Fetching data from the database based on different categories - sql

Question

I am setting up the query that fetch data from 3 tables based on filters that user select. filters can be multiple or can be none.
I made stored procedures with different combination. But I know that was the worst thing that I did.
var result = (from product in context.Products
from img in context.ProductImage
from saved in context.SavedProduct
where (cat.Color.Contains(product.Color)
& cat.BrandName.Contains(product.Brand_Name)
& cat.Fabric.Contains(product.Fabric)
& cat.Design.Contains(product.Design))
select new
{
product.ProductID,
product.Price,
product.Brand_Name,
product.Title,
product.Color,
product.Fabric,
product.Design,
img.Image,
saved.ProductSavedCounter,
}).ToList();
Product related details in a Product Table. Product images in a ProductImage table. And How many people saved this product are in SavedProduct table.
It returns the products only if user select all filters means when user select red color, Nike brand, cotton fabric etc. If one is missed than this query returns nothing. I want when 1 or 2 are missed than it should return data according to other selected fitters.
Pardon me if there is any mistake I am new bee.
And I missed the joins.

Answer 1

This may help:-
Note: I assumed the ProductID is in the other tables to make the joins, in general if your model have navigation properties for the Product image and save product you would not need the joins.
var result = from product in context.Products
join img in context.ProductImage on product.ProductID equals img.ProductID
join saved in context.SavedProduct on product.ProductID equals saved.ProductID
where (
(string.IsNullOrEmpty(cat.Color) || cat.Color.Equals(product.Color))
& (string.IsNullOrEmpty(cat.BrandName) || cat.Brand_Name.Equals(product.Brand_Name))
& (string.IsNullOrEmpty(cat.Fabric) || cat.Fabric.Equals(product.Fabric))
& (string.IsNullOrEmpty(cat.Design) || cat.Design.Equals(product.Design))
& (
((string.IsNullOrEmpty(cat.Color) ? 1 : 0) +
(string.IsNullOrEmpty(cat.BrandName) ? 1 : 0) +
(string.IsNullOrEmpty(cat.Fabric) ? 1 : 0) +
(string.IsNullOrEmpty(cat.Design) ? 1 : 0)) >= 2) //at least two conditions
)
select new {
product.ProductID,
product.Price,
product.Brand_Name,
product.Title,
product.Color,
product.Fabric,
product.Design,
img.Image,
saved.ProductSavedCounter,
};
I think a better solution would to build it gradually, as below:-
//build the joins
var result = (from product in context.Products
join img in context.ProductImage on product.ProductID equals img.ProductID
join saved in context.SavedProduct on product.ProductID equals saved.ProductID
select new { product, img, saved }).AsQueryable();
//get number of conditions avaliable
var conditionCount = (string.IsNullOrEmpty(cat.Color) ? 1 : 0) +
(string.IsNullOrEmpty(cat.Brand_Name) ? 1 : 0) +
(string.IsNullOrEmpty(cat.Fabric) ? 1 : 0) +
(string.IsNullOrEmpty(cat.Design) ? 1 : 0);
if (conditionCount >= 2)
{
//add the condition if they exists
if (!string.IsNullOrEmpty(cat.Color))
result = result.Where(x => cat.Color.Equals(x.product.Color));
if (!string.IsNullOrEmpty(cat.Brand_Name))
result = result.Where(x => cat.Brand_Name.Equals(x.product.Brand_Name));
if (!string.IsNullOrEmpty(cat.Fabric))
result = result.Where(x => cat.Fabric.Equals(x.product.Fabric));
if (!string.IsNullOrEmpty(cat.Design))
result = result.Where(x => cat.Design.Equals(x.product.Design));
//make the final select
var finalResult = result.Select(x => new
{
x.product.ProductID,
x.product.Price,
x.product.Brand_Name,
x.product.Title,
x.product.Color,
x.product.Fabric,
x.product.Design,
x.img.Image,
x.saved.ProductSavedCounter,
}).ToList();
}
And if you meant that whenever any filter is missing the query should ignore it remove the condition count and the if statement for it.