list转json树结构

将一个列表转换为 JSON 树结构的方法，可以使用递归函数来实现。

假设我们有以下列表：

[
    {"id": 1, "name": "node1", "parent_id": null},
    {"id": 2, "name": "node2", "parent_id": 1},
    {"id": 3, "name": "node3", "parent_id": 1},
    {"id": 4, "name": "node4", "parent_id": 3},
    {"id": 5, "name": "node5", "parent_id": 2}
]

我们可以先定义一个函数来获取指定节点的所有子节点：

def get_children(nodes, parent_id):
    return [node for node in nodes if node['parent_id'] == parent_id]

然后定义一个递归函数来将节点列表转换为 JSON 树结构：

def list_to_json_tree(nodes, parent_id=None):
    children = get_children(nodes, parent_id)
    if not children:
        return None
    tree = []
    for child in children:
        node = {
            'id': child['id'],
            'name': child['name'],
            'children': list_to_json_tree(nodes, child['id'])
        }
        tree.append(node)
    return tree

最后调用这个函数，将列表转换为 JSON 树结构：

import json

nodes = [
    {"id": 1, "name": "node1", "parent_id": None},
    {"id": 2, "name": "node2", "parent_id": 1},
    {"id": 3, "name": "node3", "parent_id": 1},
    {"id": 4, "name": "node4", "parent_id": 3},
    {"id": 5, "name": "node5", "parent_id": 2}
]

tree = list_to_json_tree(nodes)
json_tree = json.dumps(tree)
print(json_tree)

输出结果为：

[{
    "id": 1,
    "name": "node1",
    "children": [{
        "id": 2,
        "name": "node2",
        "children": [{
            "id": 5,
            "name": "node5",
            "children": null
        }]
    }, {
        "id": 3,
        "name": "node3",
        "children": [{
            "id": 4,
            "name": "node4",
            "children": null
        }]
    }]
}]