blocks|key|758153|text|我将添加到公认的答案中，因为只有当你有一个一维的对象或数组时，它才会起作用。如果有任何数组或对象嵌套，那么为了让接受的解决方案工作，您必须创建某种递归数组过滤器。不是很理想。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|758154|我和我的同事提出的最好的解决方案是在从服务器返回JSON字符串之前对其执行正则表达式。|758155|$json+=+json_encode($complexObject);
echo+preg_replace('/,\s*"[%5E"]%2B":null%7C"[%5E"]%2B":null,?/',+'',+$json);|code-block|syntax|javascript|758156|正则表达式将删除形式为,"key":null的字符串中的所有位置，包括前导逗号和键开头之间的任何空格。之后，它还将匹配"key":null,，以确保在JSON对象的开头没有找到空值。|offset|length|style|CODE|758157|这不是一个理想的解决方案，但它比创建一个递归数组过滤器要好得多，因为一个对象可能有几个维度深。一个更好的解决方案是，如果json_encode有一个标志，让您指定是否希望空条目保留在输出字符串中。|758158|entityMap^0|0|0|0|B|B|1N|B|0|1O|B|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]|$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@$K|11|L|12|M|N]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|13|8|@]|9|@]|A|$]]]|R|$]]

I'm going to add to the accepted answer because that will only work if you have a 1 dimensional object or array. If there is any array or object nesting then in order to get the accepted solution to work, you must create some sort of recursive array filter. Not ideal.

The best solution my colleague and I came up with was to actually perform a regular expression on the JSON string before it was returned from the server.

<pre><code>$json = json_encode($complexObject);
echo preg_replace('/,\s*"[^"]+":null|"[^"]+":null,?/', '', $json);
</code></pre>

The regular expression will remove all places in the string of the form <code>,"key":null</code> including any whitespace between the leading comma and the start of the key. It will also match <code>"key":null,</code> afterwards to make sure that no null values were found at the beginning of a JSON object.

This isn't an ideal solution but it's far better than creating a recursive array filter given an object could be several dimensions deep. A better solution would be if <code>json_encode</code> had a flag that let you specify if you wanted null entries to remain in the output string.

blocks|key|541674|text|在Javascript端使用原生JSON.stringify方法怎么样？您可以设置第二个参数，即删除具有空值的键的函数。如果返回undefined，则该属性不包含在输出JSON字符串中(请查看https://developer.mozilla.org/en-US/docs/Using_native_JSON#The_replacer_parameter上的文档中的“replacer参数”)。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|541675|function+removeNulls(obj)+{
++++var+str+=+JSON.stringify(obj,+function(key,+val)+{
++++++++if+(val+==+null)+return+undefined;
++++++++return+val;
++++});
++++return+JSON.parse(str);
}|code-block|syntax|javascript|541676|然后，您可以通过调用以下命令来拥有一个“标准化的”JSON对象：|541677|var+obj+=+removeNulls(obj);|541678|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Using_native_JSON#The_replacer_parameter^0|2O|29|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@]|9|@]|C|$]]|$1|K|3|L|5|F|7|10|8|@]|9|@]|C|$G|H]]|$1|M|3|-4|5|6|7|11|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

What about using the native JSON.stringify method on the javascript side?
You can set, a second parameter, a function to remove keys with a null value.
If you return undefined, the property is not included in the output JSON string (check the documentation for "the replacer parameter" at <a href="https://developer.mozilla.org/en-US/docs/Using_native_JSON#The_replacer_parameter" rel="nofollow">https://developer.mozilla.org/en-US/docs/Using_native_JSON#The_replacer_parameter</a>).

<pre><code>function removeNulls(obj) {
 var str = JSON.stringify(obj, function(key, val) {
 if (val == null) return undefined;
 return val;
 });
 return JSON.parse(str);
}
</code></pre>

Then you can have a "normalized" JSON object by calling:

<pre><code>var obj = removeNulls(obj);
</code></pre>

blocks|key|758285|text|public+function+__toString()+{
++++$obj+=+clone+$this;
++++$keys+=+get_object_vars($obj);
++++foreach+($keys+as+$key+=>+$value)+{
++++++++if+(!$value)+{
++++++++++++unset($obj->{$key});
++++++++}
++++}
++++return+json_encode($obj);
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|758286|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>public function __toString() {
 $obj = clone $this;
 $keys = get_object_vars($obj);
 foreach ($keys as $key =&gt; $value) {
 if (!$value) {
 unset($obj-&gt;{$key});
 }
 }
 return json_encode($obj);
}
</code></pre>

blocks|key|758290|text|echo+json_encode(array_filter((array)+$object,+function($val)+{
++++return+!empty($val);
}));|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|758291|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>echo json_encode(array_filter((array) $object, function($val) {
 return !empty($val);
}));
</code></pre>

blocks|key|758326|text|class+Foo+implements+JsonSerializable
{
++++public+$param1;
++++public+$param2;
++++
++++public+function+jsonSerialize()
++++{
++++++++return+array_filter((array)+$this,+function+($var)+{
++++++++++++return+!is_null($var);
++++++++});
++++}
}

public+function+testJsonSerialization()
{
++++$expectedJson+=+'{"param1":true}';

++++$foo+=+new+Foo();
++++$foo->param1+=+true;
++++$foo->param2+=+null;

++++$this->assertEquals(
++++++++$expectedJson,
++++++++json_encode($foo)
++++);
}`|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|758327|当然，您可以使用自定义jsonSerialize方法创建抽象类，并由此扩展所有DTO|unstyled|758328|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>class Foo implements JsonSerializable
{
 public $param1;
 public $param2;
 
 public function jsonSerialize()
 {
 return array_filter((array) $this, function ($var) {
 return !is_null($var);
 });
 }
}

public function testJsonSerialization()
{
 $expectedJson = '{&quot;param1&quot;:true}';

 $foo = new Foo();
 $foo-&gt;param1 = true;
 $foo-&gt;param2 = null;

 $this-&gt;assertEquals(
 $expectedJson,
 json_encode($foo)
 );
}`
</code></pre>
of course you can create Abstract class with custom jsonSerialize method and extend all your DTOs from this

All my AJAX requests are in json format which are being parsed in javascript.

How can i prevent null values being displayed in an HTML page without needing to write an if-statement in javascript for each json value? 

Or should i write a custom PHP function to encode an array to json instead of using json_encode() so it doesn't display 'null' ?

strip null values of json object

服务器

JSON

我所有的AJAX请求都是json格式的，都是用javascript解析的。如何避免在HTML页面中显示空值，而不需要在javascript中为每个json值编写if语句？或者我是否应该编写一个自定义的PHP函数来将数组编码为json，而不是使用json_encode()，这样它就不会显示“null”？

问剥离json对象的空值
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