Rudra 1.0.3

Rudra

Rudra is a .NET Runtime Expression Builder library that allows developers to create queries at runtime that are not predefined or statically known at compile time.

Features

• Dynamic Expression Building: Create expressions at runtime from human-readable string or list of nodes, enabling flexible and powerful querying capabilities.

• Dynamic Type Handling: Supports dynamic type checking and allows for implicit and explicit casting of field datatypes. This feature ensures that any comparable types can be processed without hard-coded type logic.

• Integration with LINQ: The generated expressions can be easily integrated with LINQ queries to filter collections dynamically.

Supported Operations

Unary Operations

Binary Operations

Arithmetic Operations

Relational Operations

Logical Operations

Installation

Rudra is designed for ASP.NET Core and it targets net6.0, net7.0 and net8.0.

Install Rudra package using Nuget Package Manager:

Install-Package Rudra

Or via .NET CLI:

dotnet add package Rudra

Usage and Examples

Suppose you have an object definition for Student :

public enum Gender
{
    Other = 0,
    Male = 1,
    Female = 2
}

public class Student
{
    public int StudentID { get; set; }
    public string? Name { get; set; }
    public DateTime? DateOfBirth { get; set; }
    public Gender Gender { get; set; }
    public DateTime? EnrollmentDate { get; set; }
    public bool IsActive { get; set; }
    public decimal? GPA { get; set; }
    public decimal? TuitionBalance { get; set; }
    public DateTime? GraduationDate { get; set; }
    public bool IsInternational { get; set; }
    public decimal StandardGPA { get; set; }
    public int CreditsEarned { get; set; }
}

Query Definition

Query can be defined in two ways:

• Either as a single string
• As a list of constituent parts (field, operator, and value).

string query = "gender = Female";
List<string> nodes = new() { "Gender", "=", "female" }; 

N.B. Fields are Case Insensitive

Runtime Expression Builder

To create a runtime expression easily, you can use the static class ExpressionBuilder. Call the BuildFilterExpression method and pass the Student object as the generic type parameter.

BuildFilterExpression method accepts both sring and List<string> and returns LINQ Expression.

using Rudra;

// Creating Filter Expression from single string type (query)
var filterExp_query = ExpressionBuilder.BuildFilterExpression<Student>(query);

// Creating Filter Expression from list of constituent parts (nodes)
var filterExp_nodes = ExpressionBuilder.BuildFilterExpression<Student>(nodes);

Getting Results

Use the filterExp returned by BuildFilterExpression .

/// In memory List
List<Student> students;
var result = students.AsQueryable().Where(filterExp).ToList();

/// SQL Server
// Using Entity Framework
public class RudraContext : DbContext
{
    public DbSet<Student> Students { get; set; }
    public RudraContext()
    {
    }
    protected override void OnConfiguring(DbContextOptionsBuilder options)
    {
        options.UseSqlServer(@"ConnectionString");
    }

}
// Now use Context
using (var db = new RudraContext())
{
    var result = db.Students.Where(filterExp).ToList();
} 

Dynamic Query Examples

// Compare decimal? with int fields, it will cast int dynamically to decimal? to work on all scenarios
// CreditsEarned - int field
// TuitionBalance - decimal? field
string query = "CreditsEarned > TuitionBalance";

// Logical AND (Students who are international or have a GPA percentage less than 60%)
string query = "IsInternational = true OR GPA * 10 < 60";

// Logical OR (Students who are active and have a GPA percentage greater than 85%)
string query = "IsActive = true AND GPA * 10 > 85";

// Arithmatic (like checking 20% of tuition balance is more than 500)
string query = "TuitionBalance * (20/100) > 500";

// Compare fields
string query = "GraduationDate <= EnrollmentDate";

// negative value
string query = "TuitionBalance < -100";

// Boolean Type
string query = "IsActive = true";

// For DateTime type use single quote ('')
string query = "GraduationDate > '2021-05-01'";

License

Copyright (c) 2024 Abhishek Bakshi

Rudra is licensed under the MIT License. See the LICENSE file for details.