具有键值的 JSON 对象的数组格式

Question

我有一个格式如下的数组，我正在尝试删除重复的键并将其合并为一个。请告诉我如何实现这一目标。

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

预期格式：

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

Answer 1

所以我在下面的评论中提到了您的问题，您不能像您期望的那样为对象使用相同的属性名称 - columnname。

我建议使用不同的结构并将列名存储在数组中。

如下：

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);

希望对你有帮助！

Answer 2

你可以使用reduce方法：

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

一个例子：

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));

更新：

如果你有一个额外的标签datatype，那么你可以使用下面的代码sn -p：

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));