diff --git a/src/TableauSharp/Common/Models/ErrorResponse.cs b/src/TableauSharp/Common/Models/ErrorResponse.cs
index bde5431..9d645fd 100644
--- a/src/TableauSharp/Common/Models/ErrorResponse.cs
+++ b/src/TableauSharp/Common/Models/ErrorResponse.cs
@@ -5,11 +5,11 @@ namespace TableauSharp.Common.Models;
 public class ErrorResponse
 {
     [JsonPropertyName("code")]
-    public string Code { get; set; }
+    public string Code { get; set; } = string.Empty;
 
     [JsonPropertyName("summary")]
-    public string Summary { get; set; }
+    public string Summary { get; set; } = string.Empty;
 
     [JsonPropertyName("detail")]
-    public string Detail { get; set; }
-}
\ No newline at end of file
+    public string Detail { get; set; } = string.Empty;
+}
diff --git a/src/TableauSharp/Embedding/Models/TrustedTicketRequest.cs b/src/TableauSharp/Embedding/Models/TrustedTicketRequest.cs
index 1e19dc8..f0350a3 100644
--- a/src/TableauSharp/Embedding/Models/TrustedTicketRequest.cs
+++ b/src/TableauSharp/Embedding/Models/TrustedTicketRequest.cs
@@ -2,7 +2,7 @@ namespace TableauSharp.Embedding.Models;
 
 public class TrustedTicketRequest
 {
-    public string Username { get; set; }
-    public string ClientIp { get; set; }
-    public string TargetSite { get; set; }
-}
\ No newline at end of file
+    public string Username { get; set; } = string.Empty;
+    public string? ClientIp { get; set; }
+    public string? TargetSite { get; set; }
+}
diff --git a/src/TableauSharp/Embedding/Models/TrustedTicketResponse.cs b/src/TableauSharp/Embedding/Models/TrustedTicketResponse.cs
index 4733ee5..cb231c2 100644
--- a/src/TableauSharp/Embedding/Models/TrustedTicketResponse.cs
+++ b/src/TableauSharp/Embedding/Models/TrustedTicketResponse.cs
@@ -2,6 +2,6 @@ namespace TableauSharp.Embedding.Models;
 
 public class TrustedTicketResponse
 {
-    public string TicketId { get; set; }
-    public string EmbedUrl { get; set; }
-}
\ No newline at end of file
+    public string TicketId { get; set; } = string.Empty;
+    public string EmbedUrl { get; set; } = string.Empty;
+}
diff --git a/src/TableauSharp/Embedding/Services/EmbeddingService.cs b/src/TableauSharp/Embedding/Services/EmbeddingService.cs
index 75269b0..b06ab0c 100644
--- a/src/TableauSharp/Embedding/Services/EmbeddingService.cs
+++ b/src/TableauSharp/Embedding/Services/EmbeddingService.cs
@@ -40,10 +40,14 @@ public async Task<TrustedTicketResponse> GetTrustedTicketAsync(TrustedTicketRequ
 
         var form = new Dictionary<string, string>
         {
-            { "username", request.Username },
-            { "target_site", request.TargetSite }
+            { "username", request.Username }
         };
 
+        if (!string.IsNullOrEmpty(request.TargetSite))
+        {
+            form.Add("target_site", request.TargetSite);
+        }
+
         if (!string.IsNullOrEmpty(request.ClientIp))
         {
             form.Add("client_ip", request.ClientIp);
diff --git a/src/TableauSharp/Permissions/Models/PermissionCapabilityAssignment.cs b/src/TableauSharp/Permissions/Models/PermissionCapabilityAssignment.cs
index b91493a..72f5c30 100644
--- a/src/TableauSharp/Permissions/Models/PermissionCapabilityAssignment.cs
+++ b/src/TableauSharp/Permissions/Models/PermissionCapabilityAssignment.cs
@@ -9,5 +9,5 @@ public class PermissionCapabilityAssignment
     public PermissionCapability Capability { get; set; }
 
     [JsonPropertyName("mode")]
-    public string Mode { get; set; } // "Allow" or "Deny"
-}
\ No newline at end of file
+    public string Mode { get; set; } = string.Empty; // "Allow" or "Deny"
+}
diff --git a/src/TableauSharp/Permissions/Models/PermissionSyncRequest.cs b/src/TableauSharp/Permissions/Models/PermissionSyncRequest.cs
index b876c1a..21f1a59 100644
--- a/src/TableauSharp/Permissions/Models/PermissionSyncRequest.cs
+++ b/src/TableauSharp/Permissions/Models/PermissionSyncRequest.cs
@@ -2,6 +2,6 @@ namespace TableauSharp.Permissions.Models;
 
 public class PermissionSyncRequest
 {
-    public string TargetId { get; set; }
+    public string TargetId { get; set; } = string.Empty;
     public List<TableauPermission> Permissions { get; set; } = new();
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Permissions/Models/TableauPermission.cs b/src/TableauSharp/Permissions/Models/TableauPermission.cs
index 99788a6..51e598c 100644
--- a/src/TableauSharp/Permissions/Models/TableauPermission.cs
+++ b/src/TableauSharp/Permissions/Models/TableauPermission.cs
@@ -5,11 +5,11 @@ namespace TableauSharp.Permissions.Models;
 public class TableauPermission
 {
     [JsonPropertyName("granteeId")]
-    public string GranteeId { get; set; }
+    public string GranteeId { get; set; } = string.Empty;
 
     [JsonPropertyName("granteeType")]
-    public string GranteeType { get; set; } // "User" or "Group"
+    public string GranteeType { get; set; } = string.Empty; // "User" or "Group"
 
     [JsonPropertyName("capabilities")]
     public List<PermissionCapabilityAssignment> Capabilities { get; set; } = new();
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Projects/Models/ProjectCreateRequest.cs b/src/TableauSharp/Projects/Models/ProjectCreateRequest.cs
index d1a52fd..5f0193d 100644
--- a/src/TableauSharp/Projects/Models/ProjectCreateRequest.cs
+++ b/src/TableauSharp/Projects/Models/ProjectCreateRequest.cs
@@ -2,7 +2,7 @@ namespace TableauSharp.Projects.Models;
 
 public class ProjectCreateRequest
 {
-    public string Name { get; set; }
-    public string Description { get; set; }
-    public string ParentProjectId { get; set; }
-}
\ No newline at end of file
+    public string Name { get; set; } = string.Empty;
+    public string? Description { get; set; }
+    public string? ParentProjectId { get; set; }
+}
diff --git a/src/TableauSharp/Projects/Models/ProjectUpdateRequest.cs b/src/TableauSharp/Projects/Models/ProjectUpdateRequest.cs
index 55638ff..e26e1c2 100644
--- a/src/TableauSharp/Projects/Models/ProjectUpdateRequest.cs
+++ b/src/TableauSharp/Projects/Models/ProjectUpdateRequest.cs
@@ -2,6 +2,6 @@ namespace TableauSharp.Projects.Models;
 
 public class ProjectUpdateRequest
 {
-    public string Name { get; set; }
-    public string Description { get; set; }
-}
\ No newline at end of file
+    public string? Name { get; set; }
+    public string? Description { get; set; }
+}
diff --git a/src/TableauSharp/Projects/Models/TableauProject.cs b/src/TableauSharp/Projects/Models/TableauProject.cs
index 3c8fa35..a664c8d 100644
--- a/src/TableauSharp/Projects/Models/TableauProject.cs
+++ b/src/TableauSharp/Projects/Models/TableauProject.cs
@@ -5,17 +5,17 @@ namespace TableauSharp.Projects.Models;
 public class TableauProject
 {
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = string.Empty;
 
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = string.Empty;
 
     [JsonPropertyName("description")]
-    public string Description { get; set; }
+    public string? Description { get; set; }
 
     [JsonPropertyName("parentProjectId")]
-    public string ParentProjectId { get; set; }
+    public string? ParentProjectId { get; set; }
 
     [JsonPropertyName("ownerId")]
-    public string OwnerId { get; set; }
-}
\ No newline at end of file
+    public string? OwnerId { get; set; }
+}
diff --git a/src/TableauSharp/Projects/Services/ProjectService.cs b/src/TableauSharp/Projects/Services/ProjectService.cs
index a651d2e..ec0c103 100644
--- a/src/TableauSharp/Projects/Services/ProjectService.cs
+++ b/src/TableauSharp/Projects/Services/ProjectService.cs
@@ -31,9 +31,9 @@ public async Task<IEnumerable<TableauProject>> GetAllAsync(CancellationToken can
         {
             projects.Add(new TableauProject
             {
-                Id = p.GetProperty("id").GetString(),
-                Name = p.GetProperty("name").GetString(),
-                Description = p.GetProperty("description").GetString(),
+                Id = p.GetProperty("id").GetString() ?? string.Empty,
+                Name = p.GetProperty("name").GetString() ?? string.Empty,
+                Description = p.TryGetProperty("description", out var description) ? description.GetString() : null,
                 ParentProjectId = p.TryGetProperty("parentProjectId", out var parent) ? parent.GetString() : null,
                 OwnerId = p.GetProperty("owner").GetProperty("id").GetString()
             });
@@ -55,9 +55,9 @@ public async Task<TableauProject> GetByIdAsync(string projectId, CancellationTok
 
         return new TableauProject
         {
-            Id = p.GetProperty("id").GetString(),
-            Name = p.GetProperty("name").GetString(),
-            Description = p.GetProperty("description").GetString(),
+            Id = p.GetProperty("id").GetString() ?? string.Empty,
+            Name = p.GetProperty("name").GetString() ?? string.Empty,
+            Description = p.TryGetProperty("description", out var description) ? description.GetString() : null,
             ParentProjectId = p.TryGetProperty("parentProjectId", out var parent) ? parent.GetString() : null,
             OwnerId = p.GetProperty("owner").GetProperty("id").GetString()
         };
@@ -80,9 +80,9 @@ public async Task<TableauProject> CreateAsync(ProjectCreateRequest request, Canc
 
         return new TableauProject
         {
-            Id = p.GetProperty("id").GetString(),
-            Name = p.GetProperty("name").GetString(),
-            Description = p.GetProperty("description").GetString(),
+            Id = p.GetProperty("id").GetString() ?? string.Empty,
+            Name = p.GetProperty("name").GetString() ?? string.Empty,
+            Description = p.TryGetProperty("description", out var description) ? description.GetString() : null,
             ParentProjectId = p.TryGetProperty("parentProjectId", out var parent) ? parent.GetString() : null,
             OwnerId = p.GetProperty("owner").GetProperty("id").GetString()
         };
@@ -105,9 +105,9 @@ public async Task<TableauProject> UpdateAsync(string projectId, ProjectUpdateReq
 
         return new TableauProject
         {
-            Id = p.GetProperty("id").GetString(),
-            Name = p.GetProperty("name").GetString(),
-            Description = p.GetProperty("description").GetString(),
+            Id = p.GetProperty("id").GetString() ?? string.Empty,
+            Name = p.GetProperty("name").GetString() ?? string.Empty,
+            Description = p.TryGetProperty("description", out var description) ? description.GetString() : null,
             ParentProjectId = p.TryGetProperty("parentProjectId", out var parent) ? parent.GetString() : null,
             OwnerId = p.GetProperty("owner").GetProperty("id").GetString()
         };
diff --git a/src/TableauSharp/TableauSharp.csproj b/src/TableauSharp/TableauSharp.csproj
index 3eac46d..30958c0 100644
--- a/src/TableauSharp/TableauSharp.csproj
+++ b/src/TableauSharp/TableauSharp.csproj
@@ -4,6 +4,7 @@
     <TargetFramework>net8.0</TargetFramework>
     <ImplicitUsings>enable</ImplicitUsings>
     <Nullable>enable</Nullable>
+    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
 
     <!-- NuGet package metadata -->
     <PackageId>TableauSharp</PackageId>
diff --git a/src/TableauSharp/Users/Models/GroupCreateRequest.cs b/src/TableauSharp/Users/Models/GroupCreateRequest.cs
index c5c62de..36ba500 100644
--- a/src/TableauSharp/Users/Models/GroupCreateRequest.cs
+++ b/src/TableauSharp/Users/Models/GroupCreateRequest.cs
@@ -2,5 +2,5 @@ namespace TableauSharp.Users.Models;
 
 public class GroupCreateRequest
 {
-    public string Name { get; set; }
-}
\ No newline at end of file
+    public string Name { get; set; } = string.Empty;
+}
diff --git a/src/TableauSharp/Users/Models/TableauGroup.cs b/src/TableauSharp/Users/Models/TableauGroup.cs
index d92bf86..4307705 100644
--- a/src/TableauSharp/Users/Models/TableauGroup.cs
+++ b/src/TableauSharp/Users/Models/TableauGroup.cs
@@ -5,11 +5,11 @@ namespace TableauSharp.Users.Models;
 public class TableauGroup
 {
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = string.Empty;
 
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = string.Empty;
 
     [JsonPropertyName("users")]
     public List<TableauUser> Users { get; set; } = new();
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Users/Models/TableauUser.cs b/src/TableauSharp/Users/Models/TableauUser.cs
index fad0fc3..2581ff3 100644
--- a/src/TableauSharp/Users/Models/TableauUser.cs
+++ b/src/TableauSharp/Users/Models/TableauUser.cs
@@ -5,20 +5,20 @@ namespace TableauSharp.Users.Models;
 public class TableauUser
 {
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = string.Empty;
 
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = string.Empty;
 
     [JsonPropertyName("fullName")]
-    public string FullName { get; set; }
+    public string? FullName { get; set; }
 
     [JsonPropertyName("email")]
-    public string Email { get; set; }
+    public string? Email { get; set; }
 
     [JsonPropertyName("siteRole")]
-    public string SiteRole { get; set; }
+    public string SiteRole { get; set; } = string.Empty;
 
     [JsonPropertyName("isActive")]
     public bool IsActive { get; set; }
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Users/Models/UserCreateRequest.cs b/src/TableauSharp/Users/Models/UserCreateRequest.cs
index 71176c2..0ee02b4 100644
--- a/src/TableauSharp/Users/Models/UserCreateRequest.cs
+++ b/src/TableauSharp/Users/Models/UserCreateRequest.cs
@@ -2,7 +2,7 @@ namespace TableauSharp.Users.Models;
 
 public class UserCreateRequest
 {
-    public string Name { get; set; }
-    public string Email { get; set; }
-    public string SiteRole { get; set; }
-}
\ No newline at end of file
+    public string Name { get; set; } = string.Empty;
+    public string? Email { get; set; }
+    public string SiteRole { get; set; } = string.Empty;
+}
diff --git a/src/TableauSharp/Users/Models/UserUpdateRequest.cs b/src/TableauSharp/Users/Models/UserUpdateRequest.cs
index 0677bad..72b5601 100644
--- a/src/TableauSharp/Users/Models/UserUpdateRequest.cs
+++ b/src/TableauSharp/Users/Models/UserUpdateRequest.cs
@@ -2,6 +2,6 @@ namespace TableauSharp.Users.Models;
 
 public class UserUpdateRequest
 {
-    public string SiteRole { get; set; }
+    public string SiteRole { get; set; } = string.Empty;
     public bool IsActive { get; set; }
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Users/Services/GroupService.cs b/src/TableauSharp/Users/Services/GroupService.cs
index 0330b7e..c871bb2 100644
--- a/src/TableauSharp/Users/Services/GroupService.cs
+++ b/src/TableauSharp/Users/Services/GroupService.cs
@@ -31,8 +31,8 @@ public async Task<IEnumerable<TableauGroup>> GetAllAsync(CancellationToken cance
         {
             groups.Add(new TableauGroup
             {
-                Id = g.GetProperty("id").GetString(),
-                Name = g.GetProperty("name").GetString()
+                Id = g.GetProperty("id").GetString() ?? string.Empty,
+                Name = g.GetProperty("name").GetString() ?? string.Empty
             });
         }
 
@@ -52,8 +52,8 @@ public async Task<TableauGroup> GetByIdAsync(string groupId, CancellationToken c
 
         return new TableauGroup
         {
-            Id = g.GetProperty("id").GetString(),
-            Name = g.GetProperty("name").GetString()
+            Id = g.GetProperty("id").GetString() ?? string.Empty,
+            Name = g.GetProperty("name").GetString() ?? string.Empty
         };
     }
 
@@ -74,8 +74,8 @@ public async Task<TableauGroup> CreateAsync(GroupCreateRequest request, Cancella
 
         return new TableauGroup
         {
-            Id = g.GetProperty("id").GetString(),
-            Name = g.GetProperty("name").GetString()
+            Id = g.GetProperty("id").GetString() ?? string.Empty,
+            Name = g.GetProperty("name").GetString() ?? string.Empty
         };
     }
 
diff --git a/src/TableauSharp/Users/Services/UserService.cs b/src/TableauSharp/Users/Services/UserService.cs
index 2d7bae5..5b5074c 100644
--- a/src/TableauSharp/Users/Services/UserService.cs
+++ b/src/TableauSharp/Users/Services/UserService.cs
@@ -31,10 +31,10 @@ public async Task<IEnumerable<TableauUser>> GetAllAsync(CancellationToken cancel
         {
             users.Add(new TableauUser
             {
-                Id = u.GetProperty("id").GetString(),
-                Name = u.GetProperty("name").GetString(),
-                Email = u.GetProperty("email").GetString(),
-                SiteRole = u.GetProperty("siteRole").GetString()
+                Id = u.GetProperty("id").GetString() ?? string.Empty,
+                Name = u.GetProperty("name").GetString() ?? string.Empty,
+                Email = u.TryGetProperty("email", out var email) ? email.GetString() : null,
+                SiteRole = u.GetProperty("siteRole").GetString() ?? string.Empty
             });
         }
 
@@ -54,10 +54,10 @@ public async Task<TableauUser> GetByIdAsync(string userId, CancellationToken can
 
         return new TableauUser
         {
-            Id = u.GetProperty("id").GetString(),
-            Name = u.GetProperty("name").GetString(),
-            Email = u.GetProperty("email").GetString(),
-            SiteRole = u.GetProperty("siteRole").GetString()
+            Id = u.GetProperty("id").GetString() ?? string.Empty,
+            Name = u.GetProperty("name").GetString() ?? string.Empty,
+            Email = u.TryGetProperty("email", out var email) ? email.GetString() : null,
+            SiteRole = u.GetProperty("siteRole").GetString() ?? string.Empty
         };
     }
 
@@ -78,10 +78,10 @@ public async Task<TableauUser> CreateAsync(UserCreateRequest request, Cancellati
 
         return new TableauUser
         {
-            Id = u.GetProperty("id").GetString(),
-            Name = u.GetProperty("name").GetString(),
-            Email = u.GetProperty("email").GetString(),
-            SiteRole = u.GetProperty("siteRole").GetString()
+            Id = u.GetProperty("id").GetString() ?? string.Empty,
+            Name = u.GetProperty("name").GetString() ?? string.Empty,
+            Email = u.TryGetProperty("email", out var email) ? email.GetString() : null,
+            SiteRole = u.GetProperty("siteRole").GetString() ?? string.Empty
         };
     }
 
@@ -102,10 +102,10 @@ public async Task<TableauUser> UpdateAsync(string userId, UserUpdateRequest requ
 
         return new TableauUser
         {
-            Id = u.GetProperty("id").GetString(),
-            Name = u.GetProperty("name").GetString(),
-            Email = u.GetProperty("email").GetString(),
-            SiteRole = u.GetProperty("siteRole").GetString()
+            Id = u.GetProperty("id").GetString() ?? string.Empty,
+            Name = u.GetProperty("name").GetString() ?? string.Empty,
+            Email = u.TryGetProperty("email", out var email) ? email.GetString() : null,
+            SiteRole = u.GetProperty("siteRole").GetString() ?? string.Empty
         };
     }
 
diff --git a/src/TableauSharp/Workbooks/Models/ExportRequest.cs b/src/TableauSharp/Workbooks/Models/ExportRequest.cs
index 3e8dce7..1b394df 100644
--- a/src/TableauSharp/Workbooks/Models/ExportRequest.cs
+++ b/src/TableauSharp/Workbooks/Models/ExportRequest.cs
@@ -2,9 +2,9 @@ namespace TableauSharp.Workbooks.Models;
 
 public class ExportRequest
 {
-    public string WorkbookId { get; set; }
-    public string ViewId { get; set; }
-    public string Format { get; set; } // "PDF", "PNG", "CSV"
+    public string? WorkbookId { get; set; }
+    public string ViewId { get; set; } = string.Empty;
+    public string Format { get; set; } = string.Empty; // "PDF", "PNG", "CSV"
     public int? MaxWidth { get; set; }
     public int? MaxHeight { get; set; }
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Workbooks/Models/ExportResponse.cs b/src/TableauSharp/Workbooks/Models/ExportResponse.cs
index 3d6bd2f..60f2411 100644
--- a/src/TableauSharp/Workbooks/Models/ExportResponse.cs
+++ b/src/TableauSharp/Workbooks/Models/ExportResponse.cs
@@ -2,7 +2,7 @@ namespace TableauSharp.Workbooks.Models;
 
 public class ExportResponse
 {
-    public byte[] FileContent { get; set; }
-    public string ContentType { get; set; }
-    public string FileName { get; set; }
-}
\ No newline at end of file
+    public byte[] FileContent { get; set; } = [];
+    public string ContentType { get; set; } = string.Empty;
+    public string FileName { get; set; } = string.Empty;
+}
diff --git a/src/TableauSharp/Workbooks/Models/TableauView.cs b/src/TableauSharp/Workbooks/Models/TableauView.cs
index b4e1cd7..f4115bb 100644
--- a/src/TableauSharp/Workbooks/Models/TableauView.cs
+++ b/src/TableauSharp/Workbooks/Models/TableauView.cs
@@ -5,23 +5,23 @@ namespace TableauSharp.Workbooks.Models;
 public class TableauView
 {
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = string.Empty;
 
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = string.Empty;
 
     [JsonPropertyName("contentUrl")]
-    public string ContentUrl { get; set; }
+    public string ContentUrl { get; set; } = string.Empty;
 
     [JsonPropertyName("workbookId")]
-    public string WorkbookId { get; set; }
+    public string WorkbookId { get; set; } = string.Empty;
 
     [JsonPropertyName("ownerId")]
-    public string OwnerId { get; set; }
+    public string? OwnerId { get; set; }
 
     [JsonPropertyName("totalViews")]
     public int TotalViews { get; set; }
 
     [JsonPropertyName("lastViewedAt")]
-    public DateTime LastViewedAt { get; set; }
-}
\ No newline at end of file
+    public DateTime? LastViewedAt { get; set; }
+}
diff --git a/src/TableauSharp/Workbooks/Models/TableauWorkbook.cs b/src/TableauSharp/Workbooks/Models/TableauWorkbook.cs
index bd2ea6f..3274089 100644
--- a/src/TableauSharp/Workbooks/Models/TableauWorkbook.cs
+++ b/src/TableauSharp/Workbooks/Models/TableauWorkbook.cs
@@ -5,16 +5,16 @@ namespace TableauSharp.Workbooks.Models;
 public class TableauWorkbook
 {
     [JsonPropertyName("id")]
-    public string Id { get; set; }
+    public string Id { get; set; } = string.Empty;
 
     [JsonPropertyName("name")]
-    public string Name { get; set; }
+    public string Name { get; set; } = string.Empty;
 
     [JsonPropertyName("projectId")]
-    public string ProjectId { get; set; }
+    public string ProjectId { get; set; } = string.Empty;
 
     [JsonPropertyName("ownerId")]
-    public string OwnerId { get; set; }
+    public string? OwnerId { get; set; }
 
     [JsonPropertyName("createdAt")]
     public DateTime CreatedAt { get; set; }
@@ -24,4 +24,4 @@ public class TableauWorkbook
 
     [JsonPropertyName("views")]
     public List<TableauView> Views { get; set; } = new();
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Workbooks/Models/WorkbookPublishRequest.cs b/src/TableauSharp/Workbooks/Models/WorkbookPublishRequest.cs
index aabd7a1..5a39972 100644
--- a/src/TableauSharp/Workbooks/Models/WorkbookPublishRequest.cs
+++ b/src/TableauSharp/Workbooks/Models/WorkbookPublishRequest.cs
@@ -2,8 +2,8 @@ namespace TableauSharp.Workbooks.Models;
 
 public class WorkbookPublishRequest
 {
-    public string Name { get; set; }
-    public string ProjectId { get; set; }
-    public string FilePath { get; set; }
+    public string Name { get; set; } = string.Empty;
+    public string ProjectId { get; set; } = string.Empty;
+    public string FilePath { get; set; } = string.Empty;
     public bool Overwrite { get; set; }
-}
\ No newline at end of file
+}
diff --git a/src/TableauSharp/Workbooks/Services/ViewService.cs b/src/TableauSharp/Workbooks/Services/ViewService.cs
index 6f12c6d..0ab466a 100644
--- a/src/TableauSharp/Workbooks/Services/ViewService.cs
+++ b/src/TableauSharp/Workbooks/Services/ViewService.cs
@@ -33,14 +33,14 @@ public async Task<IEnumerable<TableauView>> GetViewsByWorkbookIdAsync(string wor
         {
             views.Add(new TableauView
             {
-                Id = v.GetProperty("id").GetString(),
-                Name = v.GetProperty("name").GetString(),
-                ContentUrl = v.GetProperty("contentUrl").GetString(),
+                Id = v.GetProperty("id").GetString() ?? string.Empty,
+                Name = v.GetProperty("name").GetString() ?? string.Empty,
+                ContentUrl = v.GetProperty("contentUrl").GetString() ?? string.Empty,
                 WorkbookId = workbookId,
                 TotalViews = v.GetProperty("totalViews").GetInt32(),
                 LastViewedAt = v.TryGetProperty("lastViewedAt", out var lastViewed)
                     ? lastViewed.GetDateTime()
-                    : default
+                    : null
             });
 
         }
diff --git a/src/TableauSharp/Workbooks/Services/WorkbookService.cs b/src/TableauSharp/Workbooks/Services/WorkbookService.cs
index 6cfb602..c26a5e1 100644
--- a/src/TableauSharp/Workbooks/Services/WorkbookService.cs
+++ b/src/TableauSharp/Workbooks/Services/WorkbookService.cs
@@ -32,9 +32,9 @@ public async Task<IEnumerable<TableauWorkbook>> GetAllAsync(CancellationToken ca
         {
             workbooks.Add(new TableauWorkbook
             {
-                Id = w.GetProperty("id").GetString(),
-                Name = w.GetProperty("name").GetString(),
-                ProjectId = w.GetProperty("project").GetProperty("id").GetString(),
+                Id = w.GetProperty("id").GetString() ?? string.Empty,
+                Name = w.GetProperty("name").GetString() ?? string.Empty,
+                ProjectId = w.GetProperty("project").GetProperty("id").GetString() ?? string.Empty,
                 OwnerId = w.GetProperty("owner").GetProperty("id").GetString(),
                 CreatedAt = w.GetProperty("createdAt").GetDateTime(),
                 UpdatedAt = w.GetProperty("updatedAt").GetDateTime()
@@ -58,9 +58,9 @@ public async Task<TableauWorkbook> GetByIdAsync(string workbookId, CancellationT
 
         return new TableauWorkbook
         {
-            Id = w.GetProperty("id").GetString(),
-            Name = w.GetProperty("name").GetString(),
-            ProjectId = w.GetProperty("project").GetProperty("id").GetString(),
+            Id = w.GetProperty("id").GetString() ?? string.Empty,
+            Name = w.GetProperty("name").GetString() ?? string.Empty,
+            ProjectId = w.GetProperty("project").GetProperty("id").GetString() ?? string.Empty,
             OwnerId = w.GetProperty("owner").GetProperty("id").GetString(),
             CreatedAt = w.GetProperty("createdAt").GetDateTime(),
             UpdatedAt = w.GetProperty("updatedAt").GetDateTime()
@@ -92,9 +92,9 @@ public async Task<TableauWorkbook> PublishAsync(WorkbookPublishRequest request,
 
         return new TableauWorkbook
         {
-            Id = w.GetProperty("id").GetString(),
-            Name = w.GetProperty("name").GetString(),
-            ProjectId = w.GetProperty("project").GetProperty("id").GetString(),
+            Id = w.GetProperty("id").GetString() ?? string.Empty,
+            Name = w.GetProperty("name").GetString() ?? string.Empty,
+            ProjectId = w.GetProperty("project").GetProperty("id").GetString() ?? string.Empty,
             OwnerId = w.GetProperty("owner").GetProperty("id").GetString(),
             CreatedAt = w.GetProperty("createdAt").GetDateTime(),
             UpdatedAt = w.GetProperty("updatedAt").GetDateTime()
diff --git a/test/TableauSharp.Tests/Projects/ProjectServiceTests.cs b/test/TableauSharp.Tests/Projects/ProjectServiceTests.cs
index d103d3c..e4de118 100644
--- a/test/TableauSharp.Tests/Projects/ProjectServiceTests.cs
+++ b/test/TableauSharp.Tests/Projects/ProjectServiceTests.cs
@@ -37,6 +37,22 @@ public async Task GetAllAsync_UsesSignedInSiteIdAndAuthHeader()
         });
     }
 
+    [Test]
+    public async Task GetAllAsync_WhenOptionalFieldsAreMissing_ReturnsNullOptionalValues()
+    {
+        _context.MockHttp.When(HttpMethod.Get, $"{_context.SiteBase}projects")
+            .Respond("application/json", ProjectWithoutOptionalFieldsJson);
+
+        var result = (await _service.GetAllAsync()).Single();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(result.Id, Is.EqualTo("proj-002"));
+            Assert.That(result.Description, Is.Null);
+            Assert.That(result.ParentProjectId, Is.Null);
+        });
+    }
+
     [Test]
     public async Task UpdateAsync_UsesSignedInSiteIdAndAuthHeader()
     {
@@ -76,4 +92,16 @@ public async Task UpdateAsync_UsesSignedInSiteIdAndAuthHeader()
           }
         }
         """;
+
+    private static string ProjectWithoutOptionalFieldsJson => """
+        {
+          "projects": [
+            {
+              "id": "proj-002",
+              "name": "No optional fields",
+              "owner": { "id": "user-001" }
+            }
+          ]
+        }
+        """;
 }
diff --git a/test/TableauSharp.Tests/Users/UserServiceTests.cs b/test/TableauSharp.Tests/Users/UserServiceTests.cs
index c44a8db..47a5305 100644
--- a/test/TableauSharp.Tests/Users/UserServiceTests.cs
+++ b/test/TableauSharp.Tests/Users/UserServiceTests.cs
@@ -37,6 +37,21 @@ public async Task GetAllAsync_UsesSignedInSiteIdAndAuthHeader()
         });
     }
 
+    [Test]
+    public async Task GetAllAsync_WhenEmailIsMissing_ReturnsNullEmail()
+    {
+        _context.MockHttp.When(HttpMethod.Get, $"{_context.SiteBase}users")
+            .Respond("application/json", UserWithoutEmailJson);
+
+        var result = (await _service.GetAllAsync()).Single();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(result.Id, Is.EqualTo("user-002"));
+            Assert.That(result.Email, Is.Null);
+        });
+    }
+
     [Test]
     public async Task UpdateAsync_UsesSignedInSiteIdAndAuthHeader()
     {
@@ -72,4 +87,16 @@ public async Task UpdateAsync_UsesSignedInSiteIdAndAuthHeader()
           }
         }
         """;
+
+    private static string UserWithoutEmailJson => """
+        {
+          "users": [
+            {
+              "id": "user-002",
+              "name": "bob",
+              "siteRole": "Viewer"
+            }
+          ]
+        }
+        """;
 }
diff --git a/test/TableauSharp.Tests/Workbooks/ViewServiceTests.cs b/test/TableauSharp.Tests/Workbooks/ViewServiceTests.cs
index ab6e504..1f84604 100644
--- a/test/TableauSharp.Tests/Workbooks/ViewServiceTests.cs
+++ b/test/TableauSharp.Tests/Workbooks/ViewServiceTests.cs
@@ -105,6 +105,21 @@ public async Task ExportViewAsync_ReturnsFileContentFromSignedInSite()
         });
     }
 
+    [Test]
+    public async Task GetViewsByWorkbookIdAsync_WhenLastViewedAtIsMissing_ReturnsNullLastViewedAt()
+    {
+        _mockHttp.When(HttpMethod.Get, $"{SiteBase}workbooks/wb-001/views")
+            .Respond("application/json", ViewWithoutLastViewedAtJson);
+
+        var result = (await _service.GetViewsByWorkbookIdAsync("wb-001")).Single();
+
+        Assert.Multiple(() =>
+        {
+            Assert.That(result.Id, Is.EqualTo("view-002"));
+            Assert.That(result.LastViewedAt, Is.Null);
+        });
+    }
+
     [Test]
     public void GetViewsByWorkbookIdAsync_WhenCancellationRequested_ThrowsTaskCanceledException()
     {
@@ -130,4 +145,17 @@ public void GetViewsByWorkbookIdAsync_WhenCancellationRequested_ThrowsTaskCancel
           ]
         }
         """;
+
+    private static string ViewWithoutLastViewedAtJson => """
+        {
+          "views": [
+            {
+              "id": "view-002",
+              "name": "Inventory View",
+              "contentUrl": "inventory-view",
+              "totalViews": 0
+            }
+          ]
+        }
+        """;
 }