由于MongoDB.Driver中的Find方法也支持表达式写法，结合【通用查询设计思想】这篇文章中的查询思想，个人基于MongoDB扩展了一些常用的方法。
首先我们从常用的查询开始，由于MongoDB.Driver支持类似于AutoMapper返回的指定属性（Project<TDto>方法），所以这里都是基于泛型的扩展
查询
/// <summary>
/// 同步查询指定条件的数据，并且返回指定类型TDto
/// </summary>
/// <typeparam name="TEntity">查询实体</typeparam>
/// <typeparam name="TDto">返回类型</typeparam>
/// <param name="source"></param>
/// <param name="query"></param>
public static IFindFluent<TEntity, TDto> FindSync<TEntity, TDto>(this IMongoCollection<TEntity> source, IQuery<TEntity> query)
where TEntity : class
{
var projection = GetTDtoReturnProperties<TEntity, TDto>(); var expression = query?.GenerateExpression();
if (null == expression)
{
var emptyExpression = Builders<TEntity>.Filter.Empty;
return source.Find(emptyExpression).Project<TDto>(projection);
} return source.Find(expression).Project<TDto>(projection);
} /// <summary>
/// 获取指定的返回列
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <typeparam name="TDto"></typeparam>
/// <returns></returns>
private static ProjectionDefinition<TEntity, TDto> GetTDtoReturnProperties<TEntity, TDto>()
where TEntity : class
{
var returnType = typeof(TDto); var fieldList = new List<ProjectionDefinition<TEntity>>();
foreach (var property in returnType.GetProperties())
{
fieldList.Add(Builders<TEntity>.Projection.Include(property.Name));
} return Builders<TEntity>.Projection.Combine(fieldList);
}
这里主要是利用了IQuery接口中的GenerateExpression方法，如果前端传来了查询参数，则拼装返回我们的表达式，如果没有，默认返回一个空的Filter，再通过Project<TDto>映射关系到TDto上。
排序
/// <summary>
/// 排序方法
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <typeparam name="TDto"></typeparam>
/// <param name="source"></param>
/// <param name="sortInfo"></param>
/// <returns></returns>
public static IFindFluent<TEntity, TDto> Sort<TEntity, TDto>(this IFindFluent<TEntity, TDto> source, ISortInfo sortInfo)
where TEntity : class
{
var sort = Builders<TEntity>.Sort;
SortDefinition<TEntity> sortDefinition = null;
if (sortInfo != null)
{
if (!string.IsNullOrWhiteSpace(sortInfo.Order) && !string.IsNullOrWhiteSpace(sortInfo.Field))
{
if (sortInfo.Order.Contains("asc"))
sortDefinition = sort.Ascending(sortInfo.Field);
if (sortInfo.Order.Contains("desc"))
sortDefinition = sort.Descending(sortInfo.Field);
}
} return source.Sort(sortDefinition);
}
这里前端是使用了LayUI的表格，所以API中的参数是Order和Field，我们也可以结合例如JQuery的DataTable或者其他框架的表格，只是参数SortInfo稍微不一样，大家结合实际情况来更改业务即可。
分页
/// <summary>
/// 查询指定条件的数据
/// </summary>
/// <typeparam name="TEntity">查询的实体</typeparam>
/// <typeparam name="TDto">返回的类型</typeparam>
/// <param name="source"></param>
/// <param name="query">查询条件</param>
/// <param name="page">分页信息</param>
public static async Task<PageResult<TDto>> ToPageResultAsync<TEntity, TDto>(this IMongoCollection<TEntity> source, IQuery<TEntity> query, IPageInfo page)
where TEntity : class
{
var pageIndex = Math.Max(, page.PageIndex);
var pageSize = Math.Max(, page.PageSize); var cursor = source.FindSync<TEntity, TDto>(query); var pageResult = new PageResult<TDto>
{
PageIndex = pageIndex,
PageSize = pageSize,
TotalCount = (int)await cursor.CountDocumentsAsync(),
Data = await cursor.Skip(pageSize * (pageIndex - )).Limit(pageSize).Sort(page).ToListAsync()
}; return pageResult;
}
增和删暂时不写了，官方API也提供了批处理的接口，都可以直接用的。
来看一下我们这几个扩展方法的应用（基于aspnet core）
public class MongoHelper
{
private static readonly string DbName = ConfigHelper.GetSetting("MongoDb").ToString();
private static readonly string ConnStr = ConfigHelper.GetSetting("MongoDbConnStr").ToString();
private static IMongoDatabase Db { get; } private static readonly object LockHelper = new object(); #region cotr static MongoHelper()
{
if (Db == null)
{
lock (LockHelper)
{
if (Db == null)
{
var client = new MongoClient(ConnStr);
Db = client.GetDatabase(DbName);
}
}
}
} #endregion #region query /// <summary>
/// 查询一个集合中的所有数据 其集合的名称为T的名称
/// </summary>
/// <typeparam name="TEntity">该集合数据的所属类型</typeparam>
/// <typeparam name="TDto">返回类型</typeparam>
/// <returns>返回一个Result<TDto />
/// </returns>
public static async Task<Result<TDto>> QueryAsync<TEntity, TDto>(IQuery<TEntity> query, string collectionName = "")
where TEntity : class
{
//检查是否存在该文档
var existed = await CollectionExists(Db, string.IsNullOrWhiteSpace(collectionName) ? DbName : collectionName);
if (existed)
{
var collection = Db.GetCollection<TEntity>(string.IsNullOrWhiteSpace(collectionName) ? DbName : collectionName);
var result = collection.FindSync<TEntity, TDto>(query);
var listResult = await result.ToListAsync();
return Result.FromData(listResult.FirstOrDefault());
}
else
{
return Result.FromCode<TDto>(ResultCode.NoSuchCollection);
}
} /// <summary>
/// 查询一个集合中的所有数据 其集合的名称为T的名称
/// </summary>
/// <typeparam name="TEntity">该集合数据的所属类型</typeparam>
/// <typeparam name="TDto">返回数据类型</typeparam>
/// <returns>返回一个List列表</returns>
public static async Task<Result<List<TDto>>> QueryListAsync<TEntity, TDto>(IQuery<TEntity> query, string collectionName = "")
where TEntity : class
{
var collection = Db.GetCollection<TEntity>(string.IsNullOrWhiteSpace(collectionName) ? DbName : collectionName);
var result = collection.FindSync<TEntity, TDto>(query);
var listResult = await result.ToListAsync();
return Result.FromData(listResult);
} /// <summary>
/// 分页方法
/// </summary>
/// <typeparam name="TEntity"></typeparam>
/// <typeparam name="TDto"></typeparam>
/// <param name="collectionName">指定文档名称</param>
/// <param name="query"></param>
/// <returns></returns>
public static async Task<PageResult<TDto>> QueryPageResultAsync<TEntity, TDto>(PageQuery<TEntity> query, string collectionName = "")
where TEntity : class
{
//检查是否存在该文档
var existed = await CollectionExists(Db, string.IsNullOrWhiteSpace(collectionName) ? DbName : collectionName);
if (existed)
{
var collection = Db.GetCollection<TEntity>(string.IsNullOrWhiteSpace(collectionName) ? DbName : collectionName);
return await collection.ToPageResultAsync<TEntity, TDto>(query, query);
}
else
{
return new PageResult<TDto>
{
Code = ResultCode.NoSuchCollection
};
}
} #endregion #region Private Methods /// <summary>
/// 检查是否存在该文档
/// </summary>
/// <param name="database">指定的数据库</param>
/// <param name="collectionName">文档名称</param>
/// <returns></returns>
private static async Task<bool> CollectionExists(IMongoDatabase database, string collectionName)
{
var options = new ListCollectionsOptions
{
Filter = Builders<BsonDocument>.Filter.Eq("name", collectionName)
}; return await database.ListCollections(options).AnyAsync();
}
#endregion
}
有了这个帮助类，我们可以看一下应用层的具体应用
/// <summary>
/// TEntity的分页查询
/// </summary>
/// <typeparam name="TEntity">查询实体</typeparam>
/// <typeparam name="TDto">返回结果</typeparam>
/// <param name="query">查询条件</param>
/// <returns></returns>
public async Task<PageResult<TDto>> GetPagedLogsAsync<TEntity, TDto>(PageQuery<TEntity> query)
where TEntity : class
{
return await MongoHelper.QueryPageResultAsync<TEntity, TDto>(query, typeof(TEntity).Name);
} /// <summary>
/// TEntity的查询
/// </summary>
/// <typeparam name="TEntity">查询实体</typeparam>
/// <typeparam name="TDto">返回结果</typeparam>
/// <param name="query">查询条件</param>
/// <returns></returns>
public async Task<Result<TDto>> GetSpecifyLogAsync<TEntity, TDto>(IQuery<TEntity> query)
where TEntity : class
{
return await MongoHelper.QueryAsync<TEntity, TDto>(query, typeof(TEntity).Name);
}
看一下我们Controller的调用
/// <summary>
/// 获取指定条件的日志分页列表
/// </summary>
/// <param name="query">查询参数</param>
/// <returns></returns>
[HttpPost]
public async Task<PageResult<LogResult>> SearchPagedLogsAsync(LogPageQuery query)
{
return await _logBll.GetPagedLogsAsync<Log, LogResult>(query);
} /// <summary>
/// 获取指定条件的日志
/// </summary>
/// <param name="id">查询参数</param>
/// <returns></returns>
public async Task<Result<LogResult>> GetLogByIdAsync(string id)
{
if (string.IsNullOrWhiteSpace(id))
return Result.FromCode<LogResult>(ResultCode.Fail);
return await _logBll.GetSpecifyLogAsync<Log, LogResult>(new Query<Log>(m => m.Id == new ObjectId(id)));
}
我这里的例子是为了符合单一职责的设计原则，所以指定了GetLogByIdAsync这样的单一接口，如果大家喜欢单个方法满足更多功能，可以参照【通用查询设计思想】文章中的Controller写法。
让我知道你们有更好的想法！