1

我的控制器中有以下逻辑：

public function showvlans()
{
    $vlans=$this->switches_model->show_known_vlans($this->uri->segment(5), $this->uri->segment(4));
    //filter out VLAN 1 if its included in the list. 
    $key = array_search('1', $vlans);
    unset($vlans[$key]);
    header ('Content-Type: application/json; charset=UTF-8');
    echo json_encode($vlans);  

} // end showvlans

出于某种原因，在我从数组中过滤掉一条记录后，我循环遍历 json 数据的逻辑不再起作用。

以下是遍历 json 数据的逻辑：

alert(returnDataFromController.length);
//loop through results
for(i = 0; i < returnDataFromController.length; i++) {
    alert(returnDataFromController[i].VlanId);
    htmlstring = htmlstring +  "<tr><td><a href=>"+returnDataFromController[i].VlanId+"</a></td><td>"+ returnDataFromController[i].Name+"</td></tr>";                         
}

线索：

警报显示“未定义”。
我还在从数组中删除记录之前和之后转储了数据，这是 json 数据的样子：

删除记录之前： 

[09:36:52.986] [
    {VlanId:"1", Name:"VLAN1", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"3", Name:"VLAN3", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"8", Name:"VLAN8", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"16", Name:"VLAN16", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"20", Name:"VLAN20", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"33", Name:"VLAN33", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"64", Name:"VLAN64", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"65", Name:"VLAN65", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"66", Name:"VLAN66", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"80", Name:"VLAN80", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"96", Name:"VLAN96", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"101", Name:"VLAN101", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"128", Name:"VLAN128", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"131", Name:"VLAN131", Status:"Port-based", Voice:"No", Jumbo:"No"},
    {VlanId:"417", Name:"VLAN417", Status:"Port-based", Voice:"No", Jumbo:"No"}]

后：

[09:34:41.797] (
    {1:{VlanId:"3", Name:"VLAN3", Status:"Port-based", Voice:"No", Jumbo:"No"},
     2:{VlanId:"8", Name:"VLAN8", Status:"Port-based", Voice:"No", Jumbo:"No"},
     3:{VlanId:"16", Name:"VLAN16", Status:"Port-based", Voice:"No", Jumbo:"No"},
     4:{VlanId:"20", Name:"VLAN20", Status:"Port-based", Voice:"No", Jumbo:"No"},
     5:{VlanId:"33", Name:"VLAN33", Status:"Port-based", Voice:"No", Jumbo:"No"},
     6:{VlanId:"64", Name:"VLAN64", Status:"Port-based", Voice:"No", Jumbo:"No"},
     7:{VlanId:"65", Name:"VLAN65", Status:"Port-based", Voice:"No", Jumbo:"No"},
     8:{VlanId:"66", Name:"VLAN66", Status:"Port-based", Voice:"No", Jumbo:"No"},
     9:{VlanId:"80", Name:"VLAN80", Status:"Port-based", Voice:"No", Jumbo:"No"},
     10:{VlanId:"96", Name:"VLAN96", Status:"Port-based", Voice:"No", Jumbo:"No"},
     11:{VlanId:"101", Name:"VLAN101", Status:"Port-based", Voice:"No", Jumbo:"No"},
     12:{VlanId:"128", Name:"VLAN128", Status:"Port-based", Voice:"No", Jumbo:"No"},
     13:{VlanId:"131", Name:"VLAN131", Status:"Port-based", Voice:"No", Jumbo:"No"},
     14:{VlanId:"417", Name:"VLAN417", Status:"Port-based", Voice:"No", Jumbo:"No"}})

如您所见，它看起来确实略有不同。在我使用 unset 之前我有一个开口[，而在我使用(. 我试图改变我的循环控制，以便变量i开始于1......但这也不起作用。

因此，例如，我尝试了以下操作：

for(i = 1; i < returnDataFromController.length; i++) {

代替

for(i = 0; i < returnDataFromController.length; i++) {
4

2 回答 2

1

假设您的数组以 5 个项目开始。当所有 5 项都存在时，数组键为：0、1、2、3、4

json_encode正确地将其检测为枚举数组，并将其转换为 JSON 数组。

但是，假设您删除了索引 2 处的项目。现在，您有：0、1、3、4。json_encode看到键的非连续编号，现在假设它是一个关联数组，因此您返回一个 JSON 对象键 0、1、3、4。JSON/Javascript 中的对象没有length，因此您的代码不再有效。

诀窍是array_values在将它传递给之前使用json_encode，如果你想将它枚举为一个数组。

或者，您可以将forJavaScript 中的循环更改为：

for (var i in returnDataFromController) {
    if (returnDataFromController.hasOwnProperty(i)) {
        /* your code here */
    }
}

虽然强烈建议通过将其转换为数组array_values

于 2013-01-24T14:59:42.887 回答
1

Javascript/JSON 区分对象和数组。对象是使用语法的键值对{ }，数组是使用[ ].

使用json_encodePHP 数组时，只有具有连续数字索引的数组才会被编码为 JSON/Javascript数组，否则它们将成为对象。例如：

array('foo', 'bar', 'baz')    -> ["foo", "bar", "baz"]
array(0 => 'foo', 2 => 'bar') -> {"0":"foo", "2":"bar"}

要确保您的数组具有连续的数字索引，请使用array_values.

于 2013-01-24T15:02:16.660 回答