C# Mongodb 操作：嵌套、数组 等示例

1,一个字段是数组，如果数组中不存在这个记录时，向数组增加一个记录。

            FilterDefinitionBuilder<WorkflowDo> fd = Builders<WorkflowDo>.Filter;
            var f = fd.And(fd.Eq(x => x.Id, record.Id), fd.Not(fd.ElemMatch(x => x.Definition, x => x.Version == newVersionStr)));

            UpdateDefinitionBuilder<WorkflowDo> up = Builders<WorkflowDo>.Update;
            var p = up.Push(x => x.Definition, definition);
            var result = await collection.UpdateOneAsync(f, p);

首先是区配条件，找到这个根记录、数组中是否已经存在这个记录。

            var f = fd.And(fd.Eq(x => x.Id, record.Id), fd.Not(fd.ElemMatch(x => x.Definition, x => x.Version == newVersionStr)));

然后通过 Push ，向数组推送一个记录。

up.Push(x => x.Definition, definition);

这样，并不需要提前查询数据库一次。

条件更新：

        public async Task<ServiceResult> SetStateAsync(ObjectId id, WorkflowInstanceStatus state)
        {
            var f = Builders<WorkflowInstanceDo>.Filter.Where(x => x.Id == id);
            UpdateDefinitionBuilder<WorkflowInstanceDo> up = Builders<WorkflowInstanceDo>.Update;

            var p = up.Set(x => x.Status, state);
            var collection = _mongodb.GetCollection<WorkflowInstanceDo>();

            var result = await collection.UpdateOneAsync(f, p);
            return R.UpdateSuccess();
        }