具有键值的 JSON 对象的数组格式

Question

I have an array with below format, I am trying to remove duplicate keys and merge it to one. Please let me know how to achieve this.

[
  {"tablename":"table1","tablecolumns":"yes"},
  {"tablename":"table1","columnname":"column1"},
  {"tablename":"table1","columnname":"col2"},
  {"tablename":"table2","tablecolumns":"yes"},
  {"tablename":"table2","columnname":"column3"},
  {"tablename":"table2","columnname":"col4"}
]

expected format:

[
    {"tablename":"table1","tablecolumns":"yes","columnname":"column1","columnname":"col2"},
    {"tablename":"table2","tablecolumns":"yes","columnname":"column3","columnname":"col4"}
]

Answer 1

You can use reduce method:

const result = arr.reduce((a, {tablename, tablecolumns, columnname}) => {
  a[tablename] = a[tablename] || {tablename, tablecolumns, columnnames: []};
  if (columnname)
    a[tablename].columnnames.push(columnname);
  return a;
},{})

An example:

 let arr = [ { "tablename": "table1", "tablecolumns": "yes" }, { "tablename": "table1", "columnname": "column1" }, { "tablename": "table1", "columnname": "col2" }, { "tablename": "table2", "tablecolumns": "yes" }, { "tablename": "table2", "columnname": "column3" }, { "tablename": "table2", "columnname": "col4" } ]; const result = arr.reduce((a, {tablename, tablecolumns, columnname}) => { a[tablename] = a[tablename] || {tablename, tablecolumns, columnnames: []}; if (columnname) a[tablename].columnnames.push(columnname); return a; },{}) console.log(Object.values(result));

UPDATE:

If you have an additional tag datatype , then you can use the following code snippet:

 let arr = [ {"tablename":"table1","tablecolumns":"yes"}, {"tablename":"table1","columnname":"col1","datatype":"Alphabetic"}, {"tablename":"table2","tablecolumns":"yes"}, {"tablename":"table2","columnname":"tabl2_colu","datatype":null}, {"tablename":"table2","columnname":"tab2_col2","datatype":"Numeric"} ]; const result = arr.reduce((a, {tablename, tablecolumns, columnname, datatype}) => { a[tablename] = a[tablename] || {tablename, tablecolumns, columns: []}; if (columnname) a[tablename].columns.push({columnname, datatype}); return a; },{}) console.log(Object.values(result));

Answer 2

So I have mentioned in my comment below your question you can't have the same property name for an object as you expect - columnname .

Instead I suggest to have a different structure and store the column names in an array.

Like the following:

 const data = [ {"tablename":"table1","tablecolumns":"yes"}, {"tablename":"table1","columnname":"column1"}, {"tablename":"table1","columnname":"col2"}, {"tablename":"table2","tablecolumns":"yes"}, {"tablename":"table2","columnname":"column3"}, {"tablename":"table2","columnname":"col4"} ]; const result = data.reduce((a,c) => { const foundelem = a.find(e => e.tablename === c.tablename); if (foundelem) { foundelem.columnnames.push(c.columnname); } else { a.push({ tablename: c.tablename, tablecolumns: c.tablecolumns, columnnames: [] }); } return a; }, []); console.log(result);

I hope that helps!