Add has to Path and Map

contracts/cw1155-base/src/contract.rs

@@ -233,9 +233,9 @@ pub fn execute_mint(
     }
 
     // insert if not exist
-    let key = TOKENS.key(&token_id);
-    if deps.storage.get(&key).is_none() {
-        key.save(deps.storage, &"".to_owned())?;
+    if !TOKENS.has(deps.storage, &token_id) {
+        // we must save some valid data here
+        TOKENS.save(deps.storage, &token_id, &String::new())?;
     }
 
     Ok(rsp)
@@ -329,10 +329,9 @@ pub fn execute_batch_mint(
         event.add_attributes(&mut rsp);
 
         // insert if not exist
-        let key = TOKENS.key(&token_id);
-        if deps.storage.get(&key).is_none() {
-            // insert an empty entry so token enumeration can find it
-            key.save(deps.storage, &"".to_owned())?;
+        if !TOKENS.has(deps.storage, &token_id) {
+            // we must save some valid data here
+            TOKENS.save(deps.storage, &token_id, &String::new())?;
         }
     }
 

packages/storage-plus/src/map.rs

@@ -66,6 +66,12 @@ where
         self.key(k).may_load(store)
     }
 
+    /// has returns true or false if any data is at this key, without parsing or interpreting the
+    /// contents.
+    pub fn has(&self, store: &dyn Storage, k: K) -> bool {
+        self.key(k).has(store)
+    }
+
     /// Loads the data, perform the specified action, and store the result
     /// in the database. This is shorthand for some common sequences, which may be useful.
     ///
@@ -199,6 +205,33 @@ mod test {
         assert_eq!(None, john.may_load(&store).unwrap());
     }
 
+    #[test]
+    fn existence() {
+        let mut store = MockStorage::new();
+
+        // set data in proper format
+        let data = Data {
+            name: "John".to_string(),
+            age: 32,
+        };
+        PEOPLE.save(&mut store, b"john", &data).unwrap();
+
+        // set and remove it
+        PEOPLE.save(&mut store, b"removed", &data).unwrap();
+        PEOPLE.remove(&mut store, b"removed");
+
+        // invalid, but non-empty data
+        store.set(&PEOPLE.key(b"random"), b"random-data");
+
+        // any data, including invalid or empty is returned as "has"
+        assert!(PEOPLE.has(&store, b"john"));
+        assert!(PEOPLE.has(&store, b"random"));
+
+        // if nothing was written, it is false
+        assert!(!PEOPLE.has(&store, b"never-writen"));
+        assert!(!PEOPLE.has(&store, b"removed"));
+    }
+
     #[test]
     fn composite_keys() {
         let mut store = MockStorage::new();

packages/storage-plus/src/path.rs

@@ -65,6 +65,12 @@ where
         may_deserialize(&value)
     }
 
+    /// has returns true or false if any data is at this key, without parsing or interpreting the
+    /// contents. It will returns true for an length-0 byte array (Some(b"")), if you somehow manage to set that.
+    pub fn has(&self, store: &dyn Storage) -> bool {
+        store.get(&self.storage_key).is_some()
+    }
+
     /// Loads the data, perform the specified action, and store the result
     /// in the database. This is shorthand for some common sequences, which may be useful.
     ///