Android room query return null. Your Query returns a LiveData. If it is an int, the value is the number of rows affected by this query. android. You will have to observe the changes. When the return type is Flow<T?>, querying an empty table emits a null value. Discover how to troubleshoot and resolve the `null` return values when querying a database in Android Room. Dec 16, 2021 · Null values can be a common source of bugs and errors in programming. ast. Code: Entity: Feb 10, 2025 · If a Single<T> query returns null, Room will throw EmptyResultSetException. Kotlin, a statically typed programming language developed by JetBrains, provides several mechanisms to handle null values and ensure safer and more reliable code. Any help? Thanks! This is the DAO @Query("SELECT * FROM BalancesCa May 7, 2021 · I'm new to android and room. You can return arbitrary POJOs from your query methods as long as the fields of the POJO match the column names in the query result. builtintypes androidx. In this article, we will explore how to handle null values in Kotlin when using Room with Flow and empty returns. After the query, the list dataset changes and it will return you the desired correct values. The Docs say: When the return type is Flow<T>, querying an empty table throws a null pointer exception. Note that the insert query works fine. But when I try to select any data it returns an empty list or null values. See full list on developer. operators androidx. ast androidx. builtintypes. The above snippet discusses empty . I don't see any bugs when I run the code except a null pointer exception when I try to print the log for the query. properties androidx. I'm trying to make a local db but I'm struggling at this point where the database is not empty as the image below proves. app androidx. Assuming ViewModel class is something like this: Mar 5, 2020 · How Room handles nullability depends on how you define the return type of the query function. Dec 21, 2023 · In the above method, you are fetching an item in a background thread which means it goes into another thread and allows the return temp_item to always returns immediately, without blocking the code to wait for a result so that’s why you are getting null and or empty list. Nov 26, 2019 · livedata. androidx. query androidx. When the return type is Flow<List<T>>, querying an empty table emits an empty list. value will be null when you first get the LiveData - you have to observe it. It should retrieve the data from DB BalancesCat. Initially, the value is null before the query. Feb 10, 2025 · This well-structured model, combined with Room's robust query validation capabilities, allows your app to consume fewer resources when loading data, improving your app's performance and user experience. UPDATE or DELETE queries can return void or int. appsearch. Jun 14, 2018 · I've been looking at Room query examples but haven't been able to fix the issue. com Troubleshooting null retrieval of Room entity data in Kotlin can be challenging, but by understanding the causes and following the recommended steps, you can overcome these issues. exceptions Jun 16, 2021 · I am trying to get the values from a DB via Room but it always returns null. kurrblm dcgud qfwem jdijd xwnxq ybfnnc kzmxz akhiau anj zco