diff --git a/Cargo.lock b/Cargo.lock
index 1378fb9..c5af46c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2714,6 +2714,7 @@ dependencies = [
  "itertools",
  "log",
  "parking_lot",
+ "rand 0.8.3",
  "serde",
  "serde_json",
  "thiserror",
diff --git a/yopa-web/src/routes/models/object.rs b/yopa-web/src/routes/models/object.rs
index 361257b..d80669c 100644
--- a/yopa-web/src/routes/models/object.rs
+++ b/yopa-web/src/routes/models/object.rs
@@ -41,7 +41,7 @@ pub(crate) struct ObjectModelForm {
     pub name: String,
     #[serde(default)]
     // #[serde(with="serde_with::rust::default_on_error")] // This is because "" can be selected
-    #[serde(with="my_string_empty_as_none")]
+    #[serde(with = "my_string_empty_as_none")]
     pub name_property: Option<ID>,
 }
 
@@ -56,7 +56,7 @@ pub(crate) async fn create(
     match wg.define_object(ObjectModel {
         id: Default::default(),
         name: form.name.clone(),
-        name_property: form.name_property
+        name_property: form.name_property,
     }) {
         Ok(_id) => {
             wg.persist().err_to_500()?;
@@ -96,10 +96,13 @@ pub(crate) async fn update_form(
         context.insert("model", &model);
     } else {
         context.insert("model", model);
-        context.insert("old", &ObjectModelForm {
-            name: model.name.to_string(),
-            name_property: model.name_property
-        });
+        context.insert(
+            "old",
+            &ObjectModelForm {
+                name: model.name.to_string(),
+                name_property: model.name_property,
+            },
+        );
     }
 
     let properties = rg.get_property_models_for_parent(*model_id).collect_vec();
@@ -162,30 +165,29 @@ pub(crate) async fn delete(
     }
 }
 
-
 pub mod my_string_empty_as_none {
-    use serde::{Deserializer, Serializer, Serialize};
-    use std::str::FromStr;
-    use std::fmt::{Display, Write};
-    use std::marker::PhantomData;
-    use serde::de::{Visitor, Error};
+    use serde::de::{Error, Visitor};
+    use serde::{Deserializer, Serialize, Serializer};
     use std::fmt;
+    use std::fmt::Display;
+    use std::marker::PhantomData;
+    use std::str::FromStr;
     use yopa::ID;
 
     // FIXME largely copied from serde_with
 
     /// Deserialize an `Option<T>` from a string using `FromStr`
     pub fn deserialize<'de, D, S>(deserializer: D) -> Result<Option<S>, D::Error>
-        where
-            D: Deserializer<'de>,
-            S: FromStr,
-            S::Err: Display,
+    where
+        D: Deserializer<'de>,
+        S: FromStr,
+        S::Err: Display,
     {
         struct OptionStringEmptyNone<S>(PhantomData<S>);
         impl<'de, S> Visitor<'de> for OptionStringEmptyNone<S>
-            where
-                S: FromStr,
-                S::Err: Display,
+        where
+            S: FromStr,
+            S::Err: Display,
         {
             type Value = Option<S>;
 
@@ -194,8 +196,8 @@ pub mod my_string_empty_as_none {
             }
 
             fn visit_str<E>(self, value: &str) -> Result<Self::Value, E>
-                where
-                    E: Error,
+            where
+                E: Error,
             {
                 match value {
                     "" => Ok(None),
@@ -204,8 +206,8 @@ pub mod my_string_empty_as_none {
             }
 
             fn visit_string<E>(self, value: String) -> Result<Self::Value, E>
-                where
-                    E: Error,
+            where
+                E: Error,
             {
                 match &*value {
                     "" => Ok(None),
@@ -215,16 +217,16 @@ pub mod my_string_empty_as_none {
 
             // TODO remove?
             fn visit_u64<E>(self, v: u64) -> Result<Self::Value, E>
-                where
-                    E: Error,
+            where
+                E: Error,
             {
                 self.visit_str(&v.to_string())
             }
 
             // handles the `null` case
             fn visit_unit<E>(self) -> Result<Self::Value, E>
-                where
-                    E: Error,
+            where
+                E: Error,
             {
                 Ok(None)
             }
@@ -235,8 +237,8 @@ pub mod my_string_empty_as_none {
 
     /// Serialize a string from `Option<T>` using `AsRef<str>` or using the empty string if `None`.
     pub fn serialize<S>(option: &Option<ID>, serializer: S) -> Result<S::Ok, S::Error>
-        where
-            S: Serializer,
+    where
+        S: Serializer,
     {
         option.serialize(serializer)
 
diff --git a/yopa-web/src/routes/objects.rs b/yopa-web/src/routes/objects.rs
index 1aafeb3..adcb7c6 100644
--- a/yopa-web/src/routes/objects.rs
+++ b/yopa-web/src/routes/objects.rs
@@ -1,23 +1,24 @@
-use std::borrow::{Borrow, Cow};
+use std::borrow::Cow;
 use std::collections::HashMap;
 
 use actix_session::Session;
-use actix_web::{HttpResponse, Responder, web};
+use actix_web::{web, HttpResponse, Responder};
 use heck::TitleCase;
 use itertools::Itertools;
 use json_dotpath::DotPaths;
 use serde::Serialize;
 
-use yopa::{data, ID, model, Storage};
-use yopa::data::Object;
+use yopa::{data, model, Storage, ID};
+
 use yopa::insert::InsertObj;
 use yopa::model::{ObjectModel, PropertyModel, RelationModel};
 use yopa::update::UpdateObj;
 
 use crate::session_ext::SessionExt;
-use crate::TERA;
 use crate::tera_ext::TeraExt;
 use crate::utils::{redirect, StorageErrorIntoResponseError};
+use crate::TERA;
+use yopa::helpers::GroupByModel;
 
 // we only need references here, Context serializes everything to Value.
 // cloning would be a waste of cycles
@@ -97,13 +98,14 @@ fn prepare_object_create_data(rg: &Storage, model_id: ID) -> actix_web::Result<O
                 .get_property_models_for_parents(prop_object_ids)
                 .collect(),
         },
-        objects: rg.get_objects_of_types(related_ids).map(|o| {
-            ObjectDisplay {
+        objects: rg
+            .get_objects_of_types(related_ids)
+            .map(|o| ObjectDisplay {
                 id: o.id,
                 model: o.model,
                 name: rg.get_object_name(o),
-            }
-        }).collect(),
+            })
+            .collect(),
     })
 }
 
@@ -162,13 +164,16 @@ pub(crate) async fn list_inner(
         .sorted_by_key(|m| &m.name)
         .map(|model| {
             let objects = objects_by_model.remove(&model.id).unwrap_or_default();
-            let mut objects = objects.into_iter().map(|o| {
-                ObjectDisplay {
-                    id: o.id,
-                    model: o.model,
-                    name: rg.get_object_name(o), // TODO optimize
-                }
-            }).collect_vec();
+            let mut objects = objects
+                .into_iter()
+                .map(|o| {
+                    ObjectDisplay {
+                        id: o.id,
+                        model: o.model,
+                        name: rg.get_object_name(o), // TODO optimize
+                    }
+                })
+                .collect_vec();
 
             objects.sort_by(|a, b| a.name.cmp(&b.name));
             ModelWithObjects { model, objects }
@@ -223,11 +228,14 @@ pub(crate) async fn detail(
         .get_object_model(object.model)
         .ok_or_else(|| actix_web::error::ErrorNotFound("No such model"))?;
 
-    context.insert("object", &ObjectDisplay {
-        id: object_id,
-        model: object.model,
-        name: rg.get_object_name(object),
-    });
+    context.insert(
+        "object",
+        &ObjectDisplay {
+            id: object_id,
+            model: object.model,
+            name: rg.get_object_name(object),
+        },
+    );
     context.insert("model", model);
     context.insert("kind", &rg.get_model_name(object.model));
 
@@ -248,8 +256,7 @@ pub(crate) async fn detail(
         let object_values_by_model = grouped_values
             .remove(&object_id)
             .unwrap_or_default()
-            .into_iter()
-            .into_group_map_by(|value| value.model);
+            .group_by_model();
 
         let mut view_object_properties = vec![];
         for (prop_model_id, values) in object_values_by_model {
@@ -268,7 +275,7 @@ pub(crate) async fn detail(
     {
         let grouped_relations = relations
             .iter()
-            .into_group_map_by(|relation| relation.model);
+            .group_by_model();
 
         let mut relation_views = vec![];
         for (model_id, relations) in grouped_relations {
@@ -283,8 +290,7 @@ pub(crate) async fn detail(
                 let rel_values_by_model = grouped_values
                     .remove(&rel.id)
                     .unwrap_or_default()
-                    .into_iter()
-                    .into_group_map_by(|value| value.model);
+                    .group_by_model();
 
                 let mut view_rel_properties = vec![];
                 for (prop_model_id, values) in rel_values_by_model {
@@ -327,7 +333,7 @@ pub(crate) async fn detail(
     {
         let grouped_relations = reci_relations
             .iter()
-            .into_group_map_by(|relation| relation.model);
+            .group_by_model();
 
         let mut relation_views = vec![];
         for (model_id, relations) in grouped_relations {
@@ -342,8 +348,7 @@ pub(crate) async fn detail(
                 let rel_values_by_model = grouped_values
                     .remove(&rel.id)
                     .unwrap_or_default()
-                    .into_iter()
-                    .into_group_map_by(|value| value.model);
+                    .group_by_model();
 
                 let mut view_rel_properties = vec![];
                 for (prop_model_id, values) in rel_values_by_model {
@@ -428,11 +433,14 @@ pub(crate) async fn update_form(
 
     // maybe its useful,idk
     context.insert("model", &model);
-    context.insert("object", &ObjectDisplay {
-        id: object.id,
-        model: object.model,
-        name: rg.get_object_name(object),
-    });
+    context.insert(
+        "object",
+        &ObjectDisplay {
+            id: object.id,
+            model: object.model,
+            name: rg.get_object_name(object),
+        },
+    );
 
     let create_data = prepare_object_create_data(&rg, model.id)?;
 
@@ -448,7 +456,8 @@ pub(crate) async fn update_form(
         .map(|p| p.id)
         .collect_vec();
 
-    let mut values_grouped = rg.get_values_for_object(*id).into_group_map_by(|v| v.model);
+    let mut values_grouped = rg.get_values_for_object(*id)
+        .group_by_model();
 
     prop_ids.into_iter().for_each(|id| {
         value_map.insert(
@@ -472,7 +481,7 @@ pub(crate) async fn update_form(
 
         let mut relations_grouped_by_model = relations
             .iter()
-            .into_group_map_by(|relation| relation.model);
+            .group_by_model();
 
         let mut property_models_grouped_by_parent =
             rg.get_grouped_prop_models_for_parents(relation_model_ids.clone());
@@ -497,8 +506,7 @@ pub(crate) async fn update_form(
                 let mut rel_values = relation_values_grouped_by_instance
                     .remove(&rel.id)
                     .unwrap_or_default()
-                    .into_iter()
-                    .into_group_map_by(|relation| relation.model);
+                    .group_by_model();
 
                 prop_models_for_relation.iter().for_each(|prop_model| {
                     relation_values_map.insert(
@@ -525,7 +533,7 @@ pub(crate) async fn update_form(
     let object = EnrichedObject {
         id: object.id,
         model: object.model,
-        name: rg.get_object_name_by_id(object.id),
+        name: rg.get_object_name(object),
         values: value_map,
         relations: relation_map,
     };
@@ -558,7 +566,11 @@ pub(crate) async fn update(
         Ok(_id) => {
             wg.persist().err_to_500()?;
             debug!("Object created, redirecting to root");
-            session.flash_success(format!("{} \"{}\" updated.", model_name, wg.get_object_name_by_id(id)));
+            session.flash_success(format!(
+                "{} \"{}\" updated.",
+                model_name,
+                wg.get_object_name_by_id(id)
+            ));
             Ok(HttpResponse::Ok().finish())
         }
         Err(e) => {
diff --git a/yopa/Cargo.toml b/yopa/Cargo.toml
index f546121..cc686f5 100644
--- a/yopa/Cargo.toml
+++ b/yopa/Cargo.toml
@@ -22,6 +22,7 @@ itertools = "0.10.0"
 #lazy_static = "1.4.0"
 bincode = "1.3.1"
 atomic = "0.5.0"
+rand = "0.8.3"
 
 [features]
 default = []
diff --git a/yopa/src/cool.rs b/yopa/src/cool.rs
index f7af889..ba0f32c 100644
--- a/yopa/src/cool.rs
+++ b/yopa/src/cool.rs
@@ -40,18 +40,16 @@ impl<K, V> KVVecToKeysOrValues<K, V> for Vec<(K, V)> {
     }
 }
 
-pub(crate) trait IsNoneOrElse<T> : Sized {
+pub(crate) trait IsNoneOrElse<T>: Sized {
     //noinspection RsSelfConvention
-    fn is_none_or_else(&self, test : impl FnOnce(&T) -> bool) -> bool;
+    fn is_none_or_else(&self, test: impl FnOnce(&T) -> bool) -> bool;
 }
 
 impl<T> IsNoneOrElse<T> for Option<T> {
     fn is_none_or_else(&self, test: impl FnOnce(&T) -> bool) -> bool {
         match self {
             None => true,
-            Some(value) => {
-                test(value)
-            }
+            Some(value) => test(value),
         }
     }
 }
diff --git a/yopa/src/data.rs b/yopa/src/data.rs
index b9e2cd5..1c57cf4 100644
--- a/yopa/src/data.rs
+++ b/yopa/src/data.rs
@@ -1,6 +1,6 @@
 //! Data value structs
 
-use std::borrow::{Cow, Borrow};
+use std::borrow::{Borrow, Cow};
 
 use serde::{Deserialize, Serialize};
 
diff --git a/yopa/src/helpers.rs b/yopa/src/helpers.rs
new file mode 100644
index 0000000..0289084
--- /dev/null
+++ b/yopa/src/helpers.rs
@@ -0,0 +1,200 @@
+//! Helper traits and stuff for working with lists and iterators of objects
+
+// Re-export itertools for convenience
+pub use itertools;
+
+use crate::{data, insert, model, update, ID};
+
+use itertools::Itertools;
+use std::collections::HashMap;
+
+pub trait GetParent {
+    fn get_parent(&self) -> ID;
+}
+
+macro_rules! impl_get_parent {
+    ($($struct:ty),+) => {
+        $(
+            impl GetParent for $struct {
+                fn get_parent(&self) -> ID { self.object }
+            }
+            impl GetParent for &$struct {
+                fn get_parent(&self) -> ID { self.object }
+            }
+            impl GetParent for &&$struct {
+                fn get_parent(&self) -> ID { self.object }
+            }
+        )+
+    }
+}
+
+impl_get_parent!(
+    data::Value, data::Relation,
+    model::RelationModel, model::PropertyModel);
+
+pub trait GetModelID {
+    fn get_model_id(&self) -> ID;
+}
+
+macro_rules! impl_get_model_id {
+    ($($struct:ty),+) => {
+        $(
+            impl GetModelID for $struct {
+                fn get_model_id(&self) -> ID { self.model }
+            }
+            impl GetModelID for &$struct {
+                fn get_model_id(&self) -> ID { self.model }
+            }
+            impl GetModelID for &&$struct {
+                fn get_model_id(&self) -> ID { self.model }
+            }
+        )+
+    }
+}
+
+impl_get_model_id!(
+    data::Object, data::Value, data::Relation,
+    insert::InsertRel, insert::InsertValue, insert::InsertObj,
+    update::UpsertRelation, update::UpsertValue);
+
+// This would be nice, but doesn't work
+
+//
+// pub struct FilterOfParent<'a, S: 'a> { iter: S, parent: ID, marker : std::marker::PhantomData<&'a S> }
+//
+// // impl<'a, V: GetParent + 'a, S: Iterator<Item=&'a V>> Iterator for FilterOfParent<S> {
+// //     type Item = &'a V;
+// //
+// //     #[inline]
+// //     fn next(&mut self) -> Option<Self::Item> {
+// //         let parent = self.parent;
+// //         self.iter.find(|x| x.get_parent() == parent)
+// //     }
+// // }
+//
+// impl<'a, V: GetParent + 'a, S: Iterator<Item=V>> Iterator for FilterOfParent<'a, S> {
+//     type Item = V;
+//
+//     #[inline]
+//     fn next(&mut self) -> Option<Self::Item> {
+//         let parent = self.parent;
+//         self.iter.find(|x| x.get_parent() == parent)
+//     }
+// }
+//
+// pub trait WhereParent<'a>: Sized {
+//     fn where_parent(self, id: ID) -> FilterOfParent<'a, Self>;
+// }
+//
+// impl<'a, V : 'a, S : 'a + Iterator<Item=V>> WhereParent<'a> for S {
+//     fn where_parent(self, id: ID) -> FilterOfParent<'a, Self> {
+//         FilterOfParent { iter: self, parent: id, marker: std::marker::PhantomData }
+//     }
+// }
+
+pub trait GroupByParent<'a, T: 'a + GetParent>: Sized {
+    fn group_by_parent(self) -> HashMap<ID, Vec<T>>;
+}
+
+impl<'a, T: 'a + GetParent, S: IntoIterator<Item = T>> GroupByParent<'a, T> for S {
+    #[inline]
+    fn group_by_parent(self) -> HashMap<ID, Vec<T>> {
+        self.into_iter().into_group_map_by(|v| v.get_parent())
+    }
+}
+
+pub trait GroupByModel<'a, T: 'a + GetModelID>: Sized {
+    fn group_by_model(self) -> HashMap<ID, Vec<T>>;
+}
+
+impl<'a, T: 'a + GetModelID, S: IntoIterator<Item = T>> GroupByModel<'a, T> for S {
+    #[inline]
+    fn group_by_model(self) -> HashMap<ID, Vec<T>> {
+        self.into_iter().into_group_map_by(|v| v.get_model_id())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::helpers::{GetParent, GroupByParent};
+    use crate::id::random_id;
+    use crate::ID;
+
+    #[derive(Debug, PartialEq, Eq)]
+    struct Child(ID, &'static str);
+
+    impl GetParent for Child {
+        fn get_parent(&self) -> ID {
+            self.0
+        }
+    }
+
+    #[test]
+    fn group_vec() {
+        let parent1 = random_id();
+        let parent2 = random_id();
+
+        let vec = vec![
+            Child(parent1, "A"),
+            Child(parent2, "C"),
+            Child(parent1, "B"),
+            Child(parent2, "D"),
+        ];
+
+        let mut grouped = vec.group_by_parent();
+
+        assert_eq!(2, grouped.len());
+
+        assert_eq!(
+            grouped.remove(&parent1).unwrap(),
+            vec![Child(parent1, "A"), Child(parent1, "B"),]
+        );
+
+        assert_eq!(
+            grouped.remove(&parent2).unwrap(),
+            vec![Child(parent2, "C"), Child(parent2, "D"),]
+        );
+    }
+
+    #[test]
+    fn group_iter() {
+        let parent1 = random_id();
+        let parent2 = random_id();
+
+        let vec = vec![
+            Child(parent1, "A"),
+            Child(parent2, "C"),
+            Child(parent1, "B"),
+            Child(parent2, "D"),
+        ];
+
+        let mut grouped = vec.into_iter().group_by_parent();
+
+        assert_eq!(2, grouped.len());
+
+        assert_eq!(
+            grouped.remove(&parent1).unwrap(),
+            vec![Child(parent1, "A"), Child(parent1, "B"),]
+        );
+
+        assert_eq!(
+            grouped.remove(&parent2).unwrap(),
+            vec![Child(parent2, "C"), Child(parent2, "D"),]
+        );
+    }
+
+    // #[test]
+    // fn count_where_parent() {
+    //     let parent1 = random_id();
+    //     let parent2 = random_id();
+    //
+    //     let vec = vec![
+    //         Child(parent1, "A"),
+    //         Child(parent2, "C"),
+    //         Child(parent1, "B"),
+    //         Child(parent2, "D"),
+    //     ];
+    //
+    //     let _ = vec.iter().where_parent(parent2).next();
+    // }
+}
diff --git a/yopa/src/id.rs b/yopa/src/id.rs
index b405727..0a3a2f7 100644
--- a/yopa/src/id.rs
+++ b/yopa/src/id.rs
@@ -17,3 +17,16 @@ pub type ID = u32;
 pub trait HaveId {
     fn get_id(&self) -> ID;
 }
+
+#[cfg(feature = "uuid-ids")]
+#[cfg(test)]
+pub fn random_id() -> ID {
+    ID::new_v4()
+}
+
+#[cfg(not(feature = "uuid-ids"))]
+#[cfg(test)]
+pub fn random_id() -> ID {
+    use rand::Rng;
+    rand::thread_rng().gen()
+}
diff --git a/yopa/src/insert.rs b/yopa/src/insert.rs
index 5c08bc3..097c85a 100644
--- a/yopa/src/insert.rs
+++ b/yopa/src/insert.rs
@@ -48,11 +48,7 @@ pub struct InsertObj {
 }
 
 impl InsertObj {
-    pub fn new(
-        model_id: ID,
-        values: Vec<InsertValue>,
-        relations: Vec<InsertRel>,
-    ) -> Self {
+    pub fn new(model_id: ID, values: Vec<InsertValue>, relations: Vec<InsertRel>) -> Self {
         Self {
             model: model_id,
             values,
diff --git a/yopa/src/lib.rs b/yopa/src/lib.rs
index 70abd26..46b9696 100644
--- a/yopa/src/lib.rs
+++ b/yopa/src/lib.rs
@@ -1,7 +1,8 @@
 #[macro_use]
 extern crate log;
-// #[macro_use]
-// extern crate serde_json;
+#[cfg(test)]
+#[macro_use]
+extern crate serde_json;
 
 use std::borrow::Cow;
 use std::collections::HashMap;
@@ -21,10 +22,11 @@ use insert::InsertValue;
 pub use model::DataType;
 use model::ObjectModel;
 
+use crate::cool::IsNoneOrElse;
+use crate::data::Object;
+use crate::helpers::{GroupByModel, GroupByParent};
 use crate::model::{PropertyModel, RelationModel};
 use crate::update::{UpdateObj, UpsertValue};
-use crate::cool::IsNoneOrElse;
-use crate::data::{Object, Value};
 
 mod cool;
 pub mod data;
@@ -33,6 +35,8 @@ pub mod insert;
 pub mod model;
 pub mod update;
 
+pub mod helpers;
+
 mod serde_atomic_id;
 mod serde_map_as_list;
 #[cfg(test)]
@@ -40,8 +44,8 @@ mod tests;
 
 pub const VERSION: &'static str = env!("CARGO_PKG_VERSION");
 
-pub const YOPA_MAGIC : &[u8; 4] = b"YOPA";
-pub const BINARY_FORMAT : u8 = 1;
+pub const YOPA_MAGIC: &[u8; 4] = b"YOPA";
+pub const BINARY_FORMAT: u8 = 1;
 
 /// Stupid storage with naive inefficient file persistence
 #[derive(Debug, Default, Serialize, Deserialize)]
@@ -62,7 +66,7 @@ pub struct Storage {
 
     #[cfg(not(feature = "uuid-ids"))]
     #[serde(with = "serde_atomic_id")]
-    next_id : atomic::Atomic<ID>,
+    next_id: atomic::Atomic<ID>,
 
     #[serde(skip)]
     opts: StoreOpts,
@@ -180,7 +184,7 @@ impl Storage {
                 let parsed: Self = match self.opts.file_format {
                     FileEncoding::JSON => serde_json::from_reader(reader)?,
                     FileEncoding::BINCODE => {
-                        let mut magic : [u8; 5] = [0; 5];
+                        let mut magic: [u8; 5] = [0; 5];
                         reader.read_exact(&mut magic)?;
 
                         if &magic[0..4] != YOPA_MAGIC {
@@ -193,7 +197,7 @@ impl Storage {
                         }
 
                         bincode::deserialize_from(reader)?
-                    },
+                    }
                 };
 
                 let opts = std::mem::replace(&mut self.opts, StoreOpts::default());
@@ -231,7 +235,7 @@ impl Storage {
                         writer.write_all(YOPA_MAGIC)?;
                         writer.write_all(&[BINARY_FORMAT])?;
                         bincode::serialize_into(writer, self)?
-                    },
+                    }
                 };
             }
         }
@@ -253,7 +257,7 @@ impl Storage {
     }
 
     /// Get object name, or the ID as string if no name is configured
-    pub fn get_object_name_by_id<'a>(&'a self, id : ID) -> Cow<'a, str> {
+    pub fn get_object_name_by_id<'a>(&'a self, id: ID) -> Cow<'a, str> {
         if let Some(o) = self.get_object(id) {
             return self.get_object_name(o);
         }
@@ -261,9 +265,17 @@ impl Storage {
         return id.to_string().into();
     }
 
-    pub fn get_object_name<'b, 'a: 'b>(&'a self, object : &'a Object) -> Cow<'b, str> {
-        if let Some(ObjectModel{ name_property: Some(name_property), .. }) = self.get_object_model(object.model) {
-            if let Some(v) = self.values.values().find(|v| v.object == object.id && &v.model == name_property) {
+    pub fn get_object_name<'b, 'a: 'b>(&'a self, object: &'a Object) -> Cow<'b, str> {
+        if let Some(ObjectModel {
+            name_property: Some(name_property),
+            ..
+        }) = self.get_object_model(object.model)
+        {
+            if let Some(v) = self
+                .values
+                .values()
+                .find(|v| v.object == object.id && &v.model == name_property)
+            {
                 return v.value.to_cow();
             }
         }
@@ -293,7 +305,9 @@ impl Storage {
 
     /// Iterate object models with given IDs
     pub fn get_object_models_by_ids(&self, ids: Vec<ID>) -> impl Iterator<Item = &ObjectModel> {
-        self.obj_models.values().filter(move |m| ids.contains(&m.id))
+        self.obj_models
+            .values()
+            .filter(move |m| ids.contains(&m.id))
     }
 
     /// Get an object model by ID
@@ -313,9 +327,7 @@ impl Storage {
 
     /// Get all property models grouped by the parent object ID.
     pub fn get_grouped_prop_models(&self) -> HashMap<ID, Vec<&PropertyModel>> {
-        self.prop_models
-            .values()
-            .into_group_map_by(|model| model.object)
+        self.prop_models.values().group_by_parent()
     }
 
     /// Get property models belonging to a group of parent IDs,
@@ -327,7 +339,7 @@ impl Storage {
         self.prop_models
             .values()
             .filter(|p| parent_model_ids.contains(&p.object))
-            .into_group_map_by(|model| model.object)
+            .group_by_parent()
     }
 
     /// Iterate relation models attached to an object model
@@ -362,9 +374,7 @@ impl Storage {
 
     /// Get all relation models, grouped by their source object model ID
     pub fn get_grouped_relation_models(&self) -> HashMap<ID, Vec<&RelationModel>> {
-        self.rel_models
-            .values()
-            .into_group_map_by(|model| model.object)
+        self.rel_models.values().group_by_parent()
     }
 
     /// Get reciprocal relation models, grouped by their destination model ID
@@ -411,7 +421,7 @@ impl Storage {
         self.values
             .values()
             .filter(move |prop| parents.contains(&prop.object))
-            .into_group_map_by(|model| model.object)
+            .group_by_parent()
     }
 
     /// Get all objects belonging to a model.
@@ -432,9 +442,7 @@ impl Storage {
 
     /// Get all objects, grouped by their model ID
     pub fn get_grouped_objects(&self) -> HashMap<ID, Vec<&data::Object>> {
-        self.objects
-            .values()
-            .into_group_map_by(|object| object.model)
+        self.objects.values().group_by_model()
     }
 
     /// Get object by ID
@@ -830,7 +838,7 @@ impl Storage {
                                      parent_id: ID,
                                      parent_model_id: ID|
          -> Result<Vec<data::Value>, StorageError> {
-            let mut values_by_id = values.into_iter().into_group_map_by(|iv| iv.model);
+            let mut values_by_id = values.group_by_model();
             let mut values_to_insert = vec![];
 
             for (prop_model_id, prop) in self
@@ -873,7 +881,7 @@ impl Storage {
                                     first.value,
                                     self.get_model_name(*prop_model_id),
                                 )
-                                    .into(),
+                                .into(),
                             ));
                         }
                     }
@@ -908,10 +916,7 @@ impl Storage {
         let mut values_to_insert = find_values_to_insert(insobj.values, object_id, obj_model_id)?;
 
         // And now ..... relations!
-        let mut relations_by_id = insobj
-            .relations
-            .into_iter()
-            .into_group_map_by(|ir| ir.model);
+        let mut relations_by_id = insobj.relations.group_by_model();
         let mut relations_to_insert = vec![];
 
         for (relation_model_id, relation_model) in self
@@ -1020,7 +1025,7 @@ impl Storage {
             ),
             StorageError,
         > {
-            let mut values_by_model = values.into_iter().into_group_map_by(|iv| iv.model);
+            let mut values_by_model = values.group_by_model();
             let mut values_to_insert = vec![];
             let mut ids_to_delete = vec![];
 
@@ -1028,7 +1033,7 @@ impl Storage {
                 .values
                 .values()
                 .filter(|v| v.object == parent_id)
-                .into_group_map_by(|v| v.model);
+                .group_by_model();
 
             for (prop_model_id, prop) in self
                 .prop_models
@@ -1071,7 +1076,7 @@ impl Storage {
                                     first.value,
                                     self.get_model_name(*prop_model_id),
                                 )
-                                    .into(),
+                                .into(),
                             ));
                         }
                     }
@@ -1113,10 +1118,7 @@ impl Storage {
             find_values_to_change(updobj.values, updated_object_id, updated_object_model_id)?;
 
         // And now ..... relations!
-        let mut relations_by_model = updobj
-            .relations
-            .into_iter()
-            .into_group_map_by(|ir| ir.model);
+        let mut relations_by_model = updobj.relations.group_by_model();
         let mut relations_to_insert = vec![];
         let mut relations_to_delete = vec![];
 
@@ -1124,7 +1126,7 @@ impl Storage {
             .relations
             .values()
             .filter(|v| v.object == updated_object_id)
-            .into_group_map_by(|v| v.model);
+            .group_by_model();
 
         let rel_models_by_id = self
             .rel_models
@@ -1196,8 +1198,6 @@ impl Storage {
             );
         }
 
-        let obj_mut = self.objects.get_mut(&updated_object_id).unwrap();
-
         debug!("Add {} new object relations", relations_to_insert.len());
         for rel in relations_to_insert {
             self.relations.insert(rel.id, rel);
diff --git a/yopa/src/serde_atomic_id.rs b/yopa/src/serde_atomic_id.rs
index 94c5ef8..9a7f673 100644
--- a/yopa/src/serde_atomic_id.rs
+++ b/yopa/src/serde_atomic_id.rs
@@ -1,20 +1,19 @@
 //! Serialize atomic ID by fetching its value
 
 use crate::id::ID;
-use serde::{Serialize, Deserializer, Deserialize};
+use serde::{Deserialize, Deserializer, Serialize};
 
 pub fn serialize<S>(x: &atomic::Atomic<ID>, s: S) -> Result<S::Ok, S::Error>
 where
     S: serde::Serializer,
 {
-    x.load(atomic::Ordering::Relaxed)
-        .serialize(s)
+    x.load(atomic::Ordering::Relaxed).serialize(s)
 }
 
 pub fn deserialize<'de, D>(deserializer: D) -> Result<atomic::Atomic<ID>, D::Error>
 where
-    D: Deserializer<'de>
+    D: Deserializer<'de>,
 {
-    let id : ID = ID::deserialize(deserializer)?;
+    let id: ID = ID::deserialize(deserializer)?;
     Ok(atomic::Atomic::new(id))
 }
diff --git a/yopa/src/tests.rs b/yopa/src/tests.rs
index a93a54c..970be0f 100644
--- a/yopa/src/tests.rs
+++ b/yopa/src/tests.rs
@@ -5,6 +5,7 @@ fn test1() {
     let model = crate::model::ObjectModel {
         id: Default::default(),
         name: "Name".to_string(),
+        name_property: None,
     };
 
     println!("{}", serde_json::to_string_pretty(&model).unwrap());