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[英]ADO.Net retrieving autoincrement values for MS Access database in strongly typed DataSets
[英]Handcrafted Strongly Typed ADO.net DataTable - Can it be cleaner?
我最近遇到了一個非常簡單的Typed DataTable(不使用.XSD)(我丟失了作者的URL,所以我無法相信他),但看起來好像有很多重復的代碼(例如Add / Remove / GetNewRow方法)。
我試圖將重復方法推入超類,但是由於Employee需要通用,所以我遇到了問題。 我希望讓StackOverflow的集體蜂巢思想提出一些想法來解決此問題? (如果有可能的話?)
using System;
using System.Data;
using System.Collections;
using System.Data.SqlClient;
namespace TypedDataSet {
public class Employees : DataTable {
protected SqlDataAdapter _adapter;
public Employees() {
string connectionString = TypedDataSet.Properties.Settings.Default.ConnectionString;
_adapter = new System.Data.SqlClient.SqlDataAdapter("SELECT Id, Firstname, Surname FROM Employee", connectionString);
_adapter.Fill(this);
}
public Employee this[int index] {
get { return (Employee)Rows[index]; }
}
public void Add(Employee row) {
Rows.Add(row);
}
public void Remove(Employee row) {
Rows.Remove(row);
}
public Employee GetNewRow() {
Employee row = (Employee)NewRow();
return row;
}
protected override DataRow NewRowFromBuilder(DataRowBuilder builder) {
return new Employee(builder);
}
public IEnumerator GetEnumerator() {
return Rows.GetEnumerator();
}
protected override Type GetRowType() {
return typeof(Employee);
}
}
public class Employee : DataRow {
internal Employee(DataRowBuilder builder)
: base(builder) {
}
public Int64 Id {
get { return (Int64)base["Id"]; }
set { base["Id"] = value; }
}
public string FirstName {
get { return (string)base["Firstname"]; }
set { base["Firstname"] = value; }
}
public string Surname {
get { return (string)base["Surname"]; }
set { base["Surname"] = value; }
}
}
}
我相信我已經回答了我的問題。 我不得不使用.net 4.0來獲得我希望特別針對動態類型的結果。
因此,更改問題中的現有類:
Employee.cs
using System;
using System.Data;
using System.Collections;
using System.Data.Common;
namespace TypedDataSet {
public class Employees : BaseModel<Employee> {
public Employees(bool loadAll) {
DbDataAdapter adapter = base.Adapter("SELECT * FROM Employees");
adapter.Fill(this);
}
protected override DataRow NewRowFromBuilder(DataRowBuilder builder) {
return new Employee(builder);
}
}
public class Employee : DataRow {
internal Employee(DataRowBuilder builder)
: base(builder) {
}
public Int64 Id {
get { return (Int64)base["Id"]; }
set { base["Id"] = value; }
}
public string FirstName {
get { return (string)base["Firstname"]; }
set { base["Firstname"] = value; }
}
public string Surname {
get { return (string)base["Surname"]; }
set { base["Surname"] = value; }
}
}
}
現在介紹上述類繼承的BaseModel
BaseModel.cs
using System;
using System.Data;
using System.Collections;
using System.Data.Common;
using System.Data.SqlClient;
namespace TypedDataSet {
public class BaseModel<T> : DataTable {
protected DbDataAdapter _adapter;
protected string _connectionString = TypedDataSet.Properties.Settings.Default.ConnectionString;
public BaseModel() {
}
protected DbDataAdapter Adapter(string sql) {
_adapter = new System.Data.SqlClient.SqlDataAdapter(sql, _connectionString);
SqlCommandBuilder cb = new SqlCommandBuilder((SqlDataAdapter)_adapter);
return _adapter;
}
public dynamic this[int index] {
get { return Rows[index]; }
}
public void Add(dynamic row) {
Rows.Add(row);
}
public void Remove(dynamic row) {
Rows.Remove(row);
}
public void Save() {
_adapter.Update(this);
this.AcceptChanges();
}
public dynamic GetNewRow() {
dynamic row = (dynamic)NewRow();
return row;
}
public IEnumerator GetEnumerator() {
return Rows.GetEnumerator();
}
protected override Type GetRowType() {
return typeof(T);
}
}
}
這使我可以使用以下代碼使用該類:
Employees employees = new Employees(true);
Employee employee = employees.GetNewRow();
employee.FirstName = "Greg";
employee.Surname = "Focker";
employees.Add(employee);
employees.Save();
foreach (Employee e in employees) {
Console.WriteLine(e.FirstName + ' ' + e.Surname);
}
我希望進一步增加超時時間,因此如果您對這個小項目感興趣,將來的StackOverflow用戶可以在http://bitbucket.org/Mozketo/typeddataset/中查看,我希望在其中托管代碼。
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