Use of unassigned local variable. How to resolve?

Question

I’m developing a site that requests an api and shows the data to users, but I’m having problems:

Use of unassigned local variable 'value'

Use of unassigned local variable 'date'

To better understand:

Page code with error:

public class IndexModel : PageModel
  {
    private readonly ILogger<IndexModel> _logger;
    public Global Global { get; private set; }
    public Country[] Countries { get; private set; }
    public DateTime Date { get; private set; }
    public IMemoryCache MemoryCache { get; private set; }
    public IndexModel(ILogger<IndexModel> logger, IMemoryCache memoryCache)
    {
      _logger = logger;
      MemoryCache = memoryCache;
    }

    public async Task OnGetAsync()
    {
      try
      {
        string key_countries = "countries_cache"; // Chave do cache.
        string key_global = "global_cache";
        string key_date = "date_cache";
        if (!MemoryCache.TryGetValue<Country[]>(key_countries, out Country[] values) &&
            (!MemoryCache.TryGetValue<Global>(key_global, out Global value) &&
              (!MemoryCache.TryGetValue<DateTime>(key_date, out DateTime date)))) // Verifica se há dados em cache.
        {
          var create = RestService.For<IGetRoot>("https://api.covid19api.com/summary");
          var result = await create.GetAsync(); // sou var result = create.GetAsync().GetAwaiter().GetResult();
          _logger.LogInformation(result.ToString());
          Global = result.Global;
          Countries = result.Countries;
          Date = result.Date;
          MemoryCache.Set(key_countries, Countries, System.TimeSpan.FromMinutes(30)); // Salva os dados em cache e define um tempo de expiração
          MemoryCache.Set(key_global, Global, System.TimeSpan.FromMinutes(30));
          MemoryCache.Set(key_date, Date, System.TimeSpan.FromMinutes(30));
        }
        else
        {
          Global = value;
          Countries = values;
          Date = date;
        }
      }
      catch (Exception e)
      {
        _logger.LogInformation("Erro na requisição http: " + e.Message);
      }
    }
  }

Answer 1

Note that your variables are in different scopes/blocks, state them before the if-else and correct the TryGetValue by removing the data type after the parameter out.

DateTime date = DateTime.MinValue;
Global value = null;
Country[] values = null;

if (!MemoryCache.TryGetValue<Country[]>(key_countries, out values) &&
    (!MemoryCache.TryGetValue<Global>(key_global, out value) &&
        (!MemoryCache.TryGetValue<DateTime>(key_date, out date)))) // Verifica se há dados em cache.
{
    var create = RestService.For<IGetRoot>("https://api.covid19api.com/summary");
    var result = await create.GetAsync(); // sou var result = create.GetAsync().GetAwaiter().GetResult();
    _logger.LogInformation(result.ToString());
    Global = result.Global;
    Countries = result.Countries;
    Date = result.Date;
    MemoryCache.Set(key_countries, Countries, System.TimeSpan.FromMinutes(30)); // Salva os dados em cache e define um tempo de expiração
    MemoryCache.Set(key_global, Global, System.TimeSpan.FromMinutes(30));
    MemoryCache.Set(key_date, Date, System.TimeSpan.FromMinutes(30));
}
else
{
    Global = value;
    Countries = values;
    Date = date;
}