In PHP code, print_r() can output data normally, while return json() returns blank. What is the reason?

php print_r can output data normally, but return json() is displayed as blank. What is the reason?

In the problem description, the developer successfully printed the content of the $response variable using print_r($response), indicating that the variable contains valid data. However, when using return json($response) the result is blank. The code snippet shows how to use otsclient->search() to get data, and then use print_r() and return json() to process the results respectively.

The key problem is that the json() function is used in the code, which is not a standard function used in JSON encoding in PHP. The json encoding function of php is json_encode(), not json(). The json() function is likely not present, or is defined in a custom function library, but its function is different from json_encode(), resulting in the inability to correctly encode the $response variable.

So the workaround is to replace return json($response) with return json_encode($response). The json_encode() function converts a php array or object into a string in json format, so that it can be correctly parsed by the front-end. If the problem still occurs, check if the data structure of the $response variable is suitable for json encoding, such as if it contains resources or objects that cannot be encoded. In addition, it is also recommended to check the data type returned by the $otsclient->search() method to make sure it is a php array or object, not other types of data.

The modified code is as follows:

 $request_info = array(
    'table_name' => 'x_net_worth',
    'index_name' => 'x_net_worth_index',
    'search_query' => array(
        'offset' => 0,
        'limit' => 100,
        'get_total_count' => true,
        'query' => array(
            'query_type' => QueryTypeConst::MATCH_ALL_QUERY
        ),
        'sort' => array(
            array(
                'field_sort' => array(
                    'field_name' => 'networth_timestamp',
                    'order' => SortOrderConst::SORT_ORDER_DESC
                )
            ),
        ),
        'token' => null,
    ),
    'columns_to_get' => array(
        'return_type' => ColumnReturnTypeConst::RETURN_ALL,
    )
);
$response = $otsClient->search($request_info);

print_r($response); // Get the data normally. return json_encode($response); // JSON data should be returned.

By using json_encode(), the problem of blank return should be solved. If the problem persists, you need to further check the content of the $response variable and the return value of the otsclient->search() method.

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