Added checking of parameters to avoid NPEs

Author: topnax

WebFrontend/App.razor

@@ -7,9 +7,22 @@
         </MatThemeProvider>
     </Found>
     <NotFound>
-        <LayoutView Layout="@typeof(MainLayout)">
-            <p>Sorry, there's nothing at this address.</p>
-        </LayoutView>
+        <MatThemeProvider Theme="appTheme">
+            <LayoutView Layout="@typeof(MainLayout)">
+                <div class="mat-layout-grid mat-layout-grid-align-center">
+                    <div class="mat-layout-grid-inner center">
+
+                        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-2"></div>
+                        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-8">
+                            <MatPaper Elevation="2" style="padding:1em">
+                                <span>There is nothing at this address.</span>
+                            </MatPaper>
+                        </div>
+                        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-2"></div>
+                    </div>
+                </div>
+            </LayoutView>
+        </MatThemeProvider>
     </NotFound>
 </Router>
 
@@ -21,4 +34,4 @@
     {
         Primary = MatThemeColors.BlueGrey._500.Value
     };
-}
+}

WebFrontend/Pages/EditMarketOrder.razor

@@ -54,6 +54,13 @@
     {
         // fetch the order to be edited
         _activeMarketOrder = MarketOrderService.GetMarketOrder(OrderId);
+
+        if (_activeEntry == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+            
         _activeEntry = PortfolioEntrySerivce.GetPortfolioEntry(_activeMarketOrder.PortfolioEntryId);
         _activePortfolio = PortfolioService.GetPortfolio(_activeEntry.PortfolioId);
 

WebFrontend/Pages/EditPortfolio.razor

@@ -65,6 +65,12 @@
         // find the portfolio
         _activePortfolio = PortfolioService.GetPortfolio(PortfolioId);
 
+        if (_activePortfolio == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+        
         // update the form model
         _formFormModel.Name = _activePortfolio.Name;
         _formFormModel.Description = _activePortfolio.Description;

WebFrontend/Pages/NewMarketOrder.razor

@@ -48,6 +48,12 @@
         // load the portfolio entry
         _activeEntry = PortfolioEntrySerivce.GetPortfolioEntry(EntryId);
 
+        if (_activeEntry == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+        
         // load the portfolio the entry belongs to
         _activePortfolio = PortfolioService.GetPortfolio(_activeEntry.PortfolioId);
     }

WebFrontend/Pages/PortfolioDetail.razor

@@ -126,22 +126,33 @@
 
 @code
 {
+    // id of the portfolio whose detail should be shown
     [Parameter]
     public int PortfolioId { get; set; }
 
+    // portfolio whose detail should be shown
     private Portfolio _activePortfolio;
 
+    // summary of the portfolio
     private ISummaryService.Summary _portfolioSummary;
 
+    // entries of the portfolio
     private List<PortfolioEntry> _activePortfolioEntries;
 
+    // rows of the portfolio entry table
     private List<PortfolioEntryRow> _portfolioEntryRows;
 
     protected record PortfolioEntryRow(string Symbol, decimal CurrentPrice, decimal RelativeChange, decimal Percentage, decimal AbsoluteChange, decimal MarketValue, int EntryId);
 
     protected override void OnInitialized()
     {
         _activePortfolio = PortfolioService.GetPortfolio(PortfolioId);
+        if (_activePortfolio == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+        
         _activePortfolioEntries = PortfolioEntryService.GetPortfolioEntries(PortfolioId);
         _loadEntryInfo();
     }

WebFrontend/Pages/PortfolioEntryDetail.razor

@@ -254,6 +254,12 @@
         // get the portfolio entry
         _activePortfolioEntry = PortfolioEntryService.GetPortfolioEntry(EntryId);
 
+        if (_activePortfolioEntry == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+        
         // get the entry's portfolio
         _activePortfolio = PortfolioService.GetPortfolio(_activePortfolioEntry.PortfolioId);
     }

WebFrontend/Pages/PortfolioEntryManagement.razor

@@ -112,6 +112,12 @@
         // load the portfolio using the specified ID
         _portfolio = PortfolioService.GetPortfolio(PortfolioId);
 
+        if (_portfolio == null)
+        {
+            NavigationManager.NavigateTo("/notfound");
+            return;
+        }
+        
         // load all entries of the portfolio
         _portfolioEntries = PortfolioEntryService.GetPortfolioEntries(PortfolioId);
     }

WebFrontend/Pages/ResourceNotFound.razor

@@ -0,0 +1,50 @@
+@page "/notfound"
+@using Services
+@inject NavigationManager NavigationManager
+@inject IPortfolioService PortfolioService
+@inject IPortfolioEntryService PortfolioEntryService
+@inject IMatDialogService MatDialogService
+@inject IMatToaster Toaster
+
+<style>
+    .demo-mat-card {
+        margin-bottom: 2em;
+    }
+
+    .demo-mat-card-content {
+        padding: 1rem;
+    }
+
+    .clear-margin {
+        margin: 0px;
+    }
+    
+    .app-fab--absolute {
+        position: fixed;
+        bottom: 1rem;
+        right: 1rem;
+    }
+    
+    .mat-paper {
+        display: flex;
+        flex-direction: column;
+        justify-content: center;
+        align-items: center;
+        padding: 1em;
+    } 
+</style>
+<div class="mat-layout-grid mat-layout-grid-align-center">
+    <div class="mat-layout-grid-inner center">
+
+        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-2"></div>
+        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-8">
+            <MatPaper Elevation="2">
+                <span>Resource not found</span>
+                <div>
+                    <MatButton Style="margin-top:1em;" Label="Back to portfolio list" OnClick='() => { NavigationManager.NavigateTo($"/"); }'></MatButton>
+                </div>
+            </MatPaper>
+        </div>
+        <div class="mat-layout-grid-cell mat-layout-grid-cell-span-2"></div>
+    </div>
+</div>