2015-07-05 18:53
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PHP JSON字符串转义双引号内有价值?

I'm getting a JSON string from an api like this :

{ "title":"Example string's with "special" characters" }

which is not json decodable by using json_decode (its output is null).

so I want to change it to something json decodable like :

{ "title":"Example string's with \"special\" characters" }


{ "title":"Example string's with 'special' characters" }

in order to make json_decode function work, what should I do ?

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  {“title”:“示例字符串带\”特殊\  “characters”} 

  {“title”:“带有'特殊'字符的示例字符串”  } 


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1条回答 默认 最新

  • dongshi2141 2016-05-25 16:10

    Since yesterday I was trying to solve this tricky problem, and after a lot of hair pulling I came up with this solution.

    First let us clarify our assumptions.

    • json string should be right formated.
    • The keys and values are quoted with double quotation.

    Analyzing the problem:

    We know that json keys formated like this (,"keyString":) and json value is (:"valueString",)

    keyString: is any sequence of characters except (:").

    valueString: is any sequence of characters except (",).

    Our goal is to escape quotations inside valueString, to achive that we need to separate keyStrings and valueStrings.

    • But we have also a valid json format like this ("keyString":digit,) this will cause a problem because it breaks out assumption that says values always ended with (",)
    • Another problem is having empty values like ("keyString":" ")

    Now after analyzing the problem we can say

    1. json keyString has (,") before it and (":) after it.
    2. json valueString can have (:") before and (",) after OR (:) before and digit as a value then (,) after OR (:) followed by (" ") then (,)

    The solution: Using this facts the code will be

    function escapeJsonValues($json_str){
      $patern = '~(?:,\s*"((?:.(?!"\s*:))+.)"\s*(?=\:))(?:\:\s*(?:(\d+)|("\s*")|(?:"((?!\s*")(?:.(?!"\s*,))+.)")))~';
      //remove { }
      $json_str = rtrim(trim(trim($json_str),'{'),'}');
      if(strlen($json_str)<5) {
        //not valid json string;
        return null;
      //put , at the start nad the end of the string
      $json_str = ($json_str[strlen($json_str)-1] ===',') ?','.$json_str :','.$json_str.',';
      //strip all new lines from the string
      preg_match_all($patern, $json_str, $matches);
            //value is digit
            //no value
            elseif (strlen($matches[3][$i])>0) {
            //text, and now we can see if there is quotations it will be related to the text not json
            //so we can add slashes safely
            //also foreword slashes should be escaped 
                $json.='"'.str_replace(['\\','"' ],['/','\"'],$matches[4][$i]).'",';
      return trim(rtrim($json,','),',').'}';

    Note: The code realizes white spaces.

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