canerdk/Nuget.DynamicLinqSearch

Expression Helper

Expression helper, translates your written rules into a dynamic query.

Usage

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public decimal Price { get; set; }

    public Product(int id, string name, decimal price)
    {
        Id = id;
        Name = name;
        Price = price;
    }
}

Let's assume you have a product model.

var products = new List<Product>
{
    new Product(1, "Keyboard", 500),
    new Product(2, "Mouse", 700),
    new Product(3, "Ram", 2000),
    new Product(4, "Speaker", 1000),
    new Product(5, "Monitor", 3000)
};

Let's create a filtering model to generate dynamic queries for your product listings.

List<FilterQuery> rules = new List<FilterQuery>()
{
    new FilterQuery()
    {
        Column = "Name",
        Condition = "Keyboard",
        Relation = RuleRelation.Contains,
        Statement = "Or"
    },
    new FilterQuery()
    {
        Column = "Name",
        Condition = "Mouse",
        Relation = RuleRelation.Contains,
        Statement = "Or"
    },
    new FilterQuery()
    {
        Column = "Price",
        Condition = "1000",
        Relation = RuleRelation.LessThan,
        Statement = "And"
    }
};

Let's send this model to our function that generates dynamic queries.

var filter = ExpressionHelper.BuildDynamicFilter<Product>(rules);

The result of the "filter" variable is:

x => x.Name.Contains("Keyboard") || x.Name.Contains("Mouse") && x.Price <= 1000

Summary:

var filter = ExpressionHelper.BuildDynamicFilter<Product>(rules);
var results = queryable.Where(filter).ToList();

Result:

[
    {
	    "id":  1,
	    "name":  "Keyboard",
	    "price":  500
    },
    {
	    "id":  2,
	    "name":  "Mouse",
	    "price":  700
    }
]