怎样优雅地增删查改（五）：按组织架构查询-526互联

原理
实现
应用
测试

之前我们实现了Employee，Alarm管理模块以及通用查询应用层。

Employee的集合查询业务，是通过重写CreateFilteredQueryAsync方法，来实现按组织架构查询的过滤条件。

我们将这段逻辑代码提取到通用查询应用层中，便可实现在任何业务的按组织架构查询。

原理

EmployeeAppService中，CreateFilteredQueryAsync方法组织架构的过滤条件代码如下：

var organizationUnitUsers = await organizationUnitAppService.GetOrganizationUnitUsersAsync(new GetOrganizationUnitUsersInput()
{
    Id = input.OrganizationUnitId.Value
});
if (organizationUnitUsers.Count() > 0)
{
    var ids = organizationUnitUsers.Select(c => c.Id);
    query = query.Where(t => ids.Contains(t.Id));
}
else
{
    query = query.Where(c => false);
}

CreateFilteredQueryAsync是通过业务用户的IRepository获取实体的IQueryable 然后通过query.Where()实现了按组织架构的过滤条件。

IQueryable是一泛型类接口，泛型参数是实体类。要想在任意实体实现Where的过滤条件，我们使用动态拼接语言集成查询 (LINQ) 的方式实现通用查询接口，有关LINQ表达式，请阅读 LINQ 教程和有关 Lambda 表达式的文章。

实现

定义按组织架构查询过滤器（IOrganizationOrientedFilter）接口，查询实体列表Dto若实现该接口，将筛选指定 OrganizationUnitId 下的用户关联的实体。

public interface IOrganizationOrientedFilter
{
    Guid? OrganizationUnitId { get; set; }
}

重写CreateFilteredQueryAsync方法，代码如下


protected override async Task<IQueryable<TEntity>> CreateFilteredQueryAsync(TGetListInput input)
{
    var query = await ReadOnlyRepository.GetQueryableAsync();

    query = await ApplyOrganizationOrientedFiltered(query,input);

    return query;
}

对于OrganizationUnit服务，其依赖关系在应用层，查找指定组织架构的用户将在CurdAppServiceBase的子类实现。创建一个抽象方法GetUserIdsByOrganizationAsync

protected abstract Task<IEnumerable<Guid>> GetUserIdsByOrganizationAsync(Guid organizationUnitId)

创建应用过滤条件方法：ApplyOrganizationOrientedFiltered，在此实现拼接LINQ表达式，代码如下：

protected virtual async Task<IQueryable<TEntity>> ApplyOrganizationOrientedFiltered(IQueryable<TEntity> query, TGetListInput input)
{
    if (input is IOrganizationOrientedFilter && HasProperty<TEntity>("UserId"))
    {
        var property = typeof(TEntity).GetProperty("UserId");
        var filteredInput = input as IOrganizationOrientedFilter;
        if (filteredInput != null && filteredInput.OrganizationUnitId.HasValue)
        {

            var ids = await GetUserIdsByOrganizationAsync(filteredInput.OrganizationUnitId.Value);
            Expression originalExpression = null;
            var parameter = Expression.Parameter(typeof(TEntity), "p");
            foreach (var id in ids)
            {
                var keyConstantExpression = Expression.Constant(id, typeof(Guid));
                var propertyAccess = Expression.MakeMemberAccess(parameter, property);
                var expressionSegment = Expression.Equal(propertyAccess, keyConstantExpression);

                if (originalExpression == null)
                {
                    originalExpression = expressionSegment;
                }
                else
                {
                    originalExpression = Expression.Or(originalExpression, expressionSegment);
                }
            }

            var equalExpression = originalExpression != null ?
                    Expression.Lambda<Func<TEntity, bool>>(originalExpression, parameter)
                    : p => false;

            query = query.Where(equalExpression);

        }

    }
    return query;
}

请注意，可应用过滤的条件为：

input需实现IOrganizationOrientedFilter接口
实体必须包含UserId字段

否则将原封不动返回IQueryable对象。

应用

在上一章Alarm管理模块中，我们已经写好了AlarmAppService，我们需要为其实现GetUserIdsByOrganizationAsync方法。改造AlarmAppService代码如下：

public class AlarmAppService : ExtendedCurdAppServiceBase<Matoapp.Health.Alarm.Alarm, AlarmDto, AlarmDto, AlarmBriefDto, long, GetAllAlarmInput, GetAllAlarmInput, CreateAlarmInput, UpdateAlarmInput>, IAlarmAppService
{
    private readonly IOrganizationUnitAppService organizationUnitAppService;

    public AlarmAppService(
        IOrganizationUnitAppService organizationUnitAppService,
        IRepository<Matoapp.Health.Alarm.Alarm, long> basicInventoryRepository) : base(basicInventoryRepository)
    {
        this.organizationUnitAppService = organizationUnitAppService;
    }

    protected override async Task<IEnumerable<Guid>> GetUserIdsByOrganizationAsync(Guid organizationUnitId)
    {
        var organizationUnitUsers = await organizationUnitAppService.GetOrganizationUnitUsersAsync(new GetOrganizationUnitUsersInput()
        {
            Id = organizationUnitId
        });

        var ids = organizationUnitUsers.Select(c => c.Id);
        return ids;
    }
}