From 53b0980df09b75cfd3483e15fc537f6eae1d5313 Mon Sep 17 00:00:00 2001
From: Martin Costello <martin@martincostello.com>
Date: Mon, 31 Oct 2022 20:07:10 +0000
Subject: Use TryGetValue() for dictionary lookup (#44791)

Use `TryGetValue()` instead of `ContainsKey()` and the indexer.
---
 src/Features/JsonPatch/src/Internal/DictionaryAdapterOfTU.cs  |  4 +---
 .../Authentication.Core/src/AuthenticationSchemeProvider.cs   |  5 ++---
 src/Identity/Core/src/SignInManager.cs                        | 11 +++--------
 3 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/src/Features/JsonPatch/src/Internal/DictionaryAdapterOfTU.cs b/src/Features/JsonPatch/src/Internal/DictionaryAdapterOfTU.cs
index 6dc39a5376..6dce130d73 100644
--- a/src/Features/JsonPatch/src/Internal/DictionaryAdapterOfTU.cs
+++ b/src/Features/JsonPatch/src/Internal/DictionaryAdapterOfTU.cs
@@ -147,7 +147,7 @@ public class DictionaryAdapter<TKey, TValue> : IAdapter
         }
 
         // As per JsonPatch spec, the target location must exist for test to be successful
-        if (!dictionary.ContainsKey(convertedKey))
+        if (!dictionary.TryGetValue(convertedKey, out var currentValue))
         {
             errorMessage = Resources.FormatTargetLocationAtPathSegmentNotFound(segment);
             return false;
@@ -158,8 +158,6 @@ public class DictionaryAdapter<TKey, TValue> : IAdapter
             return false;
         }
 
-        var currentValue = dictionary[convertedKey];
-
         // The target segment does not have an assigned value to compare the test value with
         if (currentValue == null)
         {
diff --git a/src/Http/Authentication.Core/src/AuthenticationSchemeProvider.cs b/src/Http/Authentication.Core/src/AuthenticationSchemeProvider.cs
index bab572a374..1881ff157c 100644
--- a/src/Http/Authentication.Core/src/AuthenticationSchemeProvider.cs
+++ b/src/Http/Authentication.Core/src/AuthenticationSchemeProvider.cs
@@ -184,15 +184,14 @@ public class AuthenticationSchemeProvider : IAuthenticationSchemeProvider
     /// <param name="name">The name of the authenticationScheme being removed.</param>
     public virtual void RemoveScheme(string name)
     {
-        if (!_schemes.ContainsKey(name))
+        if (!_schemes.TryGetValue(name, out var scheme))
         {
             return;
         }
         lock (_lock)
         {
-            if (_schemes.ContainsKey(name))
+            if (_schemes.TryGetValue(name, out scheme))
             {
-                var scheme = _schemes[name];
                 if (_requestHandlers.Remove(scheme))
                 {
                     _requestHandlersCopy = _requestHandlers.ToArray();
diff --git a/src/Identity/Core/src/SignInManager.cs b/src/Identity/Core/src/SignInManager.cs
index e6af0da9de..9b93a56d23 100644
--- a/src/Identity/Core/src/SignInManager.cs
+++ b/src/Identity/Core/src/SignInManager.cs
@@ -652,26 +652,21 @@ public class SignInManager<TUser> where TUser : class
     {
         var auth = await Context.AuthenticateAsync(IdentityConstants.ExternalScheme);
         var items = auth?.Properties?.Items;
-        if (auth?.Principal == null || items == null || !items.ContainsKey(LoginProviderKey))
+        if (auth?.Principal == null || items == null || !items.TryGetValue(LoginProviderKey, out var provider))
         {
             return null;
         }
 
         if (expectedXsrf != null)
         {
-            if (!items.ContainsKey(XsrfKey))
-            {
-                return null;
-            }
-            var userId = items[XsrfKey] as string;
-            if (userId != expectedXsrf)
+            if (!items.TryGetValue(XsrfKey, out var userId) ||
+                userId != expectedXsrf)
             {
                 return null;
             }
         }
 
         var providerKey = auth.Principal.FindFirstValue(ClaimTypes.NameIdentifier);
-        var provider = items[LoginProviderKey] as string;
         if (providerKey == null || provider == null)
         {
             return null;
-- 
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