英文:
GSON skip class if object in class is empty/null
问题
我正在为我的 Discord 机器人编写权限系统。
我面临的问题是 JSON 数据中出现了很多“空”对象。
我想要跳过这样的对象：
"userId": {
"userName": "RandomDiscord Name",
"permissions": []
},
但要保留这样的对象：
"userId": {
"userName": "RandomDiscord Name",
"permissions": [
"some.permission.string",
"some.permission.string2",
"some.permission.string3"
]
},
我尝试使用 ExclusionStrategy => shouldSkipClass(Class<?> aClass)，在该方法中检查该类的内容。像这样：
@Override
public boolean shouldSkipClass(Class<?> aClass) {
if(aClass instanceof PermissionUser){
PermissionUser user = (PermissionUser) aClass;
return user.getPermissions().isEmpty();
}
return false;
}
但这行不通，因为我只能获得类的类型，无法进行强制转换。
有人可以指导我正确的方向吗？
（请友善对待我，我白天是医护人员，编程只是业余爱好）
英文:
I'm currently writing a permission system for my discord bot.
The problem that I'm facing is that the JSON gets quite full of "empty" objects.
I want to skip objects like these
"userId": {
"userName": "RandomDiscord Name",
"permissions": []
},
But keep objects like these
"userId": {
"userName": "RandomDiscord Name",
"permissions": [
"some.permission.string",
"some.permission.string2",
"some.permission.string3",
]
},
I try to get a ExclusionStrategy => shouldSkipClass(Class<?> aClass) where I can check for the content for the that said class. Like
@Override
public boolean shouldSkipClass(Class<?> aClass) {
if(aClass instanceof PermissionUser){
PermissionUser user = (PermissionUser) aClass;
return user.getPermissions().isEmpty();
}
return false;
}
But this won't work since I won't get the instance, only type of class, so I can't cast it.
Can anyone point me in the right direction?
(Be nice to me, paramedic by daytime, programming only as a hobby)
答案1
得分: 1
Okay, I found a way to do this.
Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation()
.registerTypeAdapter(PermissionUser.class, new PermissionUserAdapter())
.registerTypeAdapter(PermissionGroup.class, new PermissionGroupAdapter())
.setPrettyPrinting().create();
The adapter looks like this.
public class PermissionUserAdapter implements JsonSerializer<PermissionUser> {
@Override
public JsonElement serialize(PermissionUser src, Type typeOfSrc, JsonSerializationContext context) {
if (!src.getPermissions().isEmpty() && src.getPermissions() != null) {
Gson gson = new GsonBuilder().setPrettyPrinting().excludeFieldsWithoutExposeAnnotation().create();
return gson.toJsonTree(src);
}
return null;
}
}
Quite simple once I got the right direction. If anybody has a better idea, feel free to correct me.
英文:
Okay, I found a way todo this.
Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation()
.registerTypeAdapter(PermissionUser.class, new PermissionUserAdapter())
.registerTypeAdapter(PermissionGroup.class, new PermissionGroupAdapter())
.setPrettyPrinting().create();
The adapter looks like this.
public class PermissionUserAdapter implements JsonSerializer<PermissionUser> {
@Override
public JsonElement serialize(PermissionUser src, Type typeOfSrc, JsonSerializationContext context) {
if(!src.getPermissions().isEmpty() && src.getPermissions() != null){
Gson gson = new GsonBuilder().setPrettyPrinting().excludeFieldsWithoutExposeAnnotation().create();
return gson.toJsonTree(src);
}
return null;
}
}
Quite simple once I got the right direction. If anybody has a better Idea, feel free to correct me.
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