Flutter 颤振：按日期读取和合并firestore数据

我正在寻找一种方法，按日期合并从CloudFireStore读取的数据。我的目标是从CloudFireStore中读取所有文档，然后将某个日期的所有文档放在一个

扩展文件下。i、 e.每个日期一个
expansionfile
，每个
expansionfile
可能包含许多单独的文档，具体取决于当天上载的文档数量

我从Cloud Firestore读取数据没有问题，但我很难弄清楚一旦掌握了信息，如何按日期组织和合并文档。请记住，将有多个不同的日期，每个日期都有不同数量的文档

如下图所示，我目前有三个日期相同的文档，因此在应用程序中创建它们时有三个不同的
扩展文件。我希望将这三个文件转换为一个
expansionfile


我目前正在使用以下软件包按日期从Cloud Firestore读取数据：

//检索过去完成的所有订单的firebase数据
流\u loadOrderHistory（）异步*{
试一试{
_orderSubscription？.cancel（）；
var orderHistory=Firestore.instance
.收款（“订单”）
.orderBy（'date'，降序：true）；
_orderSubscription=orderHistory.snapshots（）。侦听(
（活动）{
如果（event.documents.length>0）{
添加（OrderHistoryUpdate）(
文档：event.documents，
));
}否则{
打印（“无需加载订单”）；
添加（NoOrderHistory（））；
}
},
);
}捕获（e）{
打印（“跟踪状态错误，$e”）；
添加（ErrorOrderHistory（））；
}  
}
对于那些好奇的人来说，这是我解决问题的方法。它可能有点冗长，因此任何缩短/改进它的建议仍然非常感谢：

                  //Make sure that there are documents within firebase
                  if (state.orderHistoryDocuments.length != 0) {
                    //Adding the first document manually so that
                    //the forloop section has something to compare dates
                    //This listForEachDate is for storing a collection
                    //of all documents of one date
                    listForEachDate = [state.orderHistoryDocuments[0].data];
                    //listOfDateLists is a list of all listForEachDate
                    //This gives us a list of lists with the documents
                    //separated by date i.e.
                    //[[date1, date1], [date2], [date3, date3, date3], etc]
                    listOfDateLists = [];

                    //i = 1 because index 0 already added above
                    for (int i = 1;
                        i < state.orderHistoryDocuments.length;
                        i++) {
                      //If the current index's date matches that of the previous
                      //index's date, then add it to the listForEachDate
                      if (state.orderHistoryDocuments[i]
                              .data["dateCreated"] ==
                          state.orderHistoryDocuments[i - 1]
                              .data["dateCreated"]) {
                        listForEachDate
                            .add(state.orderHistoryDocuments[i].data);
                        //If [index]date does not match [index - 1]date
                        //Then add the current listForEachDate to the
                        //listOfDateLists i.e. add sublist to list of lists
                      } else {
                        listOfDateLists.add(listForEachDate);
                        //Clear the listForEachDate so that we can create
                        //a new clean list of new dates
                        listForEachDate = [];
                        //Add the new date to the listForEachDate
                        //so that the process can start again
                        listForEachDate
                            .add(state.orderHistoryDocuments[i].data);
                      }
                    }
                    //Once the document has been iterated through,
                    //Add to the big list.
                    listOfDateLists.add(listForEachDate);
                  }

//确保firebase中有文档
if（state.orderHistoryDocuments.length！=0）{
//手动添加第一个文档，以便
//forloop部分可以比较日期
//此listForEachDate用于存储集合
//一个日期的所有文件的
listForEachDate=[state.orderHistoryDocuments[0].data]；
//listOfDateLists是所有listForEachDate的列表
//这为我们提供了一个包含文档的列表
//按日期分开，即。
//[[日期1，日期1]，[日期2]，[日期3，日期3，日期3]等]
listOfDateLists=[]；
//i=1，因为上面已经添加了索引0
对于（int i=1；
i

                  //Make sure that there are documents within firebase
                  if (state.orderHistoryDocuments.length != 0) {
                    //Adding the first document manually so that
                    //the forloop section has something to compare dates
                    //This listForEachDate is for storing a collection
                    //of all documents of one date
                    listForEachDate = [state.orderHistoryDocuments[0].data];
                    //listOfDateLists is a list of all listForEachDate
                    //This gives us a list of lists with the documents
                    //separated by date i.e.
                    //[[date1, date1], [date2], [date3, date3, date3], etc]
                    listOfDateLists = [];

                    //i = 1 because index 0 already added above
                    for (int i = 1;
                        i < state.orderHistoryDocuments.length;
                        i++) {
                      //If the current index's date matches that of the previous
                      //index's date, then add it to the listForEachDate
                      if (state.orderHistoryDocuments[i]
                              .data["dateCreated"] ==
                          state.orderHistoryDocuments[i - 1]
                              .data["dateCreated"]) {
                        listForEachDate
                            .add(state.orderHistoryDocuments[i].data);
                        //If [index]date does not match [index - 1]date
                        //Then add the current listForEachDate to the
                        //listOfDateLists i.e. add sublist to list of lists
                      } else {
                        listOfDateLists.add(listForEachDate);
                        //Clear the listForEachDate so that we can create
                        //a new clean list of new dates
                        listForEachDate = [];
                        //Add the new date to the listForEachDate
                        //so that the process can start again
                        listForEachDate
                            .add(state.orderHistoryDocuments[i].data);
                      }
                    }
                    //Once the document has been iterated through,
                    //Add to the big list.
                    listOfDateLists.add(listForEachDate);
                  }