所有人！我使用react，希望json输出count“employees”，如下所示：在这里输入图像描述

[
{
    "id": 1,
    "departmentName": "Development",
    "employees": [
        {
            "id": 1,
            "name": "Max",
            "departmentId": 1,
            "salary": 20000.0,
            "city": "berlin",
            "street": "First st.",
            "bankName": "bank",
            "cardNumber": "de12345678912"
        },
        {
            "id": 2,
            "name": "Sam",
            "departmentId": 1,
            "salary": 20000.0,
            "city": "new york",
            "street": "Second st.",
            "bankName": null,
            "cardNumber": null
        }
    ]
},

对于呈现json，我使用datatable

<DataTable value={this.state.departments} paginator={true} rows="25" selectionMode="single"
                           selection={this.state.selectedDepartment}
                           onSelectionChange={e => this.setState({selectedDepartment: e.value})}>
                    <Column field="id" header="ID"/>
                    <Column field="departmentName" header="Department"/>
                </DataTable>

如何为count employees添加字段？