请教我的代码中的问题 ajax+php(CodeIgniter)

[海边的嘉楠]

我用ajax将页面的值传递到后台，但是却无法获取，请教下我这个该怎么写呢？麻烦大牛们了。

我的页面代码为：
<script type="text/javascript">
$(function() {
$("form[name='estimate']").submit(function(e) {
e.preventDefault();
var btn = $("form[name='estimate']").find("input[type='submit']"),
price = $(this).find(".price");
btn.button('loading');
price.html("");
$.ajax({
type: "POST",
url: '<?php echo base_url(); ?>index.php?module=testprice&view=getprice',
data: $(this).serializeArray(),
success: function(data) {
price.html("<h3>$" + data + " RMB</h3><h4>" + "</h4>");
btn.button('reset');
},
error: function() {
alert("Service Unavailable");
}
});
});

</script>

<!-- Body -->
<div id="body_section">
<div id="body_section_inner">
<div class="contentPageWrapper">
<div class="container-fluid">
<div id="dashboard">
<div class="row-fluid">
<div class="span12">
<h2>估算</h2>
</div>
</div>
<div class="row-fluid">
<form name="estimate" id="estimate" method="post" action="#" class="form-inline well well-small">
<div class="span9">
<h4>计算成本</h4>
<div class="row-fluid">
<div class="span12">
<div class="units control-group">
<div class="controls">
<label class="checkbox">
<small><input type="radio" name="units" value="Metric" checked="checked" autocomplete="off" /> 公制的 (kg, cm)</small>
</label>
  
<label class="checkbox">
<small><input type="radio" name="units" value="Imperial" autocomplete="off" /> 英制的 (oz, in)</small>
</label>
</div>
</div>
</div>
</div>
<div class="row-fluid">
<div class="span3">
<div class="control-group">
<label class="control-label" for="postal_code">邮政编码</label>
<div class="controls">
<input type="text" class="input-small" name="postal_code" id="postal_code" value="" maxlength="5" />
</div>
</div>
</div>
<div id="estimate">
<div class="span3">
<div class="control-group">
<label class="control-label" for="weight">重量</label>
<div class="controls">
<div class="input-append">
<input type="text" class="input-mini" name="weight" value="" maxlength="6" />
<span class="add-on">kg</span>
</div>
</div>
</div>
</div>
<div class="span6">
<label class="control-label" for="dimensions">尺寸</label>
<div class="clearfix"></div>
<div class="input-append">
<input type="text" class="input-micro" name="height" value="" maxlength="6" />
<span class="add-on">cm</span>
</div>
x
<div class="input-append">
<input type="text" class="input-micro" name="width" value="" maxlength="6" />
<span class="add-on">cm</span>
</div>
x
<div class="input-append">
<input type="text" class="input-micro" name="depth" value="" maxlength="6" />
<span class="add-on">cm</span>
</div>
</div>
</div>
</div>
<div class="row-fluid">
<div class="span5">
<div class="control-group">
<div class="controls">
<label class="checkbox">
<input type="checkbox" name="sc" value="1" autocomplete="off" /> fsd </label>
</div>
</div>
</div>
<div class="span7"></div>
</div>
</div>
<div class="span3">
<input type="submit" class="btn btn-inverse btn-large btn-block btn-estimate" value="" data-loading-text="" autocomplete="off" />
<div class="form-errors"></div>
<div class="price"></div>
</div>
</form>
</div>

</div>

</div>
</div></div>
</div>

我的后台代码如下：
function getUserPrice() {
$tozipcode_t = $_POST('postal_code');

}

我这里无论怎样都无法获取值，请大牛帮忙分析一下，多谢多谢了

[海边的嘉楠]

十分感谢。我真的很多不会，以后多和您请教了。

[xuzuning]

$tozipcode_t = $_POST['postal_code'];