PHP在JSON数组中传回一个带有特殊字符的对象

Question

All, I have a php file which runs a MYSQL query and places the result in an array. The table has several fields, one has the characters '-' and '%' as part of a varchar string. When I pass this back in a JSON array it simply dies. Here are the code sections..

PHP file

// fetch merit guidelines
$meritGuideline = array();
$sql = "SELECT smg.id, year, ea.rating, ratioUpper, ratioLower, guideline, guidelineNum FROM spot_merit_guide smg JOIN epm_annual ea ON ea.id = smg.rating WHERE year = '$spotYear'";
$query = mysqli_query($con, $sql);
while ($row = mysqli_fetch_assoc($query)) {
    $meritGuideline[] = $row;
}
mysqli_free_result($query);

Then I return it with this

echo json_encode(array('meritGuideline' => $meritGuideline));

The mysql table field guideline contains the string 0 - 4%.

Answer 1

First, try encoding the data to UTF-8:

// fetch merit guidelines
$meritGuideline = array();
$sql = "SELECT smg.id, year, ea.rating, ratioUpper, ratioLower, guideline, guidelineNum FROM spot_merit_guide smg JOIN epm_annual ea ON ea.id = smg.rating WHERE year = '$spotYear'";
$query = mysqli_query($con, $sql);
while ($row = mysqli_fetch_assoc($query)) {
    $meritGuideline[] = utf8_encode($row); // ENCODE TO UTF-8
}
mysqli_free_result($query);

Then run this for debug purposes:

echo json_encode(array('meritGuideline' => $meritGuideline));
echo 'Error: ' . json_last_error_msg();

1. If the first line above does output your JSON, then the problem was most likely a hidden UTF-8 only special/invisible space character, which are often mischievous when dealing with JSON encoding or even Javascript code parsing in the browser. Here are some examples of these "special" space characters:

   No-break space: http://www.fileformat.info/info/unicode/char/00a0/index.htm

   Zero-width space: http://www.fileformat.info/info/unicode/char/200b/index.htm

2. If the first line still doesn't output anything, then the second line will allow you to see the exact error that's happening inside PHP's JSON encoder.