android - 无法检查从Cloud Firestore数据库检索的文档是否具有数据

Question

我正在从Firestore检索数据，但似乎无法使我的代码正常工作。当它在我给它的集合中找不到数据时，我希望它显示某些东西。 ................................................... ................................................... ..........
这是我的代码:

     StreamBuilder( 
                      stream: Firestore.instance.collection("payments").where('participants', arrayContains: userActive).snapshots(),
                      builder: (context, snapshot){


                        
                     

                      return Container ( child:ListView.builder(
                          shrinkWrap: true,
                        itemCount: snapshot.data.documents.length,
                        padding: EdgeInsets.all(0),
                        controller: ScrollController(keepScrollOffset: false),
                        itemBuilder: (context, index){

                           DocumentSnapshot documentSnapshot = snapshot.data.documents[index].data();

                          if(snapshot.data.documents.isEmpty){

                               print("No Data!!!");


                          }else{


                            print("Found Data!!!");
                          }

                     /*   if(documentSnapshot["receiver_name"] == userActive )  {         
                                                            

                                                              
                            return Container(
                            margin: EdgeInsets.symmetric(horizontal: 32,vertical: 5),
                            padding: EdgeInsets.all(16),
                            decoration: BoxDecoration(
                              color: Colors.white,
                              borderRadius: BorderRadius.all(Radius.circular(20))
                            ),
                            child: Row(
                              children: <Widget>[
                                Container(
                                  decoration: BoxDecoration(
                                      color: Colors.grey[100],
                                      borderRadius: BorderRadius.all(Radius.circular(18))
                                  ),
                                  child: Icon(Icons.attach_money, color: Colors.lightBlue[900],),
                                  padding: EdgeInsets.all(12),
                                ),

                                SizedBox(width: 16,),
                                Expanded(
                                  
                                  child: Column(


                                    crossAxisAlignment: CrossAxisAlignment.start,
                                    children: <Widget>[
                                      
                                    Text("Recieved", style: TextStyle(fontSize: 18, fontWeight: FontWeight.w700, color: Colors.grey[900]),) ,

                                    
                                   
                                      Text("" + documentSnapshot["currency_received"] + documentSnapshot["amount_received"], style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: Colors.grey[500]),),
                                   

                                   
                                     
                                                                      
                                   
                                    ],
                                  ),
                                ),

                                Column(
                                  crossAxisAlignment: CrossAxisAlignment.end,
                                  children: <Widget>[

                                    


                                    Text("+ " + documentSnapshot["currency_sent"] + documentSnapshot["amount_paid"].toString(), style: TextStyle(fontSize: 18, fontWeight: FontWeight.w700, color: Colors.lightGreen),),



                                
 Text(documentSnapshot["date"].toDate().toString(), style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: Colors.grey[500]),),                                
                                  ],
                                ),
                              ],
                            ),
                          );


                      } else if (documentSnapshot["sender_name"] == userActive){



                     return Container(
                            margin: EdgeInsets.symmetric(horizontal: 32,vertical: 5),
                            padding: EdgeInsets.all(16),
                            decoration: BoxDecoration(
                              color: Colors.white,
                              borderRadius: BorderRadius.all(Radius.circular(20))
                            ),
                            child: Row(
                              children: <Widget>[
                                Container(
                                  decoration: BoxDecoration(
                                      color: Colors.grey[100],
                                      borderRadius: BorderRadius.all(Radius.circular(18))
                                  ),
                                  child: Icon(Icons.attach_money, color: Colors.lightBlue[900],),
                                  padding: EdgeInsets.all(12),
                                ),

                                SizedBox(width: 16,),
                                Expanded(
                                  
                                  child: Column(


                                    crossAxisAlignment: CrossAxisAlignment.start,
                                    children: <Widget>[
                                      
                                    Text("Sent", style: TextStyle(fontSize: 18, fontWeight: FontWeight.w700, color: Colors.grey[900]),) ,

                                    
                                   
                                      Text("" +  documentSnapshot["currency_received"] + documentSnapshot["amount_received"], style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: Colors.grey[500]),),
                                   

                                   
                                     
                                                                      
                                   
                                    ],
                                  ),
                                ),

                                Column(
                                  crossAxisAlignment: CrossAxisAlignment.end,
                                  children: <Widget>[

                                    


                                    Text("- " + documentSnapshot["currency_sent"] + documentSnapshot["amount_paid"].toString(), style: TextStyle(fontSize: 18, fontWeight: FontWeight.w700, color: Colors.orange),),



                                
                                                 Text(documentSnapshot["date"].toDate().toString(), style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: Colors.grey[500]),),
                                
                                  ],
                                ),
                              ],
                            ),
                          );








                        
                 



                      }else{
                                    
                                        
                                        return Text("Nothng found ",style: TextStyle(fontSize: 15, fontWeight: FontWeight.w700, color: Colors.black));
                      }


*/
                                                            
                       
                        

                        },
                       )
                      );
                        
 }
 



  
   ),
                 

Answer 1

Firestore最近有一个新更新，您必须使用.data()检索值。
为了使您的代码正常工作，您必须对此进行更改:

DocumentSnapshot documentSnapshot = snapshot.data.docs[index]; //not working code

最后添加 .data():

DocumentSnapshot documentSnapshot = snapshot.data.documents[index].data(); //working code