Flutter:显示嵌套JSON数据中的指定行

Question

我有未来的建设者与未来的列表像这样，我想查看数据与空预测对象:

[
{
"id": 1,
"home": "Turkey",
"away": "Italy",
"h_goals": 0,
"a_goals": 0,
"date": "2021-02-06",
"time": "22:00",
"predect": [
{
"id": 3,
"user_id": 10,
"match_id": 1,
"h_predect": 1,
"a_predect": 1,
"player_id": 1,
"point": 0,
"username": "sar"
}
]
},
{
"id": 2,
"home": "Denmark",
"away": "Finland",
"h_goals": 0,
"a_goals": 0,
"date": "2021-06-12",
"time": "19:00",
"predect": []
},
]

我想显示有空预测的匹配细节，我有这个小部件，但不工作:

return FutureBuilder(
future: mathesProv.matchsWithUserPredects(username, token),
builder: (context, snapshot) {
if (snapshot.hasData) {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
var item = snapshot.data[index];
if (item.predect == null) {
return Text('${item.home}');
} else {
return Container(
child: Text('$index'),
);
}
});
} else {
return Text('loading');
}
});

如何查看具有空预测列表的行?

Answer 1

您忘记添加长度= 0的检查

return FutureBuilder(
future: mathesProv.matchsWithUserPredects(username, token),
builder: (context, snapshot) {
if (snapshot.hasData) {
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
var item = snapshot.data[index];
if ((item.predect == null)||(item.predect.length==0)) {
return Text('${item.home}');
} else {
return Container(
child: Text('$index'),
);
}
});
} else {
return Text('loading');
}
});