how to convert an array of objects into single object

Question

I am Getting response data from node.js api in below json format where i am joining two tables with inner join. table 1 is having columns: id, name, description, layername and table 2 is having columns attrName, datatype. one to many relationship between two tables.

   [
{
    "id": 788,
    "name": "ABC",
    "description": "abc",
    "layername": "abclayer",
    "file_type": "Parquet",
    "attrname": "Id",
    "datatype": "integer",
    "length": 20
},
{
    "id": 788,
    "name": "ABC",
    "description": "abc",
    "layername": "abclayer",
    "file_type": "Parquet",
    "attrname": "Name",
    "datatype": "varchar",
    "length": 40
    
}

]

But I need response data in below format. What is the correct way to get data by writing query for both tables.

{
"name": "ABC",
"description": "abc",
"fieldDetails": [
    {
        "attributeName": "Id",
        "datatype": "integer",
        "length": 20
    },   {
        "attributeName": "Name",
        "datatype": "varchar",
        "length": 40
    },    
],
"layername": "abclayer",
"file_type": "Parquet"
}

node.js api code.

    getDataById = (dP, id) => {
    return new Promise((resolve, reject) => {
        const userDBName = dP.DatabaseName + ".\"" + dP.SchamaName + "\"";
        const dimTable = dP.DimensionListTable;
        const dimConfigTable = dP.DimensionConfigTable;

        let query = "Select dim.id, dim.name, dim.description, dim.layername, dim.file_type, dimConfig.attributename, " +
        "dimConfig.datatype, dimConfig.length, dimConfig.primarykey, dimConfig.partitionby, dimConfig.start_index " +
        "From " + userDBName + "." + dimTable + " dim INNER JOIN " + userDBName + "." + dimConfigTable + " dimConfig " +
        "ON dim.id = dimConfig.dim_id  and dim.Id = '" + id + "'";

        console.log("newwwwQueryyy " + query)
        mysql.executeQuery(query).then(result => {
            console.log("schemaData" + JSON.stringify(result) + "count" + result.length);
            resolve({ "schemaData": result, "count": result.length });

        }).catch(err => {
            console.log(resolve({ "schemaData": [], "count": 0 }));
        })
    });
}

Answer 1

You can use reduce .

Stackblitz code

const data =   [
    {
        "id": 788,
        "name": "ABC",
        "description": "abc",
        "layername": "abclayer",
        "file_type": "Parquet",
        "attrname": "Id",
        "datatype": "integer",
        "length": 20
    },
    {
        "id": 788,
        "name": "ABC",
        "description": "abc",
        "layername": "abclayer",
        "file_type": "Parquet",
        "attrname": "Name",
        "datatype": "varchar",
        "length": 40
        
    }
]  

const obj = data.reduce((acc, curr) => {
    return {
        ...acc,
        fieldDetails: [...acc.fieldDetails, {
            attributeName: curr.attrname,
            datatype: curr.datatype,
            length: curr.length
        }]
    }
}, {
    name: data[0].name,
    description: data[0].description,
    layername: data[0].layername,
    file_type: data[0].file_type,
    fieldDetails: []
});

console.log(obj);

Answer 2

 const data = [ { "id": 788, "name": "ABC", "description": "abc", "layername": "abclayer", "file_type": "Parquet", "attrname": "Id", "datatype": "integer", "length": 20 }, { "id": 788, "name": "ABC", "description": "abc", "layername": "abclayer", "file_type": "Parquet", "attrname": "Name", "datatype": "varchar", "length": 40 } ] let fieldDetails = []; data.forEach(element => { fieldDetails.push({ "attributeName": element['attrname'], "datatype": element['datatype'], "length": element['length'] }) }); const newdata = data.map(x => { return { "name": x.name, "description": x.description, "fieldDetails": fieldDetails, "layername": x.layername, "file_type": x.file_type } }) console.log(newdata[0])