Quiz app, categories have questions and questions have answers.
I have two queries in the DAO.
In the first one, I get all the categories from the data:
@Query("SELECT * from category_table ORDER BY category_id")
fun getAllCategories(): LiveData<List<Category>>
In the second one, I get a list of questions and answers by category id:
@Query("SELECT * FROM question_table WHERE parent_category_id = :categoryId ")
fun getQuestionsWithAnswersByCategoryId(categoryId: Long): LiveData<List<QuestionWithAnswers>>
Repository:
val getAllCategories: LiveData<List<Category>> = quizDao.getAllCategories()
fun getQuestionsWithAnswersByCategoryId(id: Long): LiveData<List<QuestionWithAnswers>> {
return quizDao.getQuestionWithAnswers(id)
}
This is my viewmodel:
val getAllCategories: LiveData<List<Category>>
var questionById: LiveData<List<QuestionWithAnswers>>
init {
getAllCategories = repository.getAllCategories
questionByCategoryId = repository.getQuestionWithAnswersByCategoryId(???????)
}
The problem is that I don't know the categories' id beforehand and need to obtain them from the database.
when I try to obtain a category id in the viewmodel like this:
var categoryId = getAllCategories.value[0].categoryId
it returns null.
Is there any way to obtain categories id which wrapped in livedata inside a viewmodel?
