java - Android Sugar ORM - 带列表的类模型

Question

我正在尝试将我的 android 项目与 SQLite 数据库集成，但我对这个数据库很陌生，所以我使用 Sugar ORM帮助我处理项目的数据库方面的问题。

问题是我的类模型之一包含列表:

public class MyObject extends SugarRecord implements Parcelable {

    public String myString;
    public List<String> myStringList;

    public MyObject () { }

    private MyObject (Parcel in) {
        myString= in.readString();
        myStringList= new ArrayList<>(); 
        in.readList(myStringList, String.class.getClassLoader());
    }

    public static final Creator<MyObject> CREATOR = new Creator<MyObject>() {
        public MyObjectcreateFromParcel(Parcel in) { return new MyObject(in); }
        public MyObject[] newArray(int size) { return new MyObject[size]; }
    };

    @Override
    public int describeContents() { return 0; }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(myString);
        dest.writeList(myStringList);
    }
}

当我尝试读取我的数据库时出现此错误:

Class cannot be read from Sqlite3 database. Please check the type of field myStringList(java.util.List)

我想在我的数据库中创建列的方式不支持列表。有什么解决方法吗？我应该如何处理这个问题？

Answer 1

SugarORM 不支持存储Array 或Lists 您可以使用一些策略来支持这一点，但需要您引入依赖项。

基本思想是将数据列表转换为JSON，然后将其存储为String

import com.google.gson.Gson;

public class MyObject extends SugarRecord implements Parcelable {
    public String myString;
    @Ignore //Sugar will ignore this field. 
    private List<String> myStringList;  //Change to private (accessed via getter/setter method)
    private String myStringListStore; //to store the list in JSON format. 

    public MyObject () { }

    private MyObject (Parcel in) {
        this.myString= in.readString();
        this.myStringList= new ArrayList<>(); 
        in.readList(myStringList, String.class.getClassLoader());
    }

    public static final Creator<MyObject> CREATOR = new Creator<MyObject>(){
        public MyObjectcreateFromParcel(Parcel in) { return new MyObject(in); }
        public MyObject[] newArray(int size) { return new MyObject[size]; }
    };

    public List<String> getMyStringList(){
        //Convert from JSON string to List
       myStringList =  new Gson().fromJson(this.myStringListStore,new TypeToken<List<String>>(){}.getType());
       return myStringList;
    }

    public setMyStringList(List<String> stringList){
        this.myStringList = stringList;
    }

    //Override save to ensure the list is converted into JSON before saving. 
    @Override
    public long save(){
        this.myStringListStore = new Gson().toJson(stringList); 
        return super.save();
    }

    @Override
    public int describeContents() { return 0; }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeString(myString);
        dest.writeList(getMyStringList());
    }
}