
 }
 
 // Account contains account information. Not all fields will always be