优化commit第一次提交，parent为空而不是“”

src/models/commit.rs

@@ -2,7 +2,7 @@ use std::time::SystemTime;
 
 use serde::{Deserialize, Serialize};
 
-use crate::store;
+use crate::{store, utils::util};
 
 use super::{index::Index, object::Hash, tree::Tree};
 /*Commit
@@ -26,6 +26,9 @@ impl Commit {
     pub fn get_hash(&self) -> String {
         self.hash.clone()
     }
+    pub fn get_date(&self) -> String {
+        util::format_time(&self.date)
+    }
     pub fn get_tree_hash(&self) -> String {
         self.tree.clone()
     }

src/models/tree.rs

@@ -91,7 +91,7 @@ impl Tree {
             .map(|file| util::to_workdir_relative_path(file))
             .collect();
 
-        store_path_to_tree(&file_entries, "".to_string().into())
+        store_path_to_tree(&file_entries, "".into())
     }
 
     pub fn load(hash: &String) -> Tree {