Fix CosmosDB state store handling of nulls (dapr#1974)

Signed-off-by: Bernd Verst <4535280+berndverst@users.noreply.github.com>

state/azure/cosmosdb/cosmosdb.go

@@ -249,7 +249,18 @@ func (c *StateStore) Get(req *state.GetRequest) (*state.GetResponse, error) {
 	}
 
 	if items[0].IsBinary {
-		bytes, _ := base64.StdEncoding.DecodeString(items[0].Value.(string))
+		if items[0].Value == nil {
+			return &state.GetResponse{
+				Data: make([]byte, 0),
+				ETag: ptr.String(items[0].Etag),
+			}, nil
+		}
+
+		bytes, decodeErr := base64.StdEncoding.DecodeString(items[0].Value.(string))
+		if decodeErr != nil {
+			c.logger.Warnf("CosmosDB state store Get request could not decode binary string: %v. Returning raw string instead.", decodeErr)
+			bytes = []byte(items[0].Value.(string))
+		}
 
 		return &state.GetResponse{
 			Data: bytes,
@@ -583,6 +594,9 @@ func (c *StateStore) findCollection() (*documentdb.Collection, error) {
 
 func createUpsertItem(contentType string, req state.SetRequest, partitionKey string) (CosmosItem, error) {
 	byteArray, isBinary := req.Value.([]uint8)
+	if len(byteArray) == 0 {
+		isBinary = false
+	}
 
 	ttl, err := parseTTL(req.Metadata)
 	if err != nil {

state/azure/cosmosdb/cosmosdb_test.go

@@ -182,6 +182,97 @@ func TestCreateCosmosItem(t *testing.T) {
 
 		assert.Equal(t, "AQ==", m)
 	})
+
+	t.Run("create item with null data", func(t *testing.T) {
+		// Bytes are handled the same way, does not matter if is JSON or JPEG.
+		bytes, err := json.Marshal(nil)
+		assert.NoError(t, err)
+
+		req := state.SetRequest{
+			Key:   "testKey",
+			Value: bytes,
+		}
+
+		item, err := createUpsertItem("application/json", req, partitionKey)
+		assert.NoError(t, err)
+		assert.Equal(t, partitionKey, item.PartitionKey)
+		assert.Equal(t, "testKey", item.ID)
+		assert.False(t, item.IsBinary)
+		assert.Nil(t, item.TTL)
+
+		// items need to be marshallable to JSON with encoding/json
+		b, err := json.Marshal(item)
+		assert.NoError(t, err)
+
+		j := map[string]interface{}{}
+		err = json.Unmarshal(b, &j)
+		assert.NoError(t, err)
+
+		assert.Nil(t, j["value"])
+	})
+
+	t.Run("create item with empty string data and JSON content type", func(t *testing.T) {
+		// Bytes are handled the same way, does not matter if is JSON or JPEG.
+		bytes := []byte("")
+
+		req := state.SetRequest{
+			Key:   "testKey",
+			Value: bytes,
+		}
+
+		item, err := createUpsertItem("application/json", req, partitionKey)
+		assert.NoError(t, err)
+		assert.Equal(t, partitionKey, item.PartitionKey)
+		assert.Equal(t, "testKey", item.ID)
+		assert.False(t, item.IsBinary)
+		assert.Nil(t, item.TTL)
+
+		// items need to be marshallable to JSON with encoding/json
+		b, err := json.Marshal(item)
+		assert.NoError(t, err)
+
+		j := map[string]interface{}{}
+		err = json.Unmarshal(b, &j)
+		assert.NoError(t, err)
+
+		m, ok := (j["value"].(string))
+
+		assert.Truef(t, ok, "value should be a string")
+		assert.NotContains(t, j, "ttl")
+		assert.Equal(t, "", m)
+	})
+
+	t.Run("create item with empty string data and string content type", func(t *testing.T) {
+		// Bytes are handled the same way, does not matter if is JSON or JPEG.
+		bytes := []byte("")
+
+		req := state.SetRequest{
+			Key:   "testKey",
+			Value: bytes,
+		}
+
+		item, err := createUpsertItem("text/plain", req, partitionKey)
+		assert.NoError(t, err)
+		assert.Equal(t, partitionKey, item.PartitionKey)
+		assert.Equal(t, "testKey", item.ID)
+		assert.False(t, item.IsBinary)
+		assert.Nil(t, item.TTL)
+
+		// items need to be marshallable to JSON with encoding/json
+		b, err := json.Marshal(item)
+		assert.NoError(t, err)
+
+		j := map[string]interface{}{}
+		err = json.Unmarshal(b, &j)
+		assert.NoError(t, err)
+
+		m, ok := (j["value"].(string))
+
+		assert.Truef(t, ok, "value should be a string")
+		assert.NotContains(t, j, "ttl")
+
+		assert.Equal(t, "", m)
+	})
 }
 
 func TestCreateCosmosItemWithTTL(t *testing.T) {