Prefer IDictionary<,>.TryGetValue() over .Contains() followed by indexer lookup

Author: Bart Koelman

src/JsonApiDotNetCore/Queries/Internal/Parsing/QueryTokenizer.cs

@@ -124,7 +124,7 @@ private bool IsMinusInsideText(TokenKind kind)
 
         private static TokenKind? TryGetSingleCharacterTokenKind(char ch)
         {
-            return SingleCharacterToTokenKinds.ContainsKey(ch) ? SingleCharacterToTokenKinds[ch] : null;
+            return SingleCharacterToTokenKinds.TryGetValue(ch, out TokenKind tokenKind) ? tokenKind : null;
         }
 
         private Token? ProduceTokenFromTextBuffer(bool isQuotedText)

src/JsonApiDotNetCore/Queries/Internal/SparseFieldSetCache.cs

@@ -75,9 +75,10 @@ public IImmutableSet<ResourceFieldAttribute> GetSparseFieldSetForQuery(ResourceT
 
             if (!_visitedTable.ContainsKey(resourceType))
             {
-                SparseFieldSetExpression? inputExpression = _lazySourceTable.Value.ContainsKey(resourceType)
-                    ? new SparseFieldSetExpression(_lazySourceTable.Value[resourceType])
-                    : null;
+                SparseFieldSetExpression? inputExpression =
+                    _lazySourceTable.Value.TryGetValue(resourceType, out IImmutableSet<ResourceFieldAttribute>? inputFields)
+                        ? new SparseFieldSetExpression(inputFields)
+                        : null;
 
                 SparseFieldSetExpression? outputExpression = _resourceDefinitionAccessor.OnApplySparseFieldSet(resourceType, inputExpression);
 
@@ -117,9 +118,10 @@ public IImmutableSet<ResourceFieldAttribute> GetSparseFieldSetForSerializer(Reso
 
             if (!_visitedTable.ContainsKey(resourceType))
             {
-                IImmutableSet<ResourceFieldAttribute> inputFields = _lazySourceTable.Value.ContainsKey(resourceType)
-                    ? _lazySourceTable.Value[resourceType]
-                    : GetResourceFields(resourceType);
+                IImmutableSet<ResourceFieldAttribute> inputFields =
+                    _lazySourceTable.Value.TryGetValue(resourceType, out IImmutableSet<ResourceFieldAttribute>? fields)
+                        ? fields
+                        : GetResourceFields(resourceType);
 
                 var inputExpression = new SparseFieldSetExpression(inputFields);
                 SparseFieldSetExpression? outputExpression = _resourceDefinitionAccessor.OnApplySparseFieldSet(resourceType, inputExpression);

src/JsonApiDotNetCore/Resources/ResourceChangeTracker.cs

@@ -72,9 +72,8 @@ public bool HasImplicitChanges()
             {
                 foreach (string key in _initiallyStoredAttributeValues.Keys)
                 {
-                    if (_requestAttributeValues.ContainsKey(key))
+                    if (_requestAttributeValues.TryGetValue(key, out string? requestValue))
                     {
-                        string requestValue = _requestAttributeValues[key];
                         string actualValue = _finallyStoredAttributeValues[key];
 
                         if (requestValue != actualValue)

src/JsonApiDotNetCore/Resources/ResourceDefinitionAccessor.cs

@@ -82,7 +82,15 @@ public IImmutableSet<IncludeElementExpression> OnApplyIncludes(ResourceType reso
             dynamic resourceDefinition = ResolveResourceDefinition(resourceClrType);
             dynamic handlers = resourceDefinition.OnRegisterQueryableHandlersForQueryStringParameters();
 
-            return handlers != null && handlers!.ContainsKey(parameterName) ? handlers![parameterName] : null;
+            if (handlers != null)
+            {
+                if (handlers.ContainsKey(parameterName))
+                {
+                    return handlers[parameterName];
+                }
+            }
+
+            return null;
         }
 
         /// <inheritdoc />

test/JsonApiDotNetCoreTests/IntegrationTests/InputValidation/RequestBody/WorkflowDefinition.cs

@@ -102,9 +102,8 @@ private static void AssertCanTransitionToStage(WorkflowStage fromStage, Workflow
 
         private static bool CanTransitionToStage(WorkflowStage fromStage, WorkflowStage toStage)
         {
-            if (StageTransitionTable.ContainsKey(fromStage))
+            if (StageTransitionTable.TryGetValue(fromStage, out ICollection<WorkflowStage>? possibleNextStages))
             {
-                ICollection<WorkflowStage> possibleNextStages = StageTransitionTable[fromStage];
                 return possibleNextStages.Contains(toStage);
             }
 

test/JsonApiDotNetCoreTests/IntegrationTests/MultiTenancy/RouteTenantProvider.cs

@@ -25,7 +25,7 @@ public Guid TenantId
                 }
 
                 string? countryCode = (string?)_httpContextAccessor.HttpContext.Request.RouteValues["countryCode"];
-                return countryCode != null && TenantRegistry.ContainsKey(countryCode) ? TenantRegistry[countryCode] : Guid.Empty;
+                return countryCode != null && TenantRegistry.TryGetValue(countryCode, out Guid tenantId) ? tenantId : Guid.Empty;
             }
         }