Fix importing plugin dashboards (#21501)

#21350 introduced a bug regarding import of plugin dashboards. 
This should fix this and add custom validation if not importing 
plugin dashboard and dashboard property is missing.

Ref #21350

Co-Authored-By: Arve Knudsen <arve.knudsen@gmail.com>

pkg/api/dtos/plugins.go

@@ -56,7 +56,7 @@ type ImportDashboardCommand struct {
 	PluginId  string                         `json:"pluginId"`
 	Path      string                         `json:"path"`
 	Overwrite bool                           `json:"overwrite"`
-	Dashboard *simplejson.Json               `json:"dashboard" binding:"Required"`
+	Dashboard *simplejson.Json               `json:"dashboard"`
 	Inputs    []plugins.ImportDashboardInput `json:"inputs"`
 	FolderId  int64                          `json:"folderId"`
 }

pkg/api/plugins.go

@@ -179,6 +179,10 @@ func GetPluginMarkdown(c *m.ReqContext) Response {
 }
 
 func ImportDashboard(c *m.ReqContext, apiCmd dtos.ImportDashboardCommand) Response {
+	if apiCmd.PluginId == "" && apiCmd.Dashboard == nil {
+		return Error(422, "Dashboard must be set", nil)
+	}
+
 	cmd := plugins.ImportDashboardCommand{
 		OrgId:     c.OrgId,
 		User:      c.SignedInUser,