c# - LINQ:动态 Where 子句切换大小写组合

Question

我有一个绑定(bind)到 angridview 的列表，我希望能够“即时”创建过滤器 Where 子句， 而过滤器选项的组合由用户控制。

按模型 bool 属性过滤原始列表并允许切换每个过滤条件的最佳方法是什么？

我知道 filterdList 不是必需的，但我已经看到的所有其他解决方案都不允许切换 Where 子句的条件。

public partial class Form1 : Form
{
    List<dummy> Origlist = new List<dummy> {
        new dummy { pk = 1 ,  istype1 = true,  istype2  = false, istype3=false, istype4=false },
        new dummy { pk = 2 ,  istype1 = true,  istype2 = false,  istype3=false, istype4=false },
        new dummy { pk = 3 ,  istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 4 ,  istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 5 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 6 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 7 ,  istype1 = false, istype2 = false,  istype3=false, istype4=true },
        new dummy { pk = 8 ,  istype1 = false, istype2 = false,  istype3=false, istype4=true },
        new dummy { pk = 9 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 10 , istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 11 , istype1 = false, istype2 = false,  istype3=false, istype4=false }
        };
    List<dummy> filteredList = new List<dummy>(); 
    public Form1()
    {
        InitializeComponent();
    }

    private void Bind()
    {
        dataGridView1.DataSource = null;
        dataGridView1.DataSource = filteredList;
    }


    private void checkBox1_CheckedChanged(object sender, EventArgs e)
    {
        if (checkBox1.Checked)
        {
            filteredList.AddRange(Origlist.Where(a => a.istype1 == true).ToList());
        }
        else
        {
            filteredList.RemoveAll(a => a.istype1 == true);
        }
        Bind();
    }



    private void checkBox2_CheckedChanged(object sender, EventArgs e)
    {
        if (checkBox2.Checked)
        {
            filteredList.AddRange(Origlist.Where(a => a.istype2 == true).ToList());
        }
        else
        {
            filteredList.RemoveAll(a => a.istype2 == true);
        }
        Bind();
    }

    private void checkBox3_CheckedChanged(object sender, EventArgs e)
    {
        if (checkBox3.Checked)
        {
            filteredList.AddRange(Origlist.Where(a => a.istype3 == true).ToList());
        }
        else
        {
            filteredList.RemoveAll(a => a.istype3 == true);
        }
        Bind();
    }

    private void checkBox4_CheckedChanged(object sender, EventArgs e)
    {
        if (checkBox4.Checked)
        {
            filteredList.AddRange(Origlist.Where(a => a.istype4 == true).ToList());
        }
        else
        {
            filteredList.RemoveAll(a => a.istype4 == true);
        }
        Bind();
    }

}

Answer 1

尝试这样的事情(未经测试):

public partial class Form1 : Form
{
    List<dummy> Origlist = new List<dummy> {
        new dummy { pk = 1 ,  istype1 = true,  istype2  = false, istype3=false, istype4=false },
        new dummy { pk = 2 ,  istype1 = true,  istype2 = false,  istype3=false, istype4=false },
        new dummy { pk = 3 ,  istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 4 ,  istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 5 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 6 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 7 ,  istype1 = false, istype2 = false,  istype3=false, istype4=true },
        new dummy { pk = 8 ,  istype1 = false, istype2 = false,  istype3=false, istype4=true },
        new dummy { pk = 9 ,  istype1 = false, istype2 = false,  istype3=true,  istype4=false },
        new dummy { pk = 10 , istype1 = false, istype2 = true,   istype3=false, istype4=false },
        new dummy { pk = 11 , istype1 = false, istype2 = false,  istype3=false, istype4=false }
    };

    Options options = new Options();

    private class Options {
        public bool istype1 { get; set; }
        public bool istype2 { get; set; }
        public bool istype3 { get; set; }
        public bool istype4 { get; set; }
    }

    public Form1()
    {
        InitializeComponent();
    }

    private void Bind()
    {
        dataGridView1.DataSource = null;
        dataGridView1.DataSource = OrigList.Where(a =>
          (options.istype1 && a.istype1) ||
          (options.istype2 && a.istype2) ||
          (options.istype3 && a.istype3) ||
          (options.istype4 && a.istype4)
        ).ToList();
    }


    private void checkBox1_CheckedChanged(object sender, EventArgs e)
    {
        options.istype1 = checkBox1.checked;
        Bind();
    }



    private void checkBox2_CheckedChanged(object sender, EventArgs e)
    {
        options.istype2 = checkBox2.checked;
        Bind();
    }

    private void checkBox3_CheckedChanged(object sender, EventArgs e)
    {
        options.istype3 = checkBox3.checked;
        Bind();
    }

    private void checkBox4_CheckedChanged(object sender, EventArgs e)
    {
        options.istype4 = checkBox4.checked;
        Bind();
    }

}

还有其他方法可以减少重复，但这只是一个开始。