如何使用built_value和built_collection来为以下JSON响应编写模型。
"totals": {
"2019-06-09": {
"sales": "6505.00",
"orders": 19,
"items": 55,
"tax": "0.00",
"shipping": "400.00",
"discount": "0.00",
"customers": 12
},
"2019-06-10": {
"sales": "13335.00",
"orders": 29,
"items": 79,
"tax": "0.00",
"shipping": "390.00",
"discount": "0.00",
"customers": 11
},
"2019-06-11": {
"sales": "6395.00",
"orders": 20,
"items": 45,
"tax": "0.00",
"shipping": "250.00",
"discount": "0.00",
"customers": 10
},
"2019-06-12": {
"sales": "8125.00",
"orders": 17,
"items": 59,
"tax": "0.00",
"shipping": "340.00",
"discount": "0.00",
"customers": 9
},
"2019-06-13": {
"sales": "12205.00",
"orders": 30,
"items": 86,
"tax": "0.00",
"shipping": "370.00",
"discount": "0.00",
"customers": 18
},
"2019-06-14": {
"sales": "4970.00",
"orders": 17,
"items": 36,
"tax": "0.00",
"shipping": "310.00",
"discount": "0.00",
"customers": 16
},
"2019-06-15": {
"sales": "0.00",
"orders": 0,
"items": 0,
"tax": "0.00",
"shipping": "0.00",
"discount": "0.00",
"customers": 0
}
}