从PHP中获取来自JSON数组的值(Get value from JSON array in PHP)

 我试图从这个PHP变量中的下面的JSON数组中获取值。 
 
 这是一个数组的var_dump： 
 
array(3) {
  ["id"]=>
  string(2) "14"
  ["css"]=>
  string(400) ""
  ["json"]=>
  string(4086) "
            {
                "Canvas": [
                    {
                        "MainObjects": {
                            "After Participation": {
                                "afterParticipationHeader": "Thank you!"
                            },
                            "Invite Friends": {
                                "InviteHeadline": "",
                                "InviteMsg": "",
                                "InviteImg": ""
                            }
                        },
                        "QuizModule": {
                            "Questions": [],
                            "Submit_Fields": [
                                {
                                    "label": "Name",
                                    "name": "txtName",
                                    "value": true
                                }
                            ]
                        }
                    }
                ]
            }"
        }
 
 我能够在PHP中获得[“json”]的值，如下所示： 
 
$json = $data[0]['json'];
 
 但是，如何从“json”内的数组中获取值，如“AfterParticipationHeader”。 和“Submit_Fields”？ 

I'm trying to get the value from this following JSON array in a PHP variable.
 
This is a var_dump of the array:
 
array(3) {
  ["id"]=>
  string(2) "14"
  ["css"]=>
  string(400) ""
  ["json"]=>
  string(4086) "
            {
                "Canvas": [
                    {
                        "MainObjects": {
                            "After Participation": {
                                "afterParticipationHeader": "Thank you!"
                            },
                            "Invite Friends": {
                                "InviteHeadline": "",
                                "InviteMsg": "",
                                "InviteImg": ""
                            }
                        },
                        "QuizModule": {
                            "Questions": [],
                            "Submit_Fields": [
                                {
                                    "label": "Name",
                                    "name": "txtName",
                                    "value": true
                                }
                            ]
                        }
                    }
                ]
            }"
        }
 
I am able to get the values for ["json"] in PHP like: 
 
$json = $data[0]['json'];
 
But how do I get the value from from the array inside "json", like "AfterParticipationHeader". And "Submit_Fields" ?

原文：https://stackoverflow.com/questions/17995877