Elegance C#

Q: I need to filter a generic list with a dynamic query:

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List<string> l;
var x = l.Where(*dynamic query*)

How would i do this using LINQ?
but it appears to not work with objects that use IEnumerable(generic lists included).
Can anyone offer any ideas?

Answers

Assuming you mean a string-based query: the dynamic LINQ library will work fine; just call .AsQueryable() first:

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string s = *dynamic query*
var qry = l.AsQueryable().

Introduction

Some programming tasks require dynamic nature of properties exposed by an object. E.g. it might be needed to access object property by a given key, it might be needed to get all object properties and iterate over them. Dynamic properties are useful when you need to manage them at runtime, when your object is already instantiated.

In this article we are going to create simple implementation of dynamic properties using C# programming language. We’ll use generics for our dynamic properties to make the implementation more flexible and to avoid boxing operations when value types are used for underlying property values.

• Assembly:T1.dll
• Namespace:T1.Common

Using the code

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MyClass c1 = new MyClass();
c1.Name = "123";
int i = c1.ID;

Using .NET Invoke Method

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MyClass c1 = new MyClass();
PropertyInfo pi = c1.GetProperty("Name");
pi.SetValue(c1, "123");
pi = c1.GetProperty("ID");
int i = (int)pi.GetValue(c1, null);

Using DynamicProperty Method

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MyClass c1 = new MyClass();
var setName = DynamicProperty.SetProperty("Name");
setName(c1, "123");
var getID = DynamicProperty.GetProperty("ID");
int i = getID(c1);

DynamicProperty Method is fast than Invoke Method.

Introduction

If you want to clone the same object of class, you must inherit “ICloneable” interface and implement Clone() method for clone function. Now only through ValueHelper Class can be simple to complete this goal.

• Assembly:T1.dll
• Namespace:T1.Common

Using the code:

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MyClass a = new MyClass();
a.Id = 123;
a.Name = "abc";
MyClass b = new MyClass();
b.Id = a.Id;
b.Name = a.Name;
Console.WriteLine("b Id={0} Name={1}", b.Id, b.Name);

And the following code in the same

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MyClass a = new MyClass();
a.Id = 123;
a.Name = "abc";
MyClass b = new MyClass();
ValueHelper.CopyData(a, b);
Console.WriteLine("b Id={0} Name={1}", b.Id, b.Name);

You can also use Property.GetValue/SetValue to achieve the same purpose, but ValueHelper.CopyData performance on faster than the Property.GetValue/SetValue.

ValueHelper Class copy only int/float/string… basic types of variables, do not copy the object type variable.

Therefore, the following code to try to copy the a.Item object will be skipped.

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class MyClass1
{
	public string ID{get; set;}
}

class MyClass2
{
	public string Name{get; set;}
	public MyClass1 Item{get; set;}
}

MyClass2 a = new MyClass2();
a.Name = "abc";
a.Item = new MyClass1();
a.ID = "123";
MyClass2 b = new MyClass2();
ValueHelper.CopyData(a, b);
//b.Item will be null.

Introduction

Each database connection parameters set different. DataConfig so you can easily set these parameters.

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Assembly:T1.Data.dll
Namespace:T1.Data

DataConfig Properties:

• ProviderType ProviderType
• string Server
• string Database
• string LoginId
• string Password

Through the above property setting, you can easily export a variety of different database connection string.
Using the code:

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DataConfig cfg = new DataConfig();
cfg.ProviderType = ProviderType.SqlServer;
cfg.Server = "172.0.0.1";
cfg.Database = "Northwind";
cfg.LoginId = "sa";
cfg.Password = "123";
console.WriteLine(cfg.ConnectString);

If you wish change to Oracle…

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cfg.ProviderType = ProviderType.Oracle;
console.WriteLine(cfg.ConnectString);

Even if you wish change to SqlExpress…

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cfg.ProviderType = ProviderType.SqlExpress;
console.WriteLine(cfg.ConnectString);

In addition you can also simplify the traditional connection string in app.Config file.

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<add name="db1" connectionString="Data Source=172.0.0.1;Network Library=DBMSSOCN;Initial Catalog=Northwind;User ID=sa;Password=123"></add>

Change to…

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<add name="db1" connectionString="ProviderType=SqlServer;Server=172.0.0.1;Database=Northwind;User ID=sa;Password=123"></add>

If you wish change to Oracle connection string…

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<add name="db1" connectionString="ProviderType=Oracle;Server=172.0.0.1;Database=Northwind;User ID=sa;Password=123"></add>

With DataConfig, you do not have to remember some special database connection parameters.