How to Convert Tree Structure List to Json

Question

I have query result like this :

DEPT_NAME	DEPT_R_IDX	DEPT_IDX	DEPT_LEVEL
root	0	1	0
dept_0	1	2	1
dept_1	1	3	1
dept_1_0	3	4	2
dept_1_1	3	5	2
dept_2	1	6	1
dept_2_0	6	7	2
dept_2_0_1	7	8	3

DEPT_IDX is PRIMARY KEY, DEPT_LEVEL is TREE DEPTH, DEPT_R_IDX is parent's DEPT_IDX

I stored this data in Java's List.

List<HashMap<String, String>> DEPT_LIST;

I want convert this List to Json like this :

[
    {
        "title": "root",
        "key": "1",
        "expanded": true,
        "folder": true,
        "children": [
            {
                "key": "2",
                "title": "dept_0",
                "expanded": true,
                "folder": true
            },
            {
                "key": "3",
                "title": "dept_1",
                "expanded": true,
                "folder": true,
                "children": [
                    {
                        "key": "4",
                        "title": "dept_1_0",
                        "expanded": true,
                        "folder": true
                    },
                    {
                        "key": "5",
                        "title": "dept_1_1",
                        "expanded": true,
                        "folder": true
                    }
                ]
            },
            {
                "key": "6",
                "title": "dept_2",
                "expanded": true,
                "folder": true,
                "children": [
                    {
                        "key": "7",
                        "title": "dept_2_0",
                        "expanded": true,
                        "folder": true,
                        "children": [
                            {
                                "key": "8",
                                "title": "dept_2_1",
                                "expanded": true,
                                "folder": true
                            }
                        ]
                    }
                ]
            }

        ]
    }
]

result tree using this json data(using fancytree)

i tried this in browser side, but it's too low performance to make json structure

Usually we get POs(Persistant object) from database, and use json frameworks like jackson return the POs to frontend, we use @JsonProperty on field of PO to customize how to format one field — Hi computer, Jan 31 '23 at 06:32
I don\`t think it is a good idea that you save the data in a List> — Hi computer, Jan 31 '23 at 06:33

score 0 · Answer 1 · answered Jan 31 '23 at 06:33

Instead of storing your data in a List<HashMap<String, String>>, store them in a List<Node> where class Node is something like this:

public class Node {
    private String title;
    private String key;
    private boolean expanded;
    private boolean folder;
    private List<Node> children;

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getKey() {
        return key;
    }

    public void setKey(String key) {
        this.key = key;
    }

    public boolean isExpanded() {
        return expanded;
    }

    public void setExpanded(boolean expanded) {
        this.expanded = expanded;
    }

    public boolean isFolder() {
        return folder;
    }

    public void setFolder(boolean folder) {
        this.folder = folder;
    }

    public List<Node> getChildren() {
        return children;
    }

    public void setChildren(List<Node> children) {
        this.children = children;
    }
}

Then use Jackson or Gson to generate the corresponding Json.

How to Convert Tree Structure List to Json

1 Answers1