ExpressionFun.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;

public class Program
{
    public static void Main()
    {
        var model = new Customer { Id = 1 };

        var result = DataService.Exists<Customer, int>(c => model.Id);

        Console.WriteLine(result);
    }
}

public class Customer
{
    public int Id { get; set; }
}

public class DataService
{
    public static bool Exists<TEntity, TProperty>(Expression<Func<TEntity, TProperty>> expression)
        where TEntity : class
    {
        TProperty value = expression.Compile().Invoke(null);

        var propertyInfo = ((MemberExpression)expression.Body).Member;

        var parameter = Expression.Parameter(typeof(TEntity), "entity");
        var property = Expression.Property(parameter, propertyInfo.Name);
        var body = Expression.Equal(property, Expression.Constant(value));

        var lambda = Expression.Lambda<Func<TEntity, bool>>(body, parameter);

        using (var context = new DbContext())
        {
            return context.Set<TEntity>().Any(lambda);
        }
    }
}

public class DbContext : IDisposable
{
    public IQueryable<T> Set<T>()
    {
        return new List<T>().AsQueryable();
    }

    public void Dispose()
    {
    }
}