为返回为 JSON 的分层数据创建用户定义函数

Question

这是. I have Departments table which uses HierarchyId存储分层数据。

Id	HieararchyId	Name
1	/	MHz
2	/2/	Finance
3	/3/	IT
4	/3/4/	Software Development
5	/3/5/	QA
6	/2/6/	Accountant

我想把这个 table 作为我的 TreeView 在前面的 JSON。

我做了什么：

CREATE FUNCTION dbo.GetDepartmentAsJson
    (@departmentId hierarchyid, 
     @IsRoot int)
RETURNS nvarchar(max)
AS
BEGIN
    DECLARE @Json NVARCHAR(MAX) = '{}',
            @Id int,
            @Name varchar(50),
            @Children NVARCHAR(MAX) = '{}',
            @Hierar Hierarchyid

    SET @Json = (SELECT 
                     t.Id, t.HierarchyId, t.Name,
                     children = JSON_QUERY(dbo.GetDepartmentAsJson(t.HierarchyId, 2))
                 FROM Departments t
                 WHERE t.HierarchyId <> @departmentId
                   AND t.HierarchyId.IsDescendantOf(@departmentId) = 1
                 FOR JSON PATH);

    IF (@IsRoot = 1) 
    BEGIN
        SELECT
            @Id = t.Id,
            @Hierar = t.HierarchyId,
            @Name = t.Name
        FROM 
            Departments t
        WHERE 
            t.HierarchyId = @departmentId;

        SET @Json = 
        '{"Id":"' + CONVERT(varchar(7), @Id) +
        '","HierarchyId":"' + @Hierar.ToString() + 
        '","Name":"' + @Name + 
        '","Children":' + CAST(@Json AS NVARCHAR(MAX)) + '}';
        SET @IsRoot = 2;
    END

    RETURN @Json;
END;

结果：

 {
  "Id": "1",
  "HierarchyId": "/",
  "Name": "MHz",
  "Children": [
    {
      "Id": 2,
      "HierarchyId": "/2/",
      "Name": "Finance",
      "Children": [
        {
          "Id": 6,
          "HierarchyId": "/2/6/",
          "Name": "Accountant"
        }
      ]
    },
    /* This should not be listed because already included as a child in Finance */
    {
      "Id": 6,
      "HierarchyId": "/2/6/",
      "Name": "Accountant"
    },
    {
      "Id": 3,
      "HierarchyId": "/3/",
      "Name": "IT",
      "Children": [
        {
          "Id": 4,
          "HierarchyId": "/3/4/",
          "Name": "Software Development"
        },
        {
          "Id": 5,
          "HierarchyId": "/3/5/",
          "Name": "QA"
        }
      ]
    },
    /* They both should not be listed because already included as a child in IT */
    {
      "Id": 4,
      "HierarchyId": "/3/4/",
      "Name": "Software Development"
    },
    {
      "Id": 5,
      "HierarchyId": "/3/5/",
      "Name": "QA"
    }
  ]
}

如何排除已在父元素中列出的子元素？

Answer 1

你也应该检查后代的等级

CREATE FUNCTION dbo.GetDepartmentAsJson(@departmentId hierarchyid, @level int)
RETURNS nvarchar(max)
AS
BEGIN
DECLARE @Json NVARCHAR(MAX) = '{}',
    @Id int,
    @Name varchar(50),
    @Childeren NVARCHAR(MAX) = '{}',
    @Hierar Hierarchyid

    SET @Json = (SELECT
    t.Id,
    t.HierarchyId,
    t.Name,
    children = JSON_QUERY(dbo.GetDepartmentAsJson(t.HierarchyId, @level + 1))
    FROM Departments t
    WHERE t.HierarchyId <> @departmentId
    AND t.HierarchyId.IsDescendantOf(@departmentId) = 1 and t.HierarchyId.GetLevel() =  @level + 1
    FOR JSON PATH);

    IF(@level = 0) 
    BEGIN
        SELECT
        @Id = t.Id,
        @Hierar = t.HierarchyId,
        @Name = t.Name
        FROM Departments t
        WHERE t.HierarchyId = @departmentId;

        SET @Json = 
        '{"Id":"' + CONVERT(varchar(7), @Id) +
        '","HierarchyId":"' + @Hierar.ToString() + 
        '","Name":"' + @Name + 
        '","Children":' + CAST(@Json AS NVARCHAR(MAX)) + '}';
    END

    return @Json;

  END;

The root of the hierarchy is level 0，所以select dbo.GetDepartmentAsJson ('/', 0)

db<>fiddle

为返回为 JSON 的分层数据创建用户定义函数

Create user defined function for Hierarchical data returning as JSON

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