Fix index loading empty array (#173)

This PR fixes the case when a user tries to load an empty array using
`index.load([], ...)`. Currently, this borks and throws an exception for
something that should have been captured in one of our tests.

Test conditions added, and big fixed.

Author: tylerhutcherson

redisvl/index/storage.py

@@ -210,27 +210,28 @@ def write(
         keys_iterator = iter(keys) if keys else None
         added_keys: List[str] = []
 
-        with redis_client.pipeline(transaction=False) as pipe:
-            for i, obj in enumerate(objects, start=1):
-                # Construct key, validate, and write
-                key = (
-                    next(keys_iterator)
-                    if keys_iterator
-                    else self._create_key(obj, id_field)
-                )
-                obj = self._preprocess(obj, preprocess)
-                self._validate(obj)
-                self._set(pipe, key, obj)
-                # Set TTL if provided
-                if ttl:
-                    pipe.expire(key, ttl)
-                # Execute mini batch
-                if i % batch_size == 0:
+        if objects:
+            with redis_client.pipeline(transaction=False) as pipe:
+                for i, obj in enumerate(objects, start=1):
+                    # Construct key, validate, and write
+                    key = (
+                        next(keys_iterator)
+                        if keys_iterator
+                        else self._create_key(obj, id_field)
+                    )
+                    obj = self._preprocess(obj, preprocess)
+                    self._validate(obj)
+                    self._set(pipe, key, obj)
+                    # Set TTL if provided
+                    if ttl:
+                        pipe.expire(key, ttl)
+                    # Execute mini batch
+                    if i % batch_size == 0:
+                        pipe.execute()
+                    added_keys.append(key)
+                # Clean up batches if needed
+                if i % batch_size != 0:
                     pipe.execute()
-                added_keys.append(key)
-            # Clean up batches if needed
-            if i % batch_size != 0:
-                pipe.execute()
 
         return added_keys
 

tests/unit/test_async_search_index.py

@@ -129,6 +129,13 @@ async def bad_preprocess(record):
         await async_index.load(data, id_field="id", preprocess=bad_preprocess)
 
 
+@pytest.mark.asyncio
+async def test_search_index_load_empty(async_client, async_index):
+    async_index.set_client(async_client)
+    await async_index.create(overwrite=True, drop=True)
+    await async_index.load([])
+
+
 @pytest.mark.asyncio
 async def test_no_id_field(async_client, async_index):
     async_index.set_client(async_client)

tests/unit/test_search_index.py

@@ -125,6 +125,12 @@ def bad_preprocess(record):
         index.load(data, id_field="id", preprocess=bad_preprocess)
 
 
+def test_search_index_load_empty(client, index):
+    index.set_client(client)
+    index.create(overwrite=True, drop=True)
+    index.load([])
+
+
 def test_no_id_field(client, index):
     index.set_client(client)
     index.create(overwrite=True, drop=True)