当querystring为空时，如何计算特定类别？

Question

I have a menu on my masterpage / defaultpage where I'm listing x categories. I would like to make a count of how many products there are in each category.

EX:

Bananas(20)

Apples(8)

Strawberries(5)

So far, I have this:

 var listSubMenu = __account.GetAllProductCategories();
 var sb = new StringBuilder();
    for (int i = 0; i < listSubMenu.Rows.Count; i++)
    {
        var r = listSubMenu.Rows[i];

        var catid = Request.QueryString["thespecific_category_id_but_how_do_i_get_it?"];
        var count = __account.GetSpecificCategory(id);

        sb.AppendFormat(String.Format(@"<li{0}><a href='/account/products.aspx?categoryid={0}'>{1} ({2})</a></li>", r["cat_id"], r["cat_name"], count.Rows.Count));

    }
    active_sub_products.Text = sb.ToString();

My DataTable:
public DataTable GetAllProductCategories()
    {
        const string request =
        @"
            SELECT * FROM products_category
            WHERE cat_active = 1
            ORDER BY cat_name ASC
        ";
        using (var query = new MySqlCommand(request))
        {
            return __dbConnect.GetData(query);
        }
    }

Obiously i need the specific categoryid, but how to I request that without having querystrings running since it is on the default page. Am I missing something obious?

Thanks alot.

Answer 1

You should loop through your categories and get the ID from there. Not from the querystring since that is related to you page (as you wrote yourself as well).

Given your example, I would expect that __account.GetAllProductCategories() would return already the ID's you need

In that case you would use something like

var catid = listSubMenu.id;

But id depends on the type of what your __account returns.

Answer 2

If I'm correct in my guess at your result schema from GetAllProductCategories()...

["cat_id"]["cat_name"]

[1][Apples]

[2][Bananas]

[3][Oranges]

var cat_id = r["cat_id"]

or possibly

var cat_id = Int32.Parse(r["cat_id"])

I would also change:

sb.AppendFormat(String.Format(@"<li{0}><a href='/account/products.aspx?categoryid={0}'>{1} ({2})</a></li>", r["cat_id"], r["cat_name"], count.Rows.Count));

To:

sb.AppendFormat(String.Format(@"<li><a href='/account/products.aspx?categoryid={0}'>{1} ({2})</a></li>", cat_id, r["cat_name"], count.Rows.Count));

(There are two changes, (1) <li{0}> to <li> {proper html syntax} and (2) r["cat_id"] to cat_id {you already have it in a variable and string.Format doesn't mind recasting to a string for you})

Beyond that I would suggest looking into an ORM like LinqToSql so you could work directly with objects...

Answer 3

First render the category links in the master page:

** When you call GetAllProductCategories, each row of the result will have at least two columns (cat_id and cat_name).

When you get each row by index (var r = listSubMenu.Rows[i]) the row it returns will have the cat_id and cat_name for that record, I added (var name = r["cat_name"]) for illustration.

If you debug this and step through you should see each iteration through the for loop gives the id variable the next category's id which is then used in the line (var count = __account.GetSpecificCategory(id);)

var listSubMenu = __account.GetAllProductCategories();
var sb = new StringBuilder();
for (int i = 0; i < listSubMenu.Rows.Count; i++)
{
    var r = listSubMenu.Rows[i];

    var id = Int32.Parse(r["cat_id"]);
    var name = r["cat_name"];

    var count = __account.GetSpecificCategory(id);

    sb.AppendFormat(String.Format(@"<li{0}><a href='/account/products.aspx?categoryid={0}'>{1} ({2})</a></li>", r["cat_id"], r["cat_name"], count.Rows.Count));

}
active_sub_products.Text = sb.ToString();

Then into another textbox or area of the actual page "products.aspx"

var sbProducts = new StringBuilder();
var selectedCat = Request.QueryString["categoryid"];

if(!string.IsNullOrWhitespace(selectedCat))
{
    var selectedCatId = Int32.Parse(selectedCat);
    var products = __account.GetSpecificCategory(selectedCatId);

    for(int j = 0; j < products.Rows.Count; j++)
    {
         // ... do product listing stuff here
         // sbProducts.Append(...);
    }
}
else
{
    sbProducts.AppendLine("Invalid Category Id Selected!");
}
active_selected_products.Text = sbProducts.ToString();

** Note: when you call Request.QueryString["value"] it will either:

1. Return null indicating that there isn't a querystring parameter with a matching name

   or

2. Return the string representing the content between value= and the end of the url or the next & found.

** this isn't fully production quality code, there are additional checks you should be doing on the query string value, switch to tryparse for example, check number of products returned and show "No products found for that category" ... etc **