How to get item from backend after clicking on the url

Question

I build a simple store website. Currently, I have built a home page where I have a list of products, after clicking on a specific product, it takes us to the page of that product and displays its details.Everything works fine because on the homepage I am transferring the data of that particular product to its detail page by state. Its looks like:

<Link
  to={"/" + item.categoryModel.cateGoryName + "/" + item.product_id}  
  state={{ product_details: item }}
>
  <Info>
    <Title>{item.shortName}</Title>
    <Desc>{item.shortDesc}</Desc>
    <Price>{item.newPrice},00zł</Price>       
  </Info>
</Link>

Also I build url for specific product.

For example:

• HomePage: "/"
• Categories: "/computers"
• Product: "/computers/1"

But when I type "/computers/1" without navigating to a specific product through the home page, state of course is Null. Can anyone tell me how to get a specific product from the backend without using state. I use for frontend Reactjs and Springboot for backend.