Software Development

software development notes, main category for Cs, Java, and other programming experiences.

Query a list of objects by its property

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Reflection;
using System.Linq;
using System.Xml;
using System.Xml.Linq;
class Employee {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Role {
    int _id;
    string role;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public string Role {
        get { return role; }
        set { role = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Employee> people = new List<Employee> {
               new Employee { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Employee { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"}
            };

        List<Role> roles = new List<Role> {
              new Role  { ID = 1, Role = "Manager" },
              new Role  { ID = 2, Role = "Developer" }
            };


        var query = people
                    .Where(p => p.ID == 1)
                    .Select(p => new { p.FirstName, p.LastName });
    }
}

Query by Person's FirstName

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;

class Person {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Person> people = new List<Person> {
               new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"},
               new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"},
               new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"}
            };

        var query = from p in people
                    where p.FirstName == "B"
                    select p;

    }
}

Select object in a List

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;

class Person {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Person> people = new List<Person> {
               new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"},
               new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"},
               new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"}
            };
        var query = from p in people select p;
    }
}

Query an array of object by its property value

Posted on by coder 
   
 
using System;
using System.Collections.Generic;
using System.Linq;
using System.Drawing;
public class Book {
    public String Title { get; set; }

    public override String ToString() {
        return Title;
    }
}

class Program {
    static void Main(string[] args) {
        Book[] books = {
      new Book { Title="A" },
      new Book { Title="F" },
      new Book { Title="E" } };

        var titles =
          books
            .Where(book => book.Title.Contains("A"))
            .Select(book => book.Title);

    }
}

an untidy nested query

Posted on by coder 
   
 

using System;
using System.Collections.Generic;
using System.Linq;
public class MainClass {
    public static void Main() {
        string[] names = { "Tom", "Dick", "Harry", "Mary", "Jay" };

        IEnumerable<string> query =
          Enumerable.Select(
            Enumerable.OrderBy(
              Enumerable.Where(
                names, n => n.Contains("a")
              ), n => n.Length
            ), n => n.ToUpper()
          );
    }
}

Nested query list

Posted on by coder 
   
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Reflection;

class Person {
    int _id;
    int _idRole;
    string _lastName;
    string _firstName;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public int IDRole {
        get { return _idRole; }
        set { _idRole = value; }
    }

    public string LastName {
        get { return _lastName; }
        set { _lastName = value; }
    }

    public string FirstName {
        get { return _firstName; }
        set { _firstName = value; }
    }
}
class Role {
    int _id;
    string role;

    public int ID {
        get { return _id; }
        set { _id = value; }
    }

    public string Role {
        get { return role; }
        set { role = value; }
    }
}
class Program {
    static void Main(string[] args) {
        List<Person> people = new List<Person> {
               new Person { ID = 1, IDRole = 1, LastName = "A", FirstName = "B"},
               new Person { ID = 2, IDRole = 2, LastName = "G", FirstName = "T"},
               new Person { ID = 3, IDRole = 2, LastName = "G", FirstName = "M"},
               new Person { ID = 4, IDRole = 3, LastName = "C", FirstName = "G"}
            };
        List<Role> roles = new List<Role> {
               new Role { ID = 1, Role = "Manager" },
               new Role { ID = 2, Role = "Developer" }
            };
        var query = people
                    .Where(p => p.ID == 1)
                    .SelectMany(p => roles
                                    .Where(r => r.ID == p.ID)
                                    .Select(r => new { p.FirstName, p.LastName, r.Role }));
    }
}

Grouped Min

Posted on by coder

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

public class MainClass {
public static void Main() {

List products = GetProductList();

var categories =
from p in products
group p by p.Category into g
select new { Category = g.Key, TotalUnitsInStock = g.Min(p => p.UnitsInStock) };

Console.Write(categories);
}
static List GetProductList() {
List empTree = new List();
empTree.Add(new Product { ProductName = “A”, Category = “O”, UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “B”, Category = “O”, UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 2 });
empTree.Add(new Product { ProductName = “C”, Category = “O”, UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 3 });
empTree.Add(new Product { ProductName = “D”, Category = “O”, UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 4 });
empTree.Add(new Product { ProductName = “E”, Category = “O”, UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 5 });
empTree.Add(new Product { ProductName = “F”, Category = “O”, UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 6 });
return empTree;
}
static List GetCustomerList() {
List empTree = new List();
empTree.Add(new Product { ProductName = “A”, Category = “O”, UnitPrice = 12, UnitsInStock = 5, Total = 36, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “B”, Category = “O”, UnitPrice = 2, UnitsInStock = 4, Total = 35, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “C”, Category = “O”, UnitPrice = 112, UnitsInStock = 3, Total = 34, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “D”, Category = “O”, UnitPrice = 112, UnitsInStock = 0, Total = 33, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “E”, Category = “O”, UnitPrice = 1112, UnitsInStock = 2, Total = 32, OrderDate = new DateTime(2005, 1, 1), Id = 1 });
empTree.Add(new Product { ProductName = “F”, Category = “O”, UnitPrice = 11112, UnitsInStock = 0, Total = 31, OrderDate = new DateTime(2005, 1, 1), Id = 1 });

List l = new List();
l.Add(new Customer { CompanyName = “A”, Region = “R1”, UnitsInStock = 1, Orders = empTree, CustomerId = 0 });
l.Add(new Customer { CompanyName = “B”, Region = “R2”, UnitsInStock = 2, Orders = empTree, CustomerId = 1 });
l.Add(new Customer { CompanyName = “C”, Region = “R3”, UnitsInStock = 3, Orders = empTree, CustomerId = 2 });
l.Add(new Customer { CompanyName = “D”, Region = “R4”, UnitsInStock = 4, Orders = empTree, CustomerId = 3 });
l.Add(new Customer { CompanyName = “E”, Region = “R5”, UnitsInStock = 5, Orders = empTree, CustomerId = 4 });
return l;
}

}
class Customer : IComparable {
public string CompanyName { get; set; }
public string Region { get; set; }
public List Orders { get; set; }
public int UnitsInStock { get; set; }
public int CustomerId { get; set; }

public override string ToString() {
return String.Format(“Id: {0}, Name: {1}, Region: {3}”, this.CustomerId, this.CompanyName, this.Region);
}
int IComparable.CompareTo(Customer other) {
if (other == null)
return 1;

if (this.CustomerId > other.CustomerId)
return 1;

if (this.CustomerId < other.CustomerId) return -1; return 0; } } class Product : IComparable {
public string ProductName { get; set; }
public string Category { get; set; }
public int UnitPrice { get; set; }
public int UnitsInStock { get; set; }
public int Total { get; set; }
public DateTime OrderDate { get; set; }
public int Id { get; set; }

public override string ToString() {
return String.Format(“Id: {0}, Name: {1} , Category: {3}”, this.Id, this.ProductName, this.Category);
}
int IComparable.CompareTo(Product other) {
if (other == null)
return 1;
if (this.Id > other.Id)
return 1;

if (this.Id < other.Id) return -1; return 0; } } [/csharp]