Question

我有sell.php和sell_form.php文件。他们在销售方面做得很好，但是如果他们为股票代码选择一个空值，我想尝试给用户一个错误信息。我已经实施了

'if(["blank"]){
        apologize("You must select a stock symbol");
    }'

我收到带有此if语句的错误消息，但我也无法出售所选股票。我不知道我在哪里弄错了。我也试过使用这个if语句

'if([empty($_POST["symbol"])){
        apologize("You must select a stock symbol");
    }'

这会将我重定向到主页，没有错误。任何帮助，将不胜感激。这是我的两个文件的代码。 sell.php

//configuration
require("../includes/config.php");

if ($_SERVER["REQUEST_METHOD"] == "POST") 
{

    if(empty($_POST["symbol"])){

        apologize("You must select a stock symbol");

    }  

    // lookup stock
    $stock = lookup($_POST["symbol"]);

    // lookup user's shares of stock being sold
    $shares = query("SELECT shares FROM shares WHERE id = ? AND symbol = ?",  $_SESSION["id"], $_POST["symbol"]);

    // calculate total sale value (stock's price * shares)
    $value = $stock["price"] * $shares[0]["shares"];

    $date = date("Y-m-d, H:i:s");

    // add the sale value to cash
    query("UPDATE users SET cash = cash + ? WHERE id = ?", $value, $_SESSION["id"]);

    // delete the stock from their portfolio 
    query("DELETE FROM shares WHERE id = ? AND symbol = ?", $_SESSION["id"], $_POST["symbol"]);  

    query("INSERT INTO history (id, symbol, soldOrBought, numberOfSharesBoughtOrSold, price, dateAndTime)
          VALUES (?, ?, 'Sold', ?, ?, ?)", $_SESSION["id"], strtoupper($_POST["symbol"]), $shares[0]["shares"], $stock["price"], $date );



redirect("/");
}
else
{

$rows = query("SELECT * FROM shares WHERE id = ?", $_SESSION["id"]);

    //create array to store the shares
    $shares = [];

    //for each of the user info

    foreach($rows as $row){

        //lookup stock info
        $stock = lookup($row["symbol"]);
        if($stock !== false){

            $shares[] = [
                "name" => $stock["name"],
                "price" => $stock["price"],
                "shares" => $row["shares"],
                "symbol" => $row["symbol"],
                "total" => $row["shares"]*$stock["price"]
            ];

        }
    }

// render portfolio
render("sell_form.php", ["shares" => $shares, "title" => "Sell"] );
}

?>

sell_form.php

<ul class="nav nav-pills" >

<li >
    <a href="index.php">Portfolio</a>
</li>
<li>
    <a href="quote.php">Quote</a>
</li>
<li>
    <a href="buy.php">Buy</a>
</li>
<li>
    <a href="sell.php">Sell</a>
</li>
<li>
    <a href="history.php">History</a>
</li>
<li>
    <a href="deposit.php">Deposit Funds</a>
</li>    

</ul>
<form action="sell.php" method="post">
<fieldset>     
    <div class="control-group">

        <select name="symbol">
        <option value="blank"></option>

        <?php foreach ($shares as $symbol):?>
        <option value="<?= $symbol["symbol"]?>"><?= $symbol["symbol"]?></option>
         <? endforeach ?>
        </select>     

    </div>
    <div class="control-group">
        <button type="submit" class="btn">Sell all shares</button>
    </div>
</fieldset>
</form>
<div>
or <a href="logout.php">log out</a>
</div>

Answer 1

您的选择列表可以包含“空白”选项，值为“空白”，因此检查空白不会对表单的常规帖子起作用。

您的支票应该是：

if(empty($_POST["symbol"]) || $_POST["symbol"]=="blank") {

    apologize("You must select a stock symbol");

}

现在，当值完全丢失或值为“空白”时，它将显示此消息。另一种选择是改变选择列表以获得第一个选项，如

<select name="symbol">
<option value=""></option>

然后您只需检查if (empty($_POST["symbol"])) { }

Answer 2

根据我的理解，函数apologize（）正在打印输入文本，然后你必须在调用该函数后终止执行。这样你就可以得到错误信息。试试如下，

if(empty($_POST["symbol"])){
apologize("You must select a stock symbol");
die();
}

编辑：为了更好地理解，也可以发布apologize（）定义。

在php中检查空选择不会给出正确的结果

2 个答案: