使用javascript和ajax中的不细心！！！

在写一个提交的jsp时，由于var ?? = $("#??").val();这些写个方法写成了var
?? = $("#??"); 于是不仅不能判断表单是否存在空字段

更是每一次都报 Data truncated for column ' ' at row 1 这个错。整整一天！！这就是作为初学的菜鸟还不细心的下场。

另外，这个Data truncated for column ' ' at row 1 错误是由于写入数据库中的字符和数据中的该字段的类型不一致，或者为空字串，等等。我的数据中为double，传入为空的话即 “ ” ，就会报这个错，希望对大家找bug有帮助。

js部分：

$("#addSubmit").click(function() {
var prealertId = $("#prealertId")<span style="color:#ff0000;">.val();</span>
var itemName = $("#ItemName")<span style="color:#ff0000;">.val();</span>
var price = $("#Price")<span style="color:#ff0000;">.val()</span>;
var piece = $("#Piece")<span style="color:#ff0000;">.val();</span>
var declareValue = $("#DeclareValue")<span style="color:#ff0000;">.val();</span>
//alert(prealertId + " " + itemName + "　" + price + " " + piece + " " +  declareValue);

if(itemName == null || itemName == "" || piece == null || piece == ""
|| price == null || price == "" || declareValue == null || declareValue == ""
){
alert("Please fill in the information complete.");
}else {
$.ajax({
type : "post",
url : "customer/addItem",
data: {
"prealertId": prealertId,
"itemName" : itemName,
"price" : price,
"piece" : piece,
"declareValue" : declareValue
},
datatype : "text/html;charset=utf-8",
success : function(msg) {
if (msg == "error") {
<span style="white-space:pre">	</span>//alert("err");
location.href= "customer/modifyAddItem?prealertId="+prealertId
}
<span style="white-space:pre">	</span>		if (msg == "success") {
<span style="white-space:pre">		</span>//alert("su");
<span style="white-space:pre">	</span>location.href= "customer/modifyUpdate?prealertId="+prealertId
<span style="white-space:pre">		</span>}
<span style="white-space:pre">	</span>}
});
}
})

html-form部分：

<form id="addItemForm"  method="post">
<span style="color:#ff0000;"><input id="prealertId" type="hidden" name="prealertId" value="${prealertId}"/></span>

<div class="field-wrapper full-width">
<div class="label-column">
<label for="ItemName">Item Name</label>
</div>
<div class="field-column">
<span style="color:#ff0000;"><input type="text"  name="itemName" id="ItemName" data-val-required="Item Name is required." data-val="true"></span>
<span data-valmsg-replace="true" data-valmsg-for="ItemName" class="field-validation-valid"></span>
</div>
</div>
<div class="field-wrapper full-width">
<div class="label-column">
<label for="Price">Price</label>
</div>
<div class="field-column">
<span style="color:#ff0000;"> <input type="text" name="price" id="Price" data-val-required="Name is required." data-val="true"></span>
<span data-valmsg-replace="true" data-valmsg-for="Price" class="field-validation-valid"></span>
</div>
</div>
<div class="field-wrapper full-width">
<div class="label-column">
<label for="Piece">Piece</label>
</div>
<div class="field-column">
<span style="color:#ff0000;"><input type="text" name="piece" id="Piece" data-val-required="Piece is required." data-val="true"></span>
<span data-valmsg-replace="true" data-valmsg-for="Piece" class="field-validation-valid"></span>
</div>
</div>
<div class="field-wrapper full-width">
<div class="label-column">
<label for="DeclareValue">DeclareValue</label>
</div>
<div class="field-column">
<span style="color:#ff0000;"><input type="text" name="declareValue" id="DeclareValue"></span>
<span data-valmsg-replace="true" data-valmsg-for="DeclareValue" class="field-validation-valid"></span>
</div>
</div>
<span style="color:#ff0000;">  <button id="addSubmit" class="btn colored" type="button"><i class="fa fa-save btn-ico"></i> Save Item</button></span>
</form>