What is the best pattern to use LINQ to C#

public class CommonService { private readonly DataContext _context; public CommonRepository() { _context = new DataContext(); } public CommonRepository(DataContext context) { _context = context; } public List GetAll() { var query = from m in _context.MyModel select m; return m.ToList(); } } or p

什么是使用LINQ to C#的最佳模式

public class CommonService { private readonly DataContext _context; public CommonRepository() { _context = new DataContext(); } public CommonRepository(DataContext context) { _context = context; } public List GetAll() { var query = from m in _context.MyModel select m; return m.ToList(); } } 要么

Dynamic + linq compilation error

I'll say up front that I am doing some really scary things with linq on dynamic data. But I can't figure out why this query fails to compile: Error 1 The property '<>h__TransparentIdentifier0' cannot be used with type arguments public class Program { public static void Main(string[] args) { var docs = new dynamic[0]; var q = from doc in docs

动态+ linq编译错误

我会先说,我正在用动态数据进行一些非常可怕的事情。 但我不明白为什么这个查询无法编译: 错误1属性'<> h__TransparentIdentifier0'不能与类型参数一起使用 public class Program { public static void Main(string[] args) { var docs = new dynamic[0]; var q = from doc in docs where doc["@metadata"]["Raven-Entity-Name"] == "Cases" where

Is it better to yield return lookup lists or preload a static list in c#?

I have a simple lookup list that I will use to populate a dropdown in Silverlight. In this example I'm using US States. I'm trying to figure out if its better to return a static list or use the yield keyword. Of the following two pieces of code, which is the preferred and why? Version 1: Using yield return public class States { public static IEnumerable<string> GetNames()

在c#中生成返回查找列表或预加载静态列表会更好吗?

我有一个简单的查找列表,我将用它来填充Silverlight中的下拉列表。 在这个例子中,我使用美国国家。 我试图找出它是否更好地返回静态列表或使用yield关键字。 以下两段代码中,哪些是首选的,为什么? 版本1:使用收益率回报 public class States { public static IEnumerable<string> GetNames() { yield return "Alabama"; yield return "Alaska"; yield return "Arizona";

Nested yield return with IEnumerable

I have the following function to get validation errors for a card. My question relates to dealing with GetErrors. Both methods have the same return type IEnumerable<ErrorInfo> . private static IEnumerable<ErrorInfo> GetErrors(Card card) { var errors = GetMoreErrors(card); foreach (var e in errors) yield return e; // further yield returns for more validation err

带IEnumerable的嵌套收益率回报

我有以下功能来获取卡的验证错误。 我的问题涉及处理GetErrors。 两种方法都有相同的返回类型IEnumerable<ErrorInfo> 。 private static IEnumerable<ErrorInfo> GetErrors(Card card) { var errors = GetMoreErrors(card); foreach (var e in errors) yield return e; // further yield returns for more validation errors } 是否有可能返回GetMoreErrors所有错误,而不必通过它们枚举?

Convert DataTable to IEnumerable<T>

I am trying to convert a DataTable to an IEnumerable. Where T is a custom type I created. I know I can do it by creating a List but I was think there was a slicker way to do it using IEnumerable. Here is what I have now. private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable) { var tankReadings = new List<TankReading>(); foreach (DataRow

将DataTable转换为IEnumerable <T>

我正试图将DataTable转换为IEnumerable。 其中T是我创建的自定义类型。 我知道我可以通过创建一个List来做到这一点,但我认为有一种使用IEnumerable的方法。 这是我现在拥有的。 private IEnumerable<TankReading> ConvertToTankReadings(DataTable dataTable) { var tankReadings = new List<TankReading>(); foreach (DataRow row in dataTable.Rows) { var tankR

I am wondering about the state of connection and impact on code performance by 'yield' while iterating over data reader object

Here is my sample code that I am using to fetch data from database: on DAO layer: public IEnumerable<IDataRecord> GetDATA(ICommonSearchCriteriaDto commonSearchCriteriaDto) { using(DbContext) { DbDataReader reader = DbContext.GetReader("ABC_PACKAGE.GET_DATA", oracleParams.ToArray(), CommandType.StoredProcedure); while (reader.Read()) { yield retur

我在迭代数据读取器对象时想知道“yield”的连接状态和对代码性能的影响

以下是我用于从数据库获取数据的示例代码:在DAO层上: public IEnumerable<IDataRecord> GetDATA(ICommonSearchCriteriaDto commonSearchCriteriaDto) { using(DbContext) { DbDataReader reader = DbContext.GetReader("ABC_PACKAGE.GET_DATA", oracleParams.ToArray(), CommandType.StoredProcedure); while (reader.Read()) { yield return reader; } } }

Linq to combine (or) join two datatables into one

I'm having problem in getting correct data from two datatables into one by using Linq in C#. My datatables' data are coming from Excel file reading (not from DB). I have tried below linq but return rows count is not what I want (my goal is to retrieve all data but for verification, I'm checking on row count so that I can know is it correct or not easily). In dt1, I have 2645 rec

Linq将(或)将两个数据表合并为一个

我在通过在C#中使用Linq将两个数据表中的正确数据合并为一个数据库时遇到了问题。 我的数据表的数据来自Excel文件读取(而不是数据库)。 我已经尝试了下面的LINQ,但返回行数并不是我想要的(我的目标是检索所有数据,但为了验证,我正在检查行数,以便我可以知道它是正确的还是不容易)。 在dt1中,我有2645条记录。 在dt2中,我有2600条记录。 返回行数是2600(看起来它正在做正确的连接逻辑)。 var v1 = from d1

Multiple on clause from DataTable to DataTable via LINQ

I have a question about LINQ There are two DataTables I wanna to inner join, the code as follows: DataTable dt1 = new DataTable(); DataTable dt2 = new DataTable(); dt1.Columns.Add("TEST1"); dt1.Columns.Add("TEST2"); dt1.Columns.Add("TEST3"); dt1.Columns.Add("TEST4"); dt2.Columns.Add("TEST2"); dt2.Columns.Add("TEST5"); dt2.Columns.Add("TEST6"); dt2.Column

通过LINQ从DataTable到DataTable的多个子句

我有一个关于LINQ的问题有两个我想要内连接的DataTables,代码如下: DataTable dt1 = new DataTable(); DataTable dt2 = new DataTable(); dt1.Columns.Add("TEST1"); dt1.Columns.Add("TEST2"); dt1.Columns.Add("TEST3"); dt1.Columns.Add("TEST4"); dt2.Columns.Add("TEST2"); dt2.Columns.Add("TEST5"); dt2.Columns.Add("TEST6"); dt2.Columns.Add("TEST7"); for (int i =

Full outer join, on 2 data tables, with a list of columns

I have 2 data tables, which I do not know their list of data columns. This list must be extracted at run time, and be used for the full outer join. When using these columns, the columns between the 2 tables need to be merged, and I need all data to be displayed. Till now what I am doing is Get common columns, using intersect, and implementing IEqualityComparer Create a new datatable, wit

在2个数据表上完全外连接,并有一列列

我有2个数据表,我不知道他们的数据列的列表。 该列表必须在运行时提取,并用于完整外连接。 使用这些列时,需要合并两个表格之间的列,并且需要显示所有数据。 直到现在我正在做的是 获取公共列,使用相交,并实现IEqualityComparer 用这些列创建一个新的数据表,以便这两个数据表将被合并到这个新表中 但是,我在第二步中遇到了Linq问题。 直到现在我有: 获取常用列 // Get common columns var comm

Linq to work with slightly complex selectlist

Here is a simplified select list <select name="stuff"> <option value="">All</option> <option>Test</option> <option>Test1</option> <option>Test2</option> <option>Horses</option> </select> Based on the value from the select list, I wish to find related values from my table. LINQ 1. someTable.Where(r =&g

Linq使用稍微复杂的选择列表

这是一个简化的选择列表 <select name="stuff"> <option value="">All</option> <option>Test</option> <option>Test1</option> <option>Test2</option> <option>Horses</option> </select> 根据选择列表中的值,我希望从我的表中找到相关的值。 LINQ 1. someTable.Where(r => r.someField.Contains(stuff)); 2. someTable