Response.take(Class<T>, int) throws a NullPointerException if the query returns no results

[emmanuel-keller]

          I noticed that `Response.take(Class<T>, int)` throws a `NullPointerException` if the query returns no results instead of returning null or an empty instance. This makes error handling more difficult in cases where no matching entry exists.

Would it be possible to handle this case more gracefully by returning null or an empty object instead of throwing an exception?

Here is my stack trace when this issue occurs:

java.lang.NullPointerException: Object instance not found at com.surrealdb.Value.getObject(Native Method) at com.surrealdb.Value.getObject(Value.java:109) at com.surrealdb.ValueClassConverter.convert(ValueClassConverter.java:175) at com.surrealdb.Value.get(Value.java:212) at dev.massi.ayase.database.model.AyaseUser.lambda$findById$0(AyaseUser.java:74)

Originally posted by @massikhr in #106 (comment)

[massikhr]

I’m still experiencing the NullPointerException issue when using Response.take(Class<T>, int) If the query returns no results, it throws an exception instead of returning null or an empty instance.

Debugging steps:

• Query execution works, and Response.toString() shows a pointer, but take() still fails.
• Here’s my latest code:

`public static CompletableFuture findById(Long userId) {
return CompletableFuture.supplyAsync(() -> {
System.out.println("1: params map");
final HashMap<String, Long> map = new HashMap<>();
map.put("$userId", userId);

    System.out.println("2: execute query");
    Response response = Ayase.surreal().queryBind("SELECT * FROM users WHERE userId = $userId", map);

    System.out.println("3: extract user from response");
    System.out.println("Query Result: " + response);

    System.out.println("response: " + response.take(AyaseUser.class, 0));
    return response.take(AyaseUser.class, 0);
});

} `

• My AyaseUser.java class:

`public class AyaseUser {
public RecordId id;
public Long userId;
public Long createdAt;

public AyaseUser() {}

public AyaseUser(Long userId, Long createdAt) {
    this.userId = userId;
    this.createdAt = createdAt;
}

@Override
public boolean equals(Object o) {
    if (o == null || getClass() != o.getClass()) return false;
    AyaseUser ayaseUser = (AyaseUser) o;
    return Objects.equals(id, ayaseUser.id) &&
           Objects.equals(userId, ayaseUser.userId) &&
           Objects.equals(createdAt, ayaseUser.createdAt);
}

@Override
public int hashCode() {
    return Objects.hash(id, userId, createdAt);
}

}`

• Error message:

java.lang.NullPointerException: Object instance not found at com.surrealdb.Value.getObject(Native Method) at com.surrealdb.Value.getObject(Value.java:109) at com.surrealdb.ValueClassConverter.convert(ValueClassConverter.java:175) at com.surrealdb.Value.get(Value.java:212) at com.surrealdb.Response.take(Response.java:26) at dev.massi.ayase.database.model.AyaseUser.lambda$findById$0(AyaseUser.java:56) at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1812) at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1804) at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:507) at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1460) at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:2036) at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:189)

• Question:

Should I check response.size() or use Value.isNone() before calling take()?
Is there a recommended way to handle this?

[massikhr]

Bad formatted sorry about that. 😃

[Maji1n]

same here