feat(embed): Implement template loading from embedded filesystem (#48)

* Implement template loading from fs.FS

* Use os.DirFS instead of embed.FS for tests

* Remove go versions 1.14 and 1.15 from test workflow

---------

Co-authored-by: Bo-Yi Wu <appleboy.tw@gmail.com>

dynamic.go

@@ -3,6 +3,7 @@ package multitemplate
 import (
 	"fmt"
 	"html/template"
+	"io/fs"
 	"path/filepath"
 
 	"github.com/gin-gonic/gin"
@@ -39,6 +40,7 @@ const (
 	templateType builderType = iota
 	filesTemplateType
 	globTemplateType
+	fsTemplateType
 	stringTemplateType
 	stringFuncTemplateType
 	filesFuncTemplateType
@@ -51,6 +53,7 @@ type templateBuilder struct {
 	templateName    string
 	files           []string
 	glob            string
+	fsys            fs.FS
 	templateString  string
 	funcMap         template.FuncMap
 	templateStrings []string
@@ -64,6 +67,8 @@ func (tb templateBuilder) buildTemplate() *template.Template {
 		return template.Must(template.ParseFiles(tb.files...))
 	case globTemplateType:
 		return template.Must(template.ParseGlob(tb.glob))
+	case fsTemplateType:
+		return template.Must(template.ParseFS(tb.fsys, tb.files...))
 	case stringTemplateType:
 		return template.Must(template.New(tb.templateName).Parse(tb.templateString))
 	case stringFuncTemplateType:
@@ -108,6 +113,13 @@ func (r DynamicRender) AddFromGlob(name, glob string) *template.Template {
 	return builder.buildTemplate()
 }
 
+func (r DynamicRender) AddFromFS(name string, fsys fs.FS, files ...string) *template.Template {
+	builder := &templateBuilder{templateName: name, fsys: fsys, files: files}
+	builder.buildType = fsTemplateType
+	r[name] = builder
+	return builder.buildTemplate()
+}
+
 // AddFromString supply add template from strings
 func (r DynamicRender) AddFromString(name, templateString string) *template.Template {
 	builder := &templateBuilder{templateName: name, templateString: templateString}

dynamic_test.go

@@ -2,6 +2,7 @@ package multitemplate
 
 import (
 	"html/template"
+	"os"
 	"testing"
 
 	"github.com/gin-gonic/gin"
@@ -22,6 +23,13 @@ func createFromGlobDynamic() Renderer {
 	return r
 }
 
+func createFromFSDynamic() Render {
+	r := New()
+	r.AddFromFS("index", os.DirFS("."), "tests/base.html", "tests/article.html")
+
+	return r
+}
+
 func createFromStringDynamic() Renderer {
 	r := NewRenderer()
 	r.AddFromString("index", "Welcome to {{ .name }} template")
@@ -90,6 +98,20 @@ func TestAddFromGlobDynamic(t *testing.T) {
 	assert.Equal(t, "<p>Test Multiple Template</p>\nHi, this is login template\n", w.Body.String())
 }
 
+func TestAddFromFSDynamic(t *testing.T) {
+	router := gin.New()
+	router.HTMLRender = createFromFSDynamic()
+	router.GET("/", func(c *gin.Context) {
+		c.HTML(200, "index", gin.H{
+			"title": "Test Multiple Template",
+		})
+	})
+
+	w := performRequest(router, "GET", "/")
+	assert.Equal(t, 200, w.Code)
+	assert.Equal(t, "<p>Test Multiple Template</p>\nHi, this is article template\n", w.Body.String())
+}
+
 func TestAddFromStringDynamic(t *testing.T) {
 	router := gin.New()
 	router.HTMLRender = createFromStringDynamic()

multitemplate.go

@@ -3,6 +3,7 @@ package multitemplate
 import (
 	"fmt"
 	"html/template"
+	"io/fs"
 	"path/filepath"
 
 	"github.com/gin-gonic/gin/render"
@@ -49,6 +50,13 @@ func (r Render) AddFromGlob(name, glob string) *template.Template {
 	return tmpl
 }
 
+// AddFromFS supply add template from fs.FS (e.g. embed.FS)
+func (r Render) AddFromFS(name string, fsys fs.FS, files ...string) *template.Template {
+	tmpl := template.Must(template.ParseFS(fsys, files...))
+	r.Add(name, tmpl)
+	return tmpl
+}
+
 // AddFromString supply add template from strings
 func (r Render) AddFromString(name, templateString string) *template.Template {
 	tmpl := template.Must(template.New(name).Parse(templateString))

multitemplate_test.go

@@ -5,6 +5,7 @@ import (
 	"html/template"
 	"net/http"
 	"net/http/httptest"
+	"os"
 	"testing"
 
 	"github.com/gin-gonic/gin"
@@ -32,6 +33,13 @@ func createFromGlob() Render {
 	return r
 }
 
+func createFromFS() Render {
+	r := New()
+	r.AddFromFS("index", os.DirFS("."), "tests/base.html", "tests/article.html")
+
+	return r
+}
+
 func createFromString() Render {
 	r := New()
 	r.AddFromString("index", "Welcome to {{ .name }} template")
@@ -93,6 +101,20 @@ func TestAddFromGlob(t *testing.T) {
 	assert.Equal(t, "<p>Test Multiple Template</p>\nHi, this is login template\n", w.Body.String())
 }
 
+func TestAddFromFS(t *testing.T) {
+	router := gin.New()
+	router.HTMLRender = createFromFS()
+	router.GET("/", func(c *gin.Context) {
+		c.HTML(200, "index", gin.H{
+			"title": "Test Multiple Template",
+		})
+	})
+
+	w := performRequest(router, "GET", "/")
+	assert.Equal(t, 200, w.Code)
+	assert.Equal(t, "<p>Test Multiple Template</p>\nHi, this is article template\n", w.Body.String())
+}
+
 func TestAddFromString(t *testing.T) {
 	router := gin.New()
 	router.HTMLRender = createFromString()

renderer.go

@@ -2,6 +2,7 @@ package multitemplate
 
 import (
 	"html/template"
+	"io/fs"
 
 	"github.com/gin-gonic/gin/render"
 )
@@ -15,6 +16,7 @@ type Renderer interface {
 	Add(name string, tmpl *template.Template)
 	AddFromFiles(name string, files ...string) *template.Template
 	AddFromGlob(name, glob string) *template.Template
+	AddFromFS(name string, fsys fs.FS, files ...string) *template.Template
 	AddFromString(name, templateString string) *template.Template
 	AddFromStringsFuncs(name string, funcMap template.FuncMap, templateStrings ...string) *template.Template
 	AddFromFilesFuncs(name string, funcMap template.FuncMap, files ...string) *template.Template