Searching our data

We will implement an Android search widget in our fragment, allowing the user to search for articles by typing in a query. When the search is executed, the query will be sent to a function for processing, and the search will be performed.

Implementing search functionality

We’ll implement a search feature that allows users to search for specific articles by typing in the source, publishing company, or author’s name. This is done by subscribing to an observer in the ViewModel and passing the latest data as a search query to the searchNews() method within a coroutine. The searchNews() method takes in a search query as one of its arguments and uses it to request the API to perform the desired search.

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class SearchNewsFragment : Fragment(R.layout.fragment_search_news) {
    lateinit var viewModel: NewsViewModel
    lateinit var newsAdapter: NewsAdapter
    lateinit var binding: FragmentSearchNewsBinding
    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        binding = FragmentSearchNewsBinding.bind(view)
        val newsRepository = NewsRepository(ArticleDatabase(requireContext() as NewsActivity))
        val viewModelProviderFactory =
            NewsViewModelProvider(activity?.application!!, newsRepository)
        viewModel = ViewModelProvider(this, viewModelProviderFactory).get(NewsViewModel::class.java)
        setUpRecyclerView(binding)
        newsAdapter.setOnItemClickListener {
            val bundle = Bundle().apply {
                putSerializable("article", it)
            }
            findNavController().navigate(
                R.id.action_searchNewsFragment2_to_articleFragment,
                bundle
            )
        }
        var job: Job? = null
        binding.editTextSearch.addTextChangedListener { editable ->
            job?.cancel()
            job = MainScope().launch {
                delay(Constants.SEARCH_NEWS_TIME_DELAY)
                editable?.let {
                    if (editable.toString().isNotEmpty()) {
                        viewModel.searchNews(editable.toString())
                    }
                }
            }
        }
        viewModel.searchNews.observe(viewLifecycleOwner, Observer { response ->
            response.data?.let { newsResponse ->
                newsAdapter.differ.submitList(newsResponse.articles.toList())
                val totalPages = newsResponse.totalResults
                isLastPage = viewModel.searchNewsPage == totalPages
            }
        })
    }
    private fun setUpRecyclerView(binding: FragmentSearchNewsBinding) {
        newsAdapter = NewsAdapter()
        binding.searchNewsRecyclerView.apply {
            adapter = newsAdapter
            layoutManager = LinearLayoutManager(activity)
            addOnScrollListener(this@SearchNewsFragment.scrollListener)
        }
    }
    private fun hideProgressBar(binding: FragmentSearchNewsBinding) {
        binding.paginationProgressBar.visibility = View.INVISIBLE
        isLoading = false
    }
    private fun showProgressBar(binding: FragmentSearchNewsBinding) {
        binding.paginationProgressBar.visibility = View.VISIBLE
        isLoading = false
    }
    var isLastPage = false
    var isLoading = false
    var isScrolling = false
    val scrollListener = object : RecyclerView.OnScrollListener() {
        override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
            super.onScrolled(recyclerView, dx, dy)
            val layoutManager = recyclerView.layoutManager as LinearLayoutManager
            val firstVisibleItemPosition = layoutManager.findFirstVisibleItemPosition()
            val visibleItemCount = layoutManager.childCount
            val totalItemCount = layoutManager.itemCount
            val isNotLoadingAndNotLastPage = !isLoading && !isLastPage
            val isAtLastItem = firstVisibleItemPosition + visibleItemCount >= totalItemCount
            val isNotAtBeginning = firstVisibleItemPosition >= 0
            val isTotalMoreThanVisible = totalItemCount >= Constants.QUERY_PAGE_SIZE
            val shouldPaginate = isNotLoadingAndNotLastPage && isAtLastItem && isNotAtBeginning &&
                    isTotalMoreThanVisible && isScrolling
            if (shouldPaginate) {
                viewModel.searchNews(binding.editTextSearch.text.toString())
                isScrolling = false
            } else {
                binding.searchNewsRecyclerView.setPadding(0, 0, 0, 0)
            }
        }
        override fun onScrollStateChanged(recyclerView: RecyclerView, newState: Int) {
            super.onScrollStateChanged(recyclerView, newState)
            if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
                isScrolling = true
            }
        }
    }
}

Introduction

MVVM Architecture

Layouts

Layout Design Assessment

API

Android Web Services Assessment

Utility Classes

Repository Pattern

ViewModel Pattern

Android Business Logic Assessment

Views

Conclusion

Appendix

Search News Fragment

Searching our data

Implementing search functionality