来自自引用表的 Laravel ORM 获得 N 级层次结构 JSON
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Laravel ORM from self referencing table get N level hierarchy JSON
提问by Dev
I am using LARAVEL 4with MySQLback-end.
我使用LARAVEL 4与MySQL后端。
I have a self-referencingtable with columns id, name, typeand parent.
Here, parentis foreign-keyof the column Id. The data in table is as below :
我有一个self-referencing带有列id, name, type和parent. 这里，parent是foreign-key列Id。表中数据如下：
id name type parent
1 General group NULL
2 What is..? question 1
3 aa answer 2
4 bb answer 2
5 cc answer 2
6 How is..? question 1
7 ba answer 6
8 bb answer 6
9 Where is..? question 4
10 ca answer 9
11 cb answer 9
12 Who is..? question 6
13 da answer 12
14 db answer 12
15 Specific group NULL
16 When is..? question 15
17 ea answer 16
18 eb answer 16
19 Whome is..? question 2
20 fa answer 19
21 fb answer 19
22 fc answer 19
I want a function that return nested JSONusing this relational data. For example :
我想要一个nested JSON使用此关系数据返回的函数。例如 ：
[{
"id" : 1,
"name" : "Geneal",
"type" : "group",
"children" : [{
"id" : 2,
"name" : "What is..?",
"type" : "question",
"children" : [{
"id" : 3,
"name" : "aa",
"type" : "answer"
},
{
"id" : 4,
"name" : "bb",
"type" : "answer"
},
{
"id" : 5,
"name" : "cc",
"type" : "answer"
}]},
{
"id" : 6,
"name" : "How is..?",
"type" : "question",
"children" : [{
"id" : 7,
"name" : "ba",
"type" : "answer"
},
{
"id" : 8,
"name" : "bb",
"type" : "answer"
}]
}]
... and so on
}]
I have created a modelnamed Surveyas below :
我创建了一个model命名Survey如下：
class Survey extends BaseModel{
protected $table = 'questions';
protected $softDelete = false;
public function parent()
{
return $this->belongsTo('Survey', 'parent');
}
public function children()
{
return $this->hasMany('Survey', 'parent');
}
}
and called it in controllerwith :
并调用它controller：
$user = Survey::all();
$parent = $user->parent()->first();
$children = $user->children()->get();
But I am not getting the proper result as I have mentioned in JSONabove.
但是我没有得到JSON上面提到的正确结果。
print_r($parent->toJson());
gives records with one level hierarchy only (i.e group and questions, not answers).
仅提供具有一级层次结构的记录（即组和问题，而不是答案）。
while
尽管
print_r($children ->toJson());
Gives only questions (Not groups and answers).
只给出问题（不是分组和答案）。
I want the whole self-referencing data in nested JSON format with N level of hierarchy.
我想要嵌套 JSON 格式的整个自引用数据，具有 N 级层次结构。
I also have tried
我也试过
$user = Survey::with('parent', 'children')->get();
But found same as $parent above.
但发现与上面的 $parent 相同。
Is there anyway I can get the desired result?
无论如何我能得到想要的结果吗？
Thanks in advance..
提前致谢..
回答by Jarek Tkaczyk
Here's how you manually retrieve nested relations:
以下是手动检索嵌套关系的方法：
$collection = Model::with('relation1.relation2.relation3')->get();
So in your case it would be:
所以在你的情况下，它将是：
$surveys = Survey::with('children.children.children')->get();
Obviously this will do the job when the relations are fixed, but it's not the way to go for a recursive relation to the same table.
显然，当关系固定时，这将完成工作，但这不是对同一张表建立递归关系的方法。
Fortunately, you can make such relation recursive, then all you need to retrieve whole tree is this:
幸运的是，你可以使这种关系递归，那么你需要检索整个树是这样的：
$surveys = Survey::with('childrenRecursive');
However, I wouldn't load parent for each row this way.
但是，我不会以这种方式为每一行加载父级。
So here's all you need:
所以这就是你所需要的：
// Survey model
// loads only direct children - 1 level
public function children()
{
return $this->hasMany('Survey', 'parent');
}
// recursive, loads all descendants
public function childrenRecursive()
{
return $this->children()->with('childrenRecursive');
// which is equivalent to:
// return $this->hasMany('Survey', 'parent')->with('childrenRecursive);
}
// parent
public function parent()
{
return $this->belongsTo('Survey','parent');
}
// all ascendants
public function parentRecursive()
{
return $this->parent()->with('parentRecursive');
}
EDIT: To get real tree structure, first query must be limited to only root nodes:
编辑：要获得真正的树结构，第一次查询必须仅限于根节点：
$surveys = Survey::with('childrenRecursive')->whereNull('parent')->get();
回答by ??????? ????
so simple!!!
很简单！！！
1- load your 'children' relation in your 'children' relation in your model like this :
1- 像这样在模型中的“孩子”关系中加载“孩子”关系：
class Survey extends BaseModel{
protected $table = 'questions';
protected $softDelete = false;
public function parent()
{
return $this->belongsTo('Survey', 'parent');
}
public function children()
{
// change this: return $this->hasMany('Survey', 'parent');
return $this->hasMany('Survey', 'parent')->with('children);
}
}
2- you just need add clouserfunction to your relation like this:
2- 你只需要像这样向你的关系添加clouser函数：
$surveys = Survey::with(['children' => function($q) {
$q->with('children');
},
'parent' => function($q) {
$q->with('parent');
});
then you can access to your nested children in your result like this:
然后您可以像这样访问结果中的嵌套子项：
$surveys->children
and unlimited nesting :
和无限嵌套：
$surveys->children->first()->children
and so on.
等等。
