Question

如何在Linq to SQL中循环列名

var foo = (from f in db.bar select f).ToList()

我想要做的是遍历每个列名，即

    foreach bar d in foo
{
    foreach column in d
      {<do something>}
}

这可能吗？

Answer 1

这是一个将LINQ-to-sql查询作为可枚举字典返回的方法：

IEnumerable<IDictionary<string, object>> GetValues<T>(DataContext context,
                                                         IQueryable<T> query)
    where T : class
{
    var propertyInfos = typeof(T).GetProperties().ToDictionary (pi => pi.Name);
    foreach(var entity in context.GetTable<T>())
    {
        yield return (context.Mapping.GetTable(typeof(T)).RowType.DataMembers
           .Where(dm => !dm.IsAssociation).Select (dm => dm.Name)
        .Select(name => new { name, 
                              value = propertyInfos[name].GetValue(entity, null)
                            })
        .ToDictionary (x => x.name, y => y.value));
    }
}

您可以从字典中获取列名称和值：

var foo = (from f in db.bar select f);
foreach(var dictionary in GetValues(db, foo))
{
    // do something with dictionary keys and/or values
}

Answer 2

如果您还没有将映射模型扩展到其他字段，或者也不介意迭代它们，则可以使用：

var fields = typeof(Product).GetFields();
foreach(var item in db.Products)  
{  
    foreach(var f in fields)  
    {  
        Console.WriteLine(f.Name + ": " + f.GetValue(item));
    }  
 }

Answer 3

以下是我认为您想要的一个示例，如果这不足以让您入门，请详细说明您的需求。

var myTable = new DataTable();
myTable.Columns.Add("Column One");
myTable.Columns.Add("Column Two");

var newRow = myTable.NewRow();
newRow[0] = 11111;
newRow[1] = 22222;
myTable.Rows.Add(newRow);

var newRow2 = myTable.NewRow();
newRow2 [0] = 33333;
newRow2 [1] = 44444;
myTable.Rows.Add(newRow2);


foreach (var row in myTable.AsEnumerable())
{
    foreach (DataColumn column in myTable.Columns)
    {
        Console.WriteLine("Column {0}, Row {1}, Value {2}", column.ColumnName, myTable.Rows.IndexOf(row), row[column]);
    }
}

Linq循环遍历C行中的列＃

3 个答案: