feat(region):完成行政区划获取的功能。

controller/region.go

@@ -0,0 +1,38 @@
+package controller
+
+import (
+	"electricity_bill_calc/response"
+	"electricity_bill_calc/service"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+)
+
+type _RegionController struct {
+	Router *gin.Engine
+}
+
+var RegionController *_RegionController
+
+func InitializeRegionController(router *gin.Engine) {
+	RegionController = &_RegionController{
+		Router: router,
+	}
+
+	RegionController.Router.GET("/region/:rid", RegionController.FetchRegions)
+}
+
+func (_RegionController) FetchRegions(c *gin.Context) {
+	result := response.NewResult(c)
+	requestParentId := c.Param("rid")
+	regions, err := service.RegionService.FetchSubRegions(requestParentId)
+	if err != nil {
+		result.Error(http.StatusInternalServerError, err.Error())
+		return
+	}
+	if len(regions) == 0 {
+		result.Json(http.StatusNotFound, "未能获取到相关的行政区划。", gin.H{"regions": make([]string, 0)})
+		return
+	}
+	result.Json(http.StatusOK, "已经获取到相关的行政区划。", gin.H{"regions": regions})
+}