Problems with Linq

Question

Hello

I am using firebase, to make a note-taking app.

I am using this documentation

https://firebase.google.com/docs/reference/rest/auth

and this is my auth

  using (HttpClient client = new HttpClient()) {  
                var bodyJson = JsonConvert.SerializeObject(new {  
                    email = user.Email,  
                    password = user.Password,  
                    returnSecureToken = true });  
  
                var data = new StringContent(bodyJson, Encoding.UTF8, "application/json");  
  
                var response = await client.PostAsync  
                    ($"https://identitytoolkit.googleapis.com/v1/accounts:signUp?key={FirebaseKey}", data);  
                if (response.IsSuccessStatusCode) {  
                    string resutJson = await response.Content.ReadAsStringAsync();  
                    var res = JsonConvert.DeserializeObject<AuthResult>(resutJson);  
                    App.UserId = res.localId;  
                    Console.WriteLine($"**************************Register : {res.email} with token {res.localId}");  
  
                    return true;  
  
                } else {  
                    string errorJson = await response.Content.ReadAsStringAsync();  
                    var res = JsonConvert.DeserializeObject<AuthError>(errorJson);  
                    DispayError(res);  
  
                    return false;  
                }  
            }  
        }  
        public static async Task<bool> LoginUser(User user) {  
  
            using (HttpClient client = new HttpClient()) {  
                var bodyJson = JsonConvert.SerializeObject(new {  
                    email = user.Email,  
                    password = user.Password,  
                    returnSecureToken = true  
                });  
  
                var data = new StringContent(bodyJson, Encoding.UTF8, "application/json");  
  
                var response = await client.PostAsync  
                    ($"https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?key={FirebaseKey}", data);  
                if (response.IsSuccessStatusCode) {  
                    string resutJson = await response.Content.ReadAsStringAsync();  
                    var res = JsonConvert.DeserializeObject<AuthResult>(resutJson);  
                    App.UserId = res.localId;  
                    Console.WriteLine($"**************************Login : {res.email} with token {res.localId}");  
                    return true;  
  
                } else {  
                    string errorJson = await response.Content.ReadAsStringAsync();  
                    var res = JsonConvert.DeserializeObject<AuthError>(errorJson);  
                    DispayError(res);  
  
                    return false;  
                }  
            }  
        }  
  
        private static void DispayError(AuthError res) {  
            Application.Current.MainPage.DisplayAlert("Error", res.error.message, "OK");  
        }  

When the user logs in, I grabbed the user UID of firebase, and get the notebooks, and the notes within that notebook

The brig problem is that for some reason, my notebook variable gets emptied

  private async void GetNotebooksAsync() {  
            var notebooks = await Database.ReadAsync<Notebook>();  
            if (notebooks != null) {  
                notebooks = notebooks.Where(book => book.Id == App.UserId).ToList();  
                NotebooksCollection.Clear();  
                foreach (var item in notebooks)  
                {  
                    NotebooksCollection.Add(item);  
                }  
  
            }  
        }  

The strange part is that I am filtering by the UserId of the notebook, and as you can see
the user ******@a.com with the id of 8zOEcqbNxxxxxxxx4qVRSpWEv2 has one notebook

So I do not understand by the filter do not work

here is my project if you want to test it

https://github.com/eduardoagr/safe.Xamarin/tree/main/Safe

Furthermore, you can log in with ******@a.com/ // this user has one notebook assigned to it

user ******@b.com does not have a notebook

And if I do

   var notebooks = await Database.ReadAsync<Notebook>();  
        if (notebooks != null) {  
            notebooks.Where(book => book.Id == App.UserId).ToList();  
            NotebooksCollection.Clear();  
            foreach (var item in notebooks)  
            {  
                NotebooksCollection.Add(item);  
            }  

if I do that I can see the same notebook in user ******@a.com and ******@b.com

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

Firstly, I add the breakpoint in the ReadAsync method of Database.cs, I find it always return null, So I change the code like following code snap. then I can get the correct result with ******@a.com account

   public static async Task<List<T>> ReadAsync<T>() where T : HasId {  
     
               using (HttpClient client = new HttpClient ()) {  
                   var res = await client.GetAsync($"{FirebadeDb}{typeof(T).Name.ToLower()}.json");  
                   List<T> objts = new List<T>();  
                   var JsonRes = await res.Content.ReadAsStringAsync();  
                   if (res.IsSuccessStatusCode) {  
                       var valuePairs = JsonConvert.DeserializeObject<Dictionary<string, T>>(JsonRes);  
                       if (valuePairs != null) {  
                          
                           foreach (var item in valuePairs) {  
     
                               item.Value.Id = item.Key;  
                               objts.Add(item.Value);  
                           }  
                            
                       }  
                       return objts;  
     
                   } else {  
                       return null;  
                   }  
     
                   //return null;  
               }  
           }  

Then, I find you compare book => book.Id == App.UserId in the GetNotebooksAsync method, it is different id. so you always get the null result. so I compare with book => book.UserId == App.UserId like following code snap.

   private async void GetNotebooksAsync() {  
               var notebooks = await Database.ReadAsync<Notebook>();  
               if (notebooks != null) {  
                   //notebooks = notebooks.Where(book => book.Id == App.UserId).ToList();  
                   notebooks = notebooks.Where(book => book.UserId == App.UserId).ToList();  
                   NotebooksCollection.Clear();  
                   foreach (var item in notebooks)  
                   {  
                       NotebooksCollection.Add(item);  
                   }  
     
               }  
           }  

Then I can get the correct result.

Best Regards,

Leon Lu

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