LINQ“where”带参数

Question

我相信这是菜鸟的错误，但我自己找不到答案。

public class Database : DataContext 
{ 
    public Table<Record> RecordTable; 
    public Database(string connection) : base(connection) {} 
} 

[Table(Name = "RecordsTable")] 
public class Record 
{ 
    [Column(IsPrimaryKey = true, CanBeNull = false)] 
    public int codedID; 
} 

// inside some class 
private void ReadTestData(Database openedDatabase, int expectedValue) 
{ 
    Table<Record> rec = openedDatabase.GetTable<Record>(); 
    var q = 
     from a in rec 
     where (GetMonth == expectedValue) // <--- that line doesn't work 
     select a; 

    foreach (var b in q) { System.Console.WriteLine("something"); } 
} 

static Expression<Func<Record, int>> GetMonth = a => a.codedID/10000; 

public static int DecodeMonth(int codedID) 
{ 
    int month = codedID/10000; 
    //(...) 
    return month; 
} 

我想打电话DecodeMonth功能和比较它与expectedValue返回值。我应该怎么做？

我做了一些研究和管理，以这样的运行代码：

var q = openedDatabase.RecordTable.Where(GetMonthBool); 

static Expression<Func<Record, bool>> GetMonthBool = a => (a.codedID/10000 == 1); 

但expectedValue被硬编码为“1” - 这并没有解决我的问题。

Answer 1

创建，创建这样的表达

private Expression<Func<Record, bool>> GetMonthBoolFunc(int value) 
{ 
    return a => (a.codedID/10000 == value); 
} 

var q = openedDatabase.RecordTable.Where(GetMonthBoolFunc(1));