Add SaveStateWithETag() convenience function (dapr#321)

In the state API there's an existing DeleteStateWithETag() convenience
function but there does not appear to be an equivalent
SaveStateWithETag(). This commit adds SetStateWithETag() so that
consumers of the SDK don't have to employ the more verbose
SaveBulkState() when they only need to update a singular item.

Client code updating a single item with an etag prior to this commit
looks like:

--
item := &dapr.SetStateItem{
	Etag: &dapr.ETag{
		Value: "deadbeef",
	},
	Key:   "order_1",
	Value: []byte(data),
}

err := client.SaveBulkState(ctx, store, item)
--

Client code after this commit can reduce to:

--
err := client.SaveStateWithEtag(ctx, store, "order_1", []byte(data), "deadbeef")
--

Signed-off-by: Mike Brown <[email protected]>

Signed-off-by: Mike Brown <[email protected]>

client/client.go

@@ -90,6 +90,9 @@ type Client interface {
 	// SaveState saves the raw data into store using default state options.
 	SaveState(ctx context.Context, storeName, key string, data []byte, meta map[string]string, so ...StateOption) error
 
+	// SaveState saves the raw data into store using provided state options and etag.
+	SaveStateWithETag(ctx context.Context, storeName, key string, data []byte, etag string, meta map[string]string, so ...StateOption) error
+
 	// SaveBulkState saves multiple state item to store with specified options.
 	SaveBulkState(ctx context.Context, storeName string, items ...*SetStateItem) error
 

client/state.go

@@ -276,6 +276,11 @@ func (c *GRPCClient) ExecuteStateTransaction(ctx context.Context, storeName stri
 
 // SaveState saves the raw data into store, default options: strong, last-write.
 func (c *GRPCClient) SaveState(ctx context.Context, storeName, key string, data []byte, meta map[string]string, so ...StateOption) error {
+	return c.SaveStateWithETag(ctx, storeName, key, data, "", meta, so...)
+}
+
+// SaveStateWithETag saves the raw data into store using provided state options and etag.
+func (c *GRPCClient) SaveStateWithETag(ctx context.Context, storeName, key string, data []byte, etag string, meta map[string]string, so ...StateOption) error {
 	stateOptions := new(StateOptions)
 	for _, o := range so {
 		o(stateOptions)
@@ -289,6 +294,9 @@ func (c *GRPCClient) SaveState(ctx context.Context, storeName, key string, data
 		Metadata: meta,
 		Options:  stateOptions,
 	}
+	if etag != "" {
+		item.Etag = &ETag{Value: etag}
+	}
 	return c.SaveBulkState(ctx, storeName, item)
 }
 

client/state_test.go

@@ -86,14 +86,7 @@ func TestSaveState(t *testing.T) {
 	})
 
 	t.Run("save data with version", func(t *testing.T) {
-		item := &SetStateItem{
-			Etag: &ETag{
-				Value: "1",
-			},
-			Key:   key,
-			Value: []byte(data),
-		}
-		err := testClient.SaveBulkState(ctx, store, item)
+		err := testClient.SaveStateWithETag(ctx, store, key, []byte(data), "1", nil)
 		assert.Nil(t, err)
 	})
 
@@ -147,15 +140,8 @@ func TestDeleteState(t *testing.T) {
 	})
 
 	t.Run("save data again with etag, meta", func(t *testing.T) {
-		err := testClient.SaveBulkState(ctx, store, &SetStateItem{
-			Key:   key,
-			Value: []byte(data),
-			Etag: &ETag{
-				Value: "1",
-			},
-			Metadata: map[string]string{"meta1": "value1"},
-			Options:  &StateOptions{Concurrency: StateConcurrencyFirstWrite, Consistency: StateConsistencyEventual},
-		})
+		meta := map[string]string{"meta1": "value1"}
+		err := testClient.SaveStateWithETag(ctx, store, key, []byte(data), "1", meta, WithConsistency(StateConsistencyEventual), WithConcurrency(StateConcurrencyFirstWrite))
 		assert.Nil(t, err)
 	})
 	t.Run("confirm data saved", func(t *testing.T) {