`@Tags` with empty values generates empty-string tags in Swagger output
Author: AleksaMCodeCreated Aug 24, 2026Updated Aug 25, 2026
When using @Tags with empty values (for example @Tags, @Tags ,, or mixed @Tags tag1, ,tag2), swag generates empty-string entries in the operation tags array (e.g. [""], ["", ""], ["tag1", "", "tag2"]) instead of filtering empties or treating it as untagged.
To Reproduce Steps to reproduce the behavior:
- Create a Go API project using
swag initandgin-swagger. - Add endpoints with these annotations:
- // @Tags
- // @Tags ,
- // @Tags tag1, ,tag2
- Run swag init to generate docs.
- Open generated swagger.json (or /swagger/doc.json) and inspect operation tags.
Example I've used to generated the screenshot output below:
func main() {
r := gin.Default()
r.GET("/tournaments/:id", getTournamentByID)
r.GET("/health", getHealth)
r.GET("/about", getAbout)
r.GET("/tags-comma-only", getTagsCommaOnly)
r.GET("/tags-mixed", getTagsMixed)
r.GET("/swagger/*any", ginSwagger.WrapHandler(swaggerfiles.Handler))
_ = r.Run(":8082")
}
// getTournamentByID godoc
// @Summary Get tournament by ID
// @Description Fake endpoint for local Swagger tag tests
// @Tags
// @Produce json
// @Param id path string true "Tournament ID"
// @Success 200 {object} map[string]any
// @Router /tournaments/{id} [get]
func getTournamentByID(c *gin.Context) {
id := c.Param("id")
c.JSON(http.StatusOK, gin.H{
"id": id,
"name": "Mock Tournament",
"status": "scheduled",
})
}
// getHealth godoc
// @Summary Health check
// @Description Reference endpoint with a normal tag
// @Tags reference
// @Produce json
// @Success 200 {object} map[string]any
// @Router /health [get]
func getHealth(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{
"status": "ok",
})
}
// getAbout godoc
// @Summary About endpoint
// @Description Endpoint without explicit tags annotation
// @Produce json
// @Success 200 {object} map[string]any
// @Router /about [get]
func getAbout(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{
"service": "gin-empty-tags",
"mode": "demo",
})
}
// getTagsCommaOnly godoc
// @Summary Tags comma-only endpoint
// @Description Endpoint using comma-only tags annotation
// @Tags ,
// @Produce json
// @Success 200 {object} map[string]any
// @Router /tags-comma-only [get]
func getTagsCommaOnly(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{
"case": "comma-only-tags",
})
}
// getTagsMixed godoc
// @Summary Tags mixed endpoint
// @Description Endpoint using mixed empty and non-empty tags annotation
// @Tags tag1, ,tag2
// @Produce json
// @Success 200 {object} map[string]any
// @Router /tags-mixed [get]
func getTagsMixed(c *gin.Context) {
c.JSON(http.StatusOK, gin.H{
"case": "mixed-tags",
})
}Expected behavior Empty tag tokens should be ignored. Examples:
- @Tags -> no tags (untagged operation)
- @Tags , -> no tags
- @Tags tag1, ,tag2 -> ["tag1", "tag2"]
Screenshots
Your swag version
1.16.6
Your go version
1.25.5
Desktop (please complete the following information):
- OS: Windows
- Browser: Firefox
- Version: -
Additional context
Output from doc.json:
{
"schemes": [],
"swagger": "2.0",
"host": "",
"basePath": "/",
"paths": {
"/about": {
"get": {
"description": "Endpoint without explicit tags annotation",
"produces": [
"application/json"
],
"summary": "About endpoint",
"responses": {
"200": {
"description": "OK",
"schema": {
"type": "object",
"additionalProperties": true
}
}
}
}
},
"/health": {
"get": {
"description": "Reference endpoint with a normal tag",
"produces": [
"application/json"
],
"tags": [
"reference"
],
"summary": "Health check",
"responses": {
"200": {
"description": "OK",
"schema": {
"type": "object",
"additionalProperties": true
}
}
}
}
},
"/tags-comma-only": {
"get": {
"description": "Endpoint using comma-only tags annotation",
"produces": [
"application/json"
],
"tags": [
"",
""
],
"summary": "Tags comma-only endpoint",
"responses": {
"200": {
"description": "OK",
"schema": {
"type": "object",
"additionalProperties": true
}
}
}
}
},
"/tags-mixed": {
"get": {
"description": "Endpoint using mixed empty and non-empty tags annotation",
"produces": [
"application/json"
],
"tags": [
"tag1",
"",
"tag2"
],
"summary": "Tags mixed endpoint",
"responses": {
"200": {
"description": "OK",
"schema": {
"type": "object",
"additionalProperties": true
}
}
}
}
},
"/tournaments/{id}": {
"get": {
"description": "Fake endpoint for local Swagger tag tests",
"produces": [
"application/json"
],
"tags": [
""
],
"summary": "Get tournament by ID",
"parameters": [
{
"type": "string",
"description": "Tournament ID",
"name": "id",
"in": "path",
"required": true
}
],
"responses": {
"200": {
"description": "OK",
"schema": {
"type": "object",
"additionalProperties": true
}
}
}
}
}
}
}Source: swaggo/swag