I want to convert flat structure array into a tree structure for one my projects. Below is the input and expected output:

Input:

let input=[
    {
        lvl1:"Code1",
        lvl2:"Type1",
        lvl3:"Desc1",
        lvl4:"Check1"
    },
    {
        lvl1:"Code1",
        lvl2:"Type1",
        lvl3:"Desc1",
        lvl4:"Check2"
    },
    {
        lvl1:"Code2",
        lvl2:"Type2",
        lvl3:"Desc2",
        lvl4:"Check1"
    },
]

Output:

[
    {
        level_key:"lvl1",
        level_value:"Code1",
        children:[
            {
                level_key:"lvl2",
                level_value:"Type1",
                children:[
                    {
                        level_key:"lvl3",
                        level_value:"Desc1",
                        children:[
                            {
                                level_key:"lvl4",
                                level_value:"Check1",
                                children:[]
                            },
                            {
                                level_key:"lvl4",
                                level_value:"Check2",
                                children:[]
                            }
                        ]
                    }
                ]
            }
        ]
    },
    {
        level_key:"lvl1",
        level_value:"Code2",
        children:[
            {
                level_key:"lvl2",
                level_value:"Type2",
                children:[
                    {
                        level_key:"lvl3",
                        level_value:"Desc2",
                        children:[
                            {
                                level_key:"lvl4",
                                level_value:"Check1",
                                children:[]
                            }
                        ]
                    }
                ]
            }
        ]
    }
]

Here in eg. i have taken till lvl4 but any number of levels could be there like lvl5, lvl6....

I have tried a approach but i feel that is very complex and not scalable.

CodePudding user response：

You could take obbjects with level_value as key and take the arrays as result.

const
    flat = [{ lvl1:"Code1", lvl2:"Type1", lvl3:"Desc1", lvl4:"Check1" }, { lvl1:"Code1", lvl2:"Type1", lvl3:"Desc1", lvl4:"Check2" }, { lvl1:"Code2", lvl2:"Type2", lvl3:"Desc2", lvl4:"Check1" }],
    tree = flat.reduce((r, o) => {
        let temp = r,
            i = 1,
            level_key = `lvl${i}`,
            level_value = o[level_key];
        
        do {
            if (!temp[level_value]) {
                temp[level_value] = { _: [] };
                temp._.push({ level_key, level_value, children: temp[level_value]._ });
            }
            temp = temp[level_value];
            level_key = `lvl${  i}`;
            level_value = o[level_key];
        } while (level_value)
        return r;
    }, { _: [] })._;
    
    
console.log(tree);

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CodePudding user response：

I have tried this:

let output=[]

input.forEach(ele=>{
    let flag=1;
    output.forEach(outele=>{
        if(ele.lvl1==outele.level_value){
            flag=0;
        }
    })
    if(flag==1){
        let obj={level_key:"lvl1",level_value:ele.lvl1,children:[]};
        output.push(obj);
    }
})

input.forEach(ele=>{
    output.forEach(outele=>{
        let flag=1;
        if(ele.lvl1==outele.level_value){
            outele.children.forEach(outele2=>{
                if(ele.lvl2==outele2.level_value){
                    flag=0;
                }
            })
            if(flag==1){
                let obj={level_key:"lvl2",level_value:ele.lvl2,children:[]};
                outele.children.push(obj);
            }
        }
    })
    
})

input.forEach(ele=>{
    output.forEach(outele=>{
        outele.children.forEach(outele2=>{
            if(ele.lvl1==outele.level_value && ele.lvl2==outele2.level_value){    
                let flag=1;
                outele2.children.forEach(outele3=>{
                    if(ele.lvl3==outele3.level_value){
                        flag=0;
                    }
                })
                if(flag==1){
                    let obj={level_key:"lvl3",level_value:ele.lvl3,children:[]};
                    outele2.children.push(obj);
                }
            }
        })
    })
})

input.forEach(ele=>{
    output.forEach(outele=>{
        outele.children.forEach(outele2=>{
            outele2.children.forEach(outele3=>{
                if(ele.lvl1==outele.level_value && ele.lvl2==outele2.level_value && ele.lvl3==outele3.level_value){      
                    let flag=1;
                    outele3.children.forEach(outele4=>{
                        if(ele.lvl4==outele4.level_value){
                            flag=0;
                        }
                    })
                    if(flag==1){
                        let obj={level_key:"lvl4",level_value:ele.lvl4,children:[]};
                        outele3.children.push(obj);
                    }
                }
            })
        })
    })
})