如何从Firestore获取DocumentReference字段?

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英文:

How do I get a DocumentReference field from Firestore?

问题

以下是翻译好的内容:

我正在尝试从 Google Firestore 检索一个对象,这是该对象:

Firestore对象

由于我添加了属性 "soat",我在使用以下类对对象进行反序列化时遇到错误:

@Data
public class Car {
    private String plate;
    private String model;
    private long km;
    private boolean available;
    private DocumentReference soat;   
}

以及用于从 Firestore 检索所有 Car 对象的代码:

@Override
public List<Car> findAll() {
    List<Car> empList = new ArrayList<Car>();
    CollectionReference car = fb.getFirestore().collection("Cars");
    ApiFuture<QuerySnapshot> querySnapshot = car.get();
    try {
        for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {
            Car emp = doc.toObject(Car.class);
            empList.add(emp);
        }
    } catch (Exception e) {
         e.printStackTrace();
    }
    return empList;
}

由于我添加了属性 "soat",当请求数据时我遇到了这个错误:

ERROR 7544 --- [nio-8080-exec-7] s.e.ErrorMvcAutoConfiguration$StaticView : 无法为请求 [请求路由] 和异常 [无法写入 JSON:无限递归 (StackOverflowError);嵌套异常是 com.fasterxml.jackson.databind.JsonMappingException:无限递归 (StackOverflowError) (通过引用链:com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]...
->com.google.cloud.firestore.FirestoreOptions["modulus"]]) 渲染错误页面,因为响应已经被提交。因此,

以前我无法正确进行请求,因此我在我的 application.properties 中添加了以下内容:

spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false

编辑:刚刚尝试了这个方法,仍然遇到相同的错误

@Override
public List<Car> findAll() {
    List<Car> empList = new ArrayList<Car>();
    CollectionReference car = fb.getFirestore().collection("Cars");
    ApiFuture<QuerySnapshot> querySnapshot = car.get();
    try {
        for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {
           
             String plate = doc.getData().get("plate").toString();
             String model = doc.getData().get("model").toString();
             long km = Long.parseLong(doc.getData().get("km").toString());
             boolean available = Boolean.parseBoolean(doc.getData().get("available").toString());
             DocumentReference soat = (DocumentReference) doc.getData().get("soat");

            Car emp = new Car();
            emp.setAvailable(available);
            emp.setKm(km);
            emp.setModel(model);
            emp.setPlate(plate);
            emp.setSoat(soat);

            empList.add(emp);
        }
    } catch (Exception e) {
         e.printStackTrace();
    }
    return empList;
}

-------编辑--------

我已将以下内容添加到我的 application.properties 文件中

spring.jackson.serialization.fail-on-self-references=false

现在我从 Firestore 调用中获得了以下内容:

[{"plate":"HEO628","model":"2014","km":75000,"available":true,"soat":{"path":"SOATS/HEO628","parent":{"parent":null,"id":"SOATS","path":"SOATS","firestore":{"firestore":{"firestore":{"firestore":{"firestore":{"firestore":{"firestore":{"firestore":{"firestore":...
英文:

Im trying to retrieve an object from a google Firestore, this is the object:

Firestore object

Since i added the atribute soat im getting erros im using this class to deserialize the object:

@Data
public class Car {
    private String plate;
    private String model;
    private long km;
    private boolean available;
    private DocumentReference soat;   
}

And this code to retrieve the all the Car objects from the Firestore

     @Override
    public List&lt;Car&gt; findAll() {
        List&lt;Car&gt; empList = new ArrayList&lt;Car&gt;();
        CollectionReference car = fb.getFirestore().collection(&quot;Cars&quot;);
        ApiFuture&lt;QuerySnapshot&gt; querySnapshot = car.get();
        try {
            for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {
                Car emp = doc.toObject(Car.class);
                empList.add(emp);
            }
        } catch (Exception e) {
             e.printStackTrace();
        }
		return empList;
    }

Since i added the property soat im getting this error whe requesting the data

> ERROR 7544 --- [nio-8080-exec-7] s.e.ErrorMvcAutoConfiguration$StaticView : Cannot render error page for request [request route] and exception [Could not write JSON: Infinite recursion (StackOverflowError); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain: com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]->com.google.cloud.firestore.FirestoreOptions["service"]->com.google.cloud.firestore.FirestoreImpl["options"]...
> ->com.google.cloud.firestore.FirestoreOptions["credentia
["modulus"])] as the response has already been committed. As a result,

Previously i couldnt make the request properly so i added this to my application.properties

spring.jackson.serialization.FAIL_ON_EMPTY_BEANS=false

Edit: just tried this aproach and still getting same error

    @Override
    public List&lt;Car&gt; findAll() {
        List&lt;Car&gt; empList = new ArrayList&lt;Car&gt;();
        CollectionReference car = fb.getFirestore().collection(&quot;Cars&quot;);
        ApiFuture&lt;QuerySnapshot&gt; querySnapshot = car.get();
        try {
            for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {
               
                 String plate=doc.getData().get(&quot;plate&quot;).toString();
                 String model=doc.getData().get(&quot;model&quot;).toString();
                 long km=Long.parseLong(doc.getData().get(&quot;km&quot;).toString());
                 boolean available=Boolean.parseBoolean(doc.getData().get(&quot;available&quot;).toString());
                 DocumentReference soat=(DocumentReference)doc.getData().get(&quot;soat&quot;);

                Car emp = new Car();
                emp.setAvailable(available);
                emp.setKm(km);
                emp.setModel(model);
                emp.setPlate(plate);
                emp.setSoat(soat);

                empList.add(emp);
            }
        } catch (Exception e) {
             e.printStackTrace();
        }
		return empList;
    }

-------EDIT--------<br>
I have aded this to my application.properties

spring.jackson.serialization.fail-on-self-references=false

And now i get this from the Firestore call

[{&quot;plate&quot;:&quot;HEO628&quot;,&quot;model&quot;:&quot;2014&quot;,&quot;km&quot;:75000,&quot;available&quot;:true,&quot;soat&quot;:{&quot;path&quot;:&quot;SOATS/HEO628&quot;,&quot;parent&quot;:{&quot;parent&quot;:null,&quot;id&quot;:&quot;SOATS&quot;,&quot;path&quot;:&quot;SOATS&quot;,&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:{&quot;firestore&quot;:

答案1

得分: 1

基本上,您需要创建一个类来反序列化您的 DatabaseReference,在这种情况下,类名将为SOAT,并使用它来存储对数据库的引用。

@Data
public class Car {
    private String plate;
    private String model;
    private long km;
    private boolean available;
    private SOAT soat;  
    private Insurance insurance;
    private Techno techno;
}

然后在从 FireBase 检索信息时,您需要进行以下请求,以便指定要映射的对象类型。

public List<Car> findAll() {
    List<Car> empList = new ArrayList<Car>();
    CollectionReference car = fb.getFirestore().collection("Cars");
    ApiFuture<QuerySnapshot> querySnapshot = car.get();
    try {
        for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {

            String plate = doc.getData().get("plate").toString();
            String model = doc.getData().get("model").toString();
            long km = Long.parseLong(doc.getData().get("km").toString());
            boolean available = Boolean.parseBoolean(doc.getData().get("available").toString());
            DocumentSnapshot soatref = fb.getFirestore().collection("SOATS").document(plate).get().get();
            DocumentSnapshot technoref = fb.getFirestore().collection("Technos").document(plate).get().get();
            DocumentSnapshot insuranceref = fb.getFirestore().collection("Insurances").document(plate).get().get();
            SOAT soat = soatref.toObject(SOAT.class);
            Techno techno = technoref.toObject(Techno.class);
            Insurance insurance = insuranceref.toObject(Insurance.class);

            Car emp = new Car();
            emp.setAvailable(available);
            emp.setKm(km);
            emp.setModel(model);
            emp.setPlate(plate);
            emp.setSoat(soat);
            emp.setInsurance(insurance);
            emp.setTechno(techno);

            empList.add(emp);
        }
    } catch (Exception e) {

    }
    return empList;
}

然后在调用您的 API 时,您应该获得一个正确的对象引用,如下所示。

{
    "plate": "HEO628",
    "model": "2014",
    "km": 75000,
    "available": true,
    "soat": {
        "expeditionDate": "2020-09-29T06:12:12.000+00:00",
        "carPlate": "HEO628"
    },
    "insurance": {
        "expeditionDate": "2020-10-01T11:12:12.000+00:00",
        "carPlate": "HEO628"
    },
    "techno": {
        "expeditionDate": "2020-09-08T17:00:00.000+00:00",
        "carPlate": "HEO628"
    }
}
英文:

Basically you have to create a class to deserialice your DatabaseReference, in this case the class name would be SOAT and use it to sotre your reference to the database.

@Data
public class Car {
private String plate;
private String model;
private long km;
private boolean available;
private SOAT soat;  
private Insurance insurance;
private Techno techno;
}

Then when retrieving the information from FireBase you have to make the following requests in order to specify the kind of object your are going to map.

public List&lt;Car&gt; findAll() {
List&lt;Car&gt; empList = new ArrayList&lt;Car&gt;();
CollectionReference car = fb.getFirestore().collection(&quot;Cars&quot;);
ApiFuture&lt;QuerySnapshot&gt; querySnapshot = car.get();
try {
for (DocumentSnapshot doc : querySnapshot.get().getDocuments()) {
String plate = doc.getData().get(&quot;plate&quot;).toString();
String model = doc.getData().get(&quot;model&quot;).toString();
long km = Long.parseLong(doc.getData().get(&quot;km&quot;).toString());
boolean available = Boolean.parseBoolean(doc.getData().get(&quot;available&quot;).toString());
DocumentSnapshot soatref = fb.getFirestore().collection(&quot;SOATS&quot;).document(plate).get().get();
DocumentSnapshot technoref = fb.getFirestore().collection(&quot;Technos&quot;).document(plate).get().get();
DocumentSnapshot insuranceref = fb.getFirestore().collection(&quot;Insurances&quot;).document(plate).get().get();
SOAT soat = soatref.toObject(SOAT.class);
Techno techno = technoref.toObject(Techno.class);
Insurance insurance = insuranceref.toObject(Insurance.class);
Car emp = new Car();
emp.setAvailable(available);
emp.setKm(km);
emp.setModel(model);
emp.setPlate(plate);
emp.setSoat(soat);
emp.setInsurance(insurance);
emp.setTechno(techno);
empList.add(emp);
}
} catch (Exception e) {
}
return empList;
}

An then whe calling your API you shold get a proper reference to the Object like this.

{
&quot;plate&quot;: &quot;HEO628&quot;,
&quot;model&quot;: &quot;2014&quot;,
&quot;km&quot;: 75000,
&quot;available&quot;: true,
&quot;soat&quot;: {
&quot;expeditionDate&quot;: &quot;2020-09-29T06:12:12.000+00:00&quot;,
&quot;carPlate&quot;: &quot;HEO628&quot;
},
&quot;insurance&quot;: {
&quot;expeditionDate&quot;: &quot;2020-10-01T11:12:12.000+00:00&quot;,
&quot;carPlate&quot;: &quot;HEO628&quot;
},
&quot;techno&quot;: {
&quot;expeditionDate&quot;: &quot;2020-09-08T17:00:00.000+00:00&quot;,
&quot;carPlate&quot;: &quot;HEO628&quot;
}
}

huangapple
  • 本文由 发表于 2020年10月5日 03:11:45
  • 转载请务必保留本文链接:https://go.coder-hub.com/64198805.html
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