Changed the struct to make things launch. I've done no testing.

app/src/components/create_user.rs

@@ -86,7 +86,7 @@ impl CommonComponent<CreateUserForm> for CreateUserForm {
                     user: create_user::CreateUserInput {
                         id: model.username,
                         email: model.email,
-                        displayName: to_option(model.display_name),
+                        displayName: model.display_name,
                         firstName: to_option(model.first_name),
                         lastName: to_option(model.last_name),
                         avatar: None,

app/src/components/user_details_form.rs

@@ -355,7 +355,7 @@ impl UserDetailsForm {
         let mut user_input = update_user::UpdateUserInput {
             id: self.common.user.id.clone(),
             email: None,
-            displayName: None,
+            displayName: self.common.user.id.clone(),
             firstName: None,
             lastName: None,
             avatar: None,
@@ -367,7 +367,7 @@ impl UserDetailsForm {
             user_input.email = Some(email);
         }
         if base_user.display_name != model.display_name {
-            user_input.displayName = Some(model.display_name);
+            user_input.displayName = model.display_name;
         }
         if base_user.first_name != model.first_name {
             user_input.firstName = Some(model.first_name);

schema.graphql

@@ -57,7 +57,7 @@ type Query {
 input CreateUserInput {
   id: String!
   email: String!
-  displayName: String
+  displayName: String!
   firstName: String
   lastName: String
   avatar: String
@@ -84,7 +84,7 @@ type Success {
 input UpdateUserInput {
   id: String!
   email: String
-  displayName: String
+  displayName: String!
   firstName: String
   lastName: String
   avatar: String

server/src/domain/handler.rs

@@ -1,7 +1,8 @@
 use super::{
     error::Result,
     types::{
-        Group, GroupDetails, GroupId, JpegPhoto, User, UserAndGroups, UserColumn, UserId, Uuid,
+        DisplayName, Group, GroupDetails, GroupId, JpegPhoto, User, UserAndGroups, UserColumn,
+        UserId, Uuid,
     },
 };
 use async_trait::async_trait;
@@ -44,7 +45,7 @@ pub struct CreateUserRequest {
     // Same fields as User, but no creation_date, and with password.
     pub user_id: UserId,
     pub email: String,
-    pub display_name: Option<String>,
+    pub display_name: DisplayName,
     pub first_name: Option<String>,
     pub last_name: Option<String>,
     pub avatar: Option<JpegPhoto>,
@@ -55,7 +56,7 @@ pub struct UpdateUserRequest {
     // Same fields as CreateUserRequest, but no with an extra layer of Option.
     pub user_id: UserId,
     pub email: Option<String>,
-    pub display_name: Option<String>,
+    pub display_name: DisplayName,
     pub first_name: Option<String>,
     pub last_name: Option<String>,
     pub avatar: Option<JpegPhoto>,

server/src/domain/ldap/user.rs

@@ -48,7 +48,7 @@ fn get_user_attribute(
                 .into_bytes()
             })
             .collect(),
-        "cn" | "displayname" => vec![user.display_name.clone()?.into_bytes()],
+        "cn" | "displayname" => vec![user.display_name.to_string().into_bytes()],
         "createtimestamp" | "modifytimestamp" => vec![user.creation_date.to_rfc3339().into_bytes()],
         "1.1" => return None,
         // We ignore the operational attribute wildcard.

server/src/domain/model/users.rs

@@ -3,7 +3,7 @@
 use sea_orm::entity::prelude::*;
 use serde::{Deserialize, Serialize};
 
-use crate::domain::types::{JpegPhoto, UserId, Uuid};
+use crate::domain::types::{DisplayName, JpegPhoto, UserId, Uuid};
 
 #[derive(Copy, Clone, Default, Debug, DeriveEntity)]
 pub struct Entity;
@@ -14,7 +14,7 @@ pub struct Model {
     #[sea_orm(primary_key, auto_increment = false)]
     pub user_id: UserId,
     pub email: String,
-    pub display_name: Option<String>,
+    pub display_name: DisplayName,
     pub first_name: Option<String>,
     pub last_name: Option<String>,
     pub avatar: Option<JpegPhoto>,

server/src/domain/sql_backend_handler.rs

@@ -26,7 +26,7 @@ pub mod tests {
                 CreateUserRequest, GroupBackendHandler, UserBackendHandler, UserRequestFilter,
             },
             sql_tables::init_table,
-            types::{GroupId, UserId},
+            types::{DisplayName, GroupId, UserId},
         },
         infra::configuration::ConfigurationBuilder,
     };
@@ -86,7 +86,7 @@ pub mod tests {
             .create_user(CreateUserRequest {
                 user_id: UserId::new(name),
                 email: "bob@bob.bob".to_string(),
-                display_name: Some("display ".to_string() + name),
+                display_name: DisplayName::new(("display ".to_owned() + name).as_str()),
                 first_name: Some("first ".to_string() + name),
                 last_name: Some("last ".to_string() + name),
                 ..Default::default()

server/src/domain/sql_user_backend_handler.rs

@@ -163,7 +163,7 @@ impl UserBackendHandler for SqlBackendHandler {
         let new_user = model::users::ActiveModel {
             user_id: Set(request.user_id),
             email: Set(request.email),
-            display_name: to_value(&request.display_name),
+            display_name: ActiveValue::Set(request.display_name),
             first_name: to_value(&request.first_name),
             last_name: to_value(&request.last_name),
             avatar: request.avatar.into_active_value(),
@@ -181,7 +181,7 @@ impl UserBackendHandler for SqlBackendHandler {
         let update_user = model::users::ActiveModel {
             user_id: ActiveValue::Set(request.user_id),
             email: request.email.map(ActiveValue::Set).unwrap_or_default(),
-            display_name: to_value(&request.display_name),
+            display_name: ActiveValue::Set(request.display_name),
             first_name: to_value(&request.first_name),
             last_name: to_value(&request.last_name),
             avatar: request.avatar.into_active_value(),
@@ -238,7 +238,7 @@ mod tests {
     use super::*;
     use crate::domain::{
         sql_backend_handler::tests::*,
-        types::{JpegPhoto, UserColumn},
+        types::{DisplayName, JpegPhoto, UserColumn},
     };
 
     #[tokio::test]
@@ -407,11 +407,7 @@ mod tests {
             .map(|u| {
                 (
                     u.user.user_id.to_string(),
-                    u.user
+                    u.user.display_name.to_string(),
-                        .display_name
-                        .as_deref()
-                        .unwrap_or("<unknown>")
-                        .to_owned(),
                     u.groups
                         .unwrap_or_default()
                         .into_iter()
@@ -567,7 +563,7 @@ mod tests {
             .update_user(UpdateUserRequest {
                 user_id: UserId::new("bob"),
                 email: Some("email".to_string()),
-                display_name: Some("display_name".to_string()),
+                display_name: DisplayName::new("display_name"),
                 first_name: Some("first_name".to_string()),
                 last_name: Some("last_name".to_string()),
                 avatar: Some(JpegPhoto::for_tests()),
@@ -581,7 +577,7 @@ mod tests {
             .await
             .unwrap();
         assert_eq!(user.email, "email");
-        assert_eq!(user.display_name.unwrap(), "display_name");
+        assert_eq!(user.display_name.as_str(), "display_name");
         assert_eq!(user.first_name.unwrap(), "first_name");
         assert_eq!(user.last_name.unwrap(), "last_name");
         assert_eq!(user.avatar, Some(JpegPhoto::for_tests()));
@@ -607,7 +603,7 @@ mod tests {
             .get_user_details(&UserId::new("bob"))
             .await
             .unwrap();
-        assert_eq!(user.display_name.unwrap(), "display bob");
+        assert_eq!(user.display_name.as_str(), "display bob");
         assert_eq!(user.first_name.unwrap(), "first_name");
         assert_eq!(user.last_name, None);
         assert_eq!(user.avatar, None);

server/src/domain/types.rs

@@ -167,6 +167,82 @@ impl ValueType for UserId {
     }
 }
 
+#[derive(PartialEq, Eq, Clone, Debug, Default, Serialize, Deserialize)]
+#[serde(from = "String")]
+pub struct DisplayName(String);
+
+impl DisplayName {
+    pub fn new(display_name: &str) -> Self {
+        Self(display_name.to_string())
+    }
+
+    pub fn as_str(&self) -> &str {
+        self.0.as_str()
+    }
+
+    pub fn into_string(self) -> String {
+        self.0
+    }
+}
+
+impl std::fmt::Display for DisplayName {
+    fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+impl From<String> for DisplayName {
+    fn from(s: String) -> Self {
+        Self::new(&s)
+    }
+}
+
+impl From<DisplayName> for Value {
+    fn from(display_name: DisplayName) -> Self {
+        display_name.into_string().into()
+    }
+}
+
+impl From<&DisplayName> for Value {
+    fn from(display_name: &DisplayName) -> Self {
+        display_name.as_str().into()
+    }
+}
+
+impl TryGetable for DisplayName {
+    fn try_get(res: &QueryResult, pre: &str, col: &str) -> Result<Self, TryGetError> {
+        Ok(DisplayName::new(&String::try_get(res, pre, col)?))
+    }
+}
+
+impl TryFromU64 for DisplayName {
+    fn try_from_u64(_n: u64) -> Result<Self, DbErr> {
+        Err(DbErr::ConvertFromU64(
+            "DisplayName cannot be constructed from u64",
+        ))
+    }
+}
+
+impl ValueType for DisplayName {
+    fn try_from(v: Value) -> Result<Self, ValueTypeErr> {
+        Ok(DisplayName::new(
+            <String as ValueType>::try_from(v)?.as_str(),
+        ))
+    }
+
+    fn type_name() -> String {
+        "DisplayName".to_owned()
+    }
+
+    fn array_type() -> ArrayType {
+        ArrayType::String
+    }
+
+    fn column_type() -> ColumnType {
+        ColumnType::String(Some(255))
+    }
+}
+
 #[derive(PartialEq, Eq, Clone, Debug, Serialize, Deserialize)]
 pub struct JpegPhoto(#[serde(with = "serde_bytes")] Vec<u8>);
 
@@ -304,7 +380,7 @@ impl IntoActiveValue<JpegPhoto> for JpegPhoto {
 pub struct User {
     pub user_id: UserId,
     pub email: String,
-    pub display_name: Option<String>,
+    pub display_name: DisplayName,
     pub first_name: Option<String>,
     pub last_name: Option<String>,
     pub avatar: Option<JpegPhoto>,
@@ -320,7 +396,7 @@ impl Default for User {
         User {
             user_id: UserId::default(),
             email: String::new(),
-            display_name: None,
+            display_name: DisplayName::default(),
             first_name: None,
             last_name: None,
             avatar: None,

server/src/infra/auth_service.rs

@@ -171,9 +171,7 @@ where
         Some(token) => token,
     };
     if let Err(e) = super::mail::send_password_reset_email(
-        user.display_name
+        user.display_name.as_str(),
-            .as_deref()
-            .unwrap_or_else(|| user.user_id.as_str()),
         &user.email,
         &token,
         &data.server_url,

server/src/infra/graphql/mutation.rs

@@ -1,6 +1,6 @@
 use crate::domain::{
     handler::{BackendHandler, CreateUserRequest, UpdateGroupRequest, UpdateUserRequest},
-    types::{GroupId, JpegPhoto, UserId},
+    types::{DisplayName, GroupId, JpegPhoto, UserId},
 };
 use anyhow::Context as AnyhowContext;
 use juniper::{graphql_object, FieldResult, GraphQLInputObject, GraphQLObject};
@@ -27,7 +27,7 @@ impl<Handler: BackendHandler> Mutation<Handler> {
 pub struct CreateUserInput {
     id: String,
     email: String,
-    display_name: Option<String>,
+    display_name: String,
     first_name: Option<String>,
     last_name: Option<String>,
     // Base64 encoded JpegPhoto.
@@ -39,7 +39,7 @@ pub struct CreateUserInput {
 pub struct UpdateUserInput {
     id: String,
     email: Option<String>,
-    display_name: Option<String>,
+    display_name: String,
     first_name: Option<String>,
     last_name: Option<String>,
     // Base64 encoded JpegPhoto.
@@ -79,6 +79,7 @@ impl<Handler: BackendHandler + Sync> Mutation<Handler> {
             return Err("Unauthorized user creation".into());
         }
         let user_id = UserId::new(&user.id);
+        let display_name = DisplayName::new(&user.display_name);
         let avatar = user
             .avatar
             .map(base64::decode)
@@ -92,7 +93,7 @@ impl<Handler: BackendHandler + Sync> Mutation<Handler> {
             .create_user(CreateUserRequest {
                 user_id: user_id.clone(),
                 email: user.email,
-                display_name: user.display_name,
+                display_name: display_name.clone(),
                 first_name: user.first_name,
                 last_name: user.last_name,
                 avatar,
@@ -137,6 +138,7 @@ impl<Handler: BackendHandler + Sync> Mutation<Handler> {
             debug!(?user.id);
         });
         let user_id = UserId::new(&user.id);
+        let display_name = DisplayName::new(&user.display_name);
         if !context.validation_result.can_write(&user_id) {
             span.in_scope(|| debug!("Unauthorized"));
             return Err("Unauthorized user update".into());
@@ -154,7 +156,7 @@ impl<Handler: BackendHandler + Sync> Mutation<Handler> {
             .update_user(UpdateUserRequest {
                 user_id,
                 email: user.email,
-                display_name: user.display_name,
+                display_name: display_name.clone(),
                 first_name: user.first_name,
                 last_name: user.last_name,
                 avatar,

server/src/infra/graphql/query.rs

@@ -214,7 +214,7 @@ impl<Handler: BackendHandler + Sync> User<Handler> {
     }
 
     fn display_name(&self) -> &str {
-        self.user.display_name.as_deref().unwrap_or("")
+        self.user.display_name.as_str()
     }
 
     fn first_name(&self) -> &str {

server/src/infra/ldap_handler.rs

@@ -10,7 +10,7 @@ use crate::{
             },
         },
         opaque_handler::OpaqueHandler,
-        types::{JpegPhoto, UserId},
+        types::{DisplayName, JpegPhoto, UserId},
     },
     infra::auth_service::{Permission, ValidationResults},
 };
@@ -460,6 +460,8 @@ impl<Backend: BackendHandler + LoginHandler + OpaqueHandler> LdapHandler<Backend
             &self.ldap_info.base_dn,
             &self.ldap_info.base_dn_str,
         )?;
+
+        //
         fn parse_attribute(mut attr: LdapPartialAttribute) -> LdapResult<(String, Vec<u8>)> {
             if attr.vals.len() > 1 {
                 Err(LdapError {
@@ -506,7 +508,12 @@ impl<Backend: BackendHandler + LoginHandler + OpaqueHandler> LdapHandler<Backend
                     .or_else(|| get_attribute("email"))
                     .transpose()?
                     .unwrap_or_default(),
-                display_name: get_attribute("cn").transpose()?,
+                display_name: DisplayName::new(
+                    get_attribute("cn")
+                        .transpose()?
+                        .unwrap_or_default()
+                        .as_str(),
+                ),
                 first_name: get_attribute("givenname").transpose()?,
                 last_name: get_attribute("sn").transpose()?,
                 avatar: attributes
@@ -989,7 +996,7 @@ mod tests {
                     user: User {
                         user_id: UserId::new("bob_1"),
                         email: "bob@bobmail.bob".to_string(),
-                        display_name: Some("Bôb Böbberson".to_string()),
+                        display_name: DisplayName::new("Bôb Böbberson"),
                         first_name: Some("Bôb".to_string()),
                         last_name: Some("Böbberson".to_string()),
                         uuid: uuid!("698e1d5f-7a40-3151-8745-b9b8a37839da"),
@@ -1001,7 +1008,7 @@ mod tests {
                     user: User {
                         user_id: UserId::new("jim"),
                         email: "jim@cricket.jim".to_string(),
-                        display_name: Some("Jimminy Cricket".to_string()),
+                        display_name: DisplayName::new("Jimminy Cricket"),
                         first_name: Some("Jim".to_string()),
                         last_name: Some("Cricket".to_string()),
                         avatar: Some(JpegPhoto::for_tests()),
@@ -1540,7 +1547,7 @@ mod tests {
                 user: User {
                     user_id: UserId::new("bob_1"),
                     email: "bob@bobmail.bob".to_string(),
-                    display_name: Some("Bôb Böbberson".to_string()),
+                    display_name: DisplayName::new("Bôb Böbberson"),
                     first_name: Some("Bôb".to_string()),
                     last_name: Some("Böbberson".to_string()),
                     ..Default::default()
@@ -1614,7 +1621,7 @@ mod tests {
                 user: User {
                     user_id: UserId::new("bob_1"),
                     email: "bob@bobmail.bob".to_string(),
-                    display_name: Some("Bôb Böbberson".to_string()),
+                    display_name: DisplayName::new("Bôb Böbberson"),
                     last_name: Some("Böbberson".to_string()),
                     avatar: Some(JpegPhoto::for_tests()),
                     uuid: uuid!("b4ac75e0-2900-3e21-926c-2f732c26b3fc"),
@@ -2041,7 +2048,7 @@ mod tests {
             .with(eq(CreateUserRequest {
                 user_id: UserId::new("bob"),
                 email: "".to_owned(),
-                display_name: Some("Bob".to_string()),
+                display_name: DisplayName::new("Bob"),
                 ..Default::default()
             }))
             .times(1)

server/src/main.rs

@@ -9,6 +9,7 @@ use crate::{
         handler::{CreateUserRequest, GroupBackendHandler, GroupRequestFilter, UserBackendHandler},
         sql_backend_handler::SqlBackendHandler,
         sql_opaque_handler::register_password,
+        types::DisplayName,
     },
     infra::{cli::*, configuration::Configuration, db_cleaner::Scheduler, healthcheck, mail},
 };
@@ -33,7 +34,7 @@ async fn create_admin_user(handler: &SqlBackendHandler, config: &Configuration)
         .create_user(CreateUserRequest {
             user_id: config.ldap_user_dn.clone(),
             email: config.ldap_user_email.clone(),
-            display_name: Some("Administrator".to_string()),
+            display_name: DisplayName::new("Administrator"),
             ..Default::default()
         })
         .and_then(|_| register_password(handler, &config.ldap_user_dn, &config.ldap_user_pass))