c# - Shopping cart displays records twice -


problem when same item added cart again display same record of same product twice, here want when press add cart button twice or 3 time should increment quantity of same item.

protected void addtocartbutton_click(object sender, eventargs e) {     if (con.state == connectionstate.open)     {         con.close();     }     con.open();     sqlcommand cmd = con.createcommand();     cmd.commandtype = commandtype.text;     book_id = convert.toint32(request.querystring["book_id"].tostring());     cmd.commandtext = "select * book book_id = " + book_id + "";     cmd.executenonquery();     datatable dt = new datatable();     sqldataadapter sda = new sqldataadapter(cmd);     sda.fill(dt);     foreach (datarow dr in dt.rows)     {                          //book_id =convert.toint32(dr["book_id"]);         title = dr["title"].tostring();         //quantity = dr["quantity"].tostring();         quantity = quantitytxt.text;         price = dr["price"].tostring();     }     //restrict user enter quantity wants...     if(convert.toint32(quantitytxt.text)>convert.toint32(quantity))     {         errormsglbl.text = "please enter lower quantity";     }     else     {         errormsglbl.text = "";     }     // creating cookies store value , assign data table...       if (request.cookies["shoppingcart"] == null)     {         response.cookies["shoppingcart"].value = book_id.tostring() + "," + title.tostring() + "," + quantity.tostring() + "," + price.tostring();         response.cookies["shoppingcart"].expires = datetime.now.adddays(1);     }     else     {         response.cookies["shoppingcart"].value = request.cookies["shoppingcart"].value + "|" + book_id.tostring() + "," + title.tostring() + "," + quantity.tostring() + "," + price.tostring();         response.cookies["shoppingcart"].expires = datetime.now.adddays(1);     }      response.redirect("bookdetails.aspx?book_id="+book_id.tostring()+"&cat_id="+viewstate["cat"]+"");  }// end add cart button...

problem lies in else block

 response.cookies["shoppingcart"].value = request.cookies["shoppingcart"].value +  "|" + book_id.tostring() + "," + title.tostring() +  "," + quantity.tostring() + "," + price.tostring();

here assigning previous cookie value new cookie along new content. e.g. if have "1, shoe, 1,25" in cookie , add same product cart again "1, shoe, 1,25| 1,shoe, 1,25".

this problem can solved multiple approaches

  1. split cookies , check book_id value
  2. use object store cart item , save them in session.

approach first

string[] carts = request.cookies["shoppingcart"].value.split("|") bool bookidexists = false; foreach(string cartdetail in carts) {   string  bookid = cartdetail.split(",")[0];   if(bookid == newbookid)   {     bookidexists = true;   } } if(!bookidexists) {   //add new item cookie }

second approach

public class cart {   public int bookid {get; set;}   public string title {get; set;}   public int qty {get; set;}   public decimal price {get; set} }  list<cart> carts =session["cart"]==null? new list<cart>(): session["cart"] list<cart>; var existingcart = carts.where(x=> x.bookid==newbookid).firstordefault(); if(existingcart==null) {   cart c= new cart {   bookid = newbookid,   title =newtitle,   qty = newqty,   price =newprice };  carts.add(c);  session["cart"] = carts; }

you may come better approach solve problem.

but terrible idea use cookie store cart details.


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