修改了create api，增加了插入blockchain_project_clients表的操作

app/services/blockchain_project_clients_service.rb

@@ -0,0 +1,17 @@
+class BlockchainProjectClientsService
+
+  # 创建blockchain_project_clients表的一条记录
+  def create_item(project, user, params)
+    status = -1
+    bpc = BlockchainProjectClient.new
+    bpc.project_id = project.id
+    bpc.user_id = user.id
+    bpc.node_id = params[:node_id]
+    if bpc.save
+      status = 0
+      return status, bpc
+    end
+    return status, nil
+  end
+
+end