enhance: add example for null and default_value (#2479)

Signed-off-by: lixinguo <[email protected]>
Co-authored-by: lixinguo <[email protected]>

examples/orm/nullable_and_default_value.py

@@ -0,0 +1,114 @@
+# 1. connect to Milvus
+# 2. create collection
+# 3. insert data
+# 4. create index
+# 5. query on entities
+# 6. drop collection
+import time
+
+import numpy as np
+from pymilvus import (
+    connections,
+    utility,
+    FieldSchema, CollectionSchema, DataType,
+    Collection,
+)
+
+fmt = "\n=== {:30} ===\n"
+search_latency_fmt = "search latency = {:.4f}s"
+dim = 8
+
+#################################################################################
+# 1. connect to Milvus
+print(fmt.format("start connecting to Milvus"))
+connections.connect("default", host="localhost", port="19530")
+
+has = utility.has_collection("hello_milvus")
+print(f"Does collection hello_milvus exist in Milvus: {has}")
+
+#################################################################################
+# 2. create collection
+# We're going to create a collection with 4 fields.
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+# | |     field name      | field type |   other attributes  |                  field description               |
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+# |1|         "pk"        |   VarChar  |    is_primary=True  |                "primary field"                   |
+# | |                     |            |     auto_id=False   |                                                  |
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+# |2|    "nullable_fid"   |    Double  |    nullable=True    |        "a double field can insert null"          |
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+# |3| "default_value_fid" |    Int64   |   default_value=1   |  "a int64 field can insert with default value"   |
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+# |4|     "embeddings"    | FloatVector|        dim=8        |              "float vector with dim 8"           |
+# +-+---------------------+------------+---------------------+--------------------------------------------------+
+fields = [
+    FieldSchema(name="pk", dtype=DataType.VARCHAR, is_primary=True, auto_id=False, max_length=100),
+    FieldSchema(name="nullable_fid", dtype=DataType.DOUBLE,nullable=True),
+    FieldSchema(name="default_value_fid", dtype=DataType.INT64,default_value=1),
+    FieldSchema(name="embeddings", dtype=DataType.FLOAT_VECTOR, dim=dim)
+]
+
+schema = CollectionSchema(fields, "hello_milvus is the demo to introduce the nullable and default value functions")
+
+print(fmt.format("Create collection `hello_milvus`"))
+hello_milvus = Collection("hello_milvus", schema, consistency_level="Strong")
+
+################################################################################
+# 3. insert data
+# For fields marked as nullable=True: 
+# you can skip the field when inserting data, or set it directly to a null value, and the system will treat it as null 
+# For fields marked default_value: 
+# the system will automatically apply this value if no data is specified for the field during insertion
+
+print(fmt.format("Start inserting entities"))
+rng = np.random.default_rng(seed=19530)
+
+data_rows = [
+    {
+        # skip the field when inserting data
+        "pk": "19530",
+        "embeddings": rng.random((1, dim), np.float32)[0]
+    },
+    {
+        # set it directly to a null value
+        "pk": "19531",
+        "nullable_fid": None,
+        "default_value_fid": None,
+        "embeddings": rng.random((1, dim), np.float32)[0]
+    },
+]
+
+hello_milvus.insert(data_rows)
+
+hello_milvus.flush()
+print(f"Number of entities in Milvus: {hello_milvus.num_entities}")  # check the num_entities
+
+################################################################################
+# 4. create index
+print(fmt.format("Start Creating index IVF_FLAT"))
+index = {
+    "index_type": "IVF_FLAT",
+    "metric_type": "L2",
+    "params": {"nlist": 128},
+}
+
+hello_milvus.create_index("embeddings", index)
+
+################################################################################
+# 5. query on entities
+print(fmt.format("Start loading"))
+hello_milvus.load()
+
+print(fmt.format("Start querying"))
+start_time = time.time()
+result = hello_milvus.query(expr='pk in ["19530","19531"]', output_fields=["nullable_fid", "default_value_fid","embeddings"])
+end_time = time.time()
+
+print(f"query result:\n-{result[0]}")
+print(search_latency_fmt.format(end_time - start_time))
+
+###############################################################################
+# 6. drop collection
+# Finally, drop the hello_milvus collection
+print(fmt.format("Drop collection `hello_milvus`"))
+utility.drop_collection("hello_milvus")