BLToolKit：它是否支持 IQueryable？答案

【问题标题】：BLToolKit: Does it support IQueryable?BLToolKit：它是否支持 IQueryable？
【发布时间】：2011-01-05 20:45:57
【问题描述】：

通常使用 BLToolKit 我通过以下方式从数据库中获取数据：

using ( DbManager db = new MyDbManager() )
{
    IList<MyObjects> objects = db
        .SetCommand(query)//sometimes with additional parameters
        .ExecuteList<MyObjects>()
        ;
}

我希望有能力做到以下几点：

using ( DbManager db = new MyDbManager() )
{
    IQueryable<MyObjects> qObjs = db
        .SetCommand(query)//sometimes with additional parameters
        .ExecuteQuery<MyObjects>()// here I don't want query actually to be executed
        ;

    // ... another logic, that could pass qObj into other part of program

    IList<MyObjects> objects = qObjs
        .Where(obj=>obj.SomeValue>=SomeLimit)    // here I want to put additional filters
        .ExecuteList()  // and only after that I wan't to execute query and fetch results
        ;
}

可以通过修改原始查询字符串（修改 WHERE 部分）来解决此问题，但有时会非常复杂。

有什么简单的方法吗？

谢谢。欢迎任何想法！

【问题讨论】：

标签： c# .net .net-4.0 iqueryable bltoolkit

【解决方案1】：

using ( DbManager db = new MyDbManager() )
{
    IQueryable<MyObjects> qObjs = 
        from p in db.GetTable<MyObjects>()
        //sometimes with additional parameters
        select p;

    // ... another logic, that could pass qObj into other part of program

    IList<MyObjects> objects = qObjs
        .Where(obj=>obj.SomeValue>=SomeLimit)    // here I want to put additional filters
        .ToList()  // and only after that I wan't to execute query and fetch results
        ;
}

【讨论】：

【解决方案2】：

如果你想拥有 IQueriable ，你必须使用 Linq。 BlToolkit.Linq 和 BlToolkit.Data.Linq 必须导入。

        IQueryable<DataModel.Object> query  = db.Object;


        If ((int)cmb_somthing.SelectedValue) > 0 {

            int ID  = (int)cmb_somthing.SelectedValue;
            query = query.Where(m=> m.ID = ID);

        }
        query = query.Where(m=> m.Date >= StartDate &&
                                m.Date <= EndDate);

【讨论】：