Get value of metadata field value from search result output (#213)

[+] Add entity function to Hit object
[+] Add usage in the example
[+] Add changes to CHANGELOG

Signed-off-by: Leonardo1412 <leonardo1412@andesvr.com>

Co-authored-by: Leonardo1412 <leonardo1412@andesvr.com>

CHANGELOG.md

@@ -1,6 +1,7 @@
 # pymilvus 0.0.1(TBD)
 
 ## Task
+- Get value of metadata fields from search result output (#90)
 - Improve interface documentation (#89)
 - Add examples in partition.py (#88)
 - add example for index.py (#87)

examples/hello_milvus.py

@@ -25,7 +25,8 @@ def hello_milvus():
     dim = 128
     default_fields = [
         schema.FieldSchema(name="count", dtype=DataType.INT64, is_primary=True),
-        schema.FieldSchema(name="score", dtype=DataType.DOUBLE),
+        # Change field schema name to distinguish search result score
+        schema.FieldSchema(name="random_value", dtype=DataType.DOUBLE),
         schema.FieldSchema(name="float_vector", dtype=DataType.FLOAT_VECTOR, dim=dim)
     ]
     default_schema = schema.CollectionSchema(fields=default_fields, description="test collection")
@@ -40,7 +41,13 @@ def hello_milvus():
     import random
     nb = 3000
     vectors = [[random.random() for _ in range(dim)] for _ in range(nb)]
-    collection.insert([[i for i in range(nb)], [float(i) for i in range(nb)], vectors])
+    collection.insert(
+        [
+            [i for i in range(nb)],
+            [float(random.randrange(-20,-10)) for _ in range(nb)],
+            vectors
+        ]
+    )
 
     print(f"\nGet collection entities...")
     print(collection.num_entities)
@@ -58,13 +65,18 @@ def hello_milvus():
     import time
     start_time = time.time()
     print(f"\nSearch...")
-    res = collection.search(vectors[-2:], "float_vector", search_params, topK, "count > 100")
+    # define output_fields of search result
+    res = collection.search(
+        vectors[-2:], "float_vector", search_params, topK,
+        "count > 100", output_fields=["count", "random_value"]
+    )
     end_time = time.time()
 
     # show result
     for hits in res:
         for hit in hits:
-            print(hit)
+            # Get value of the random value field for search result
+            print(hit, hit.entity.get("random_value"))
     print("search latency = %.4fs" % (end_time - start_time))
 
     # drop collection

pymilvus_orm/search.py

@@ -11,6 +11,7 @@
 # the License.
 
 import abc
+from pymilvus.client.abstract import Entity
 
 
 class _IterableWrapper:
@@ -99,6 +100,16 @@ def id(self) -> int:
         """
         return self._hit.id
 
+    @property
+    def entity(self) -> Entity:
+        """
+        Return the Entity of the hit record.
+
+        :return pymilvus Entity object:
+            The entity content of the hit record.
+        """
+        return self._hit.entity
+
     @property
     def distance(self) -> float:
         """