diff --git a/patch-db-macro-internals/src/lib.rs b/patch-db-macro-internals/src/lib.rs
index e46c86c..7465f10 100644
--- a/patch-db-macro-internals/src/lib.rs
+++ b/patch-db-macro-internals/src/lib.rs
@@ -162,6 +162,11 @@ fn build_model_struct(
                             #model_name(#inner_model::from(ptr))
                         }
                     }
+                    impl AsRef<patch_db::json_ptr::JsonPointer> for #model_name {
+                        fn as_ref(&self) -> &patch_db::json_ptr::JsonPointer {
+                            self.0.as_ref()
+                        }
+                    }
                     impl From<patch_db::Model<#base_name>> for #model_name {
                         fn from(model: patch_db::Model<#base_name>) -> Self {
                             #model_name(#inner_model::from(patch_db::json_ptr::JsonPointer::from(model)))
@@ -237,6 +242,11 @@ fn build_model_struct(
                 #model_name(From::from(ptr))
             }
         }
+        impl AsRef<patch_db::json_ptr::JsonPointer> for #model_name {
+            fn as_ref(&self) -> &patch_db::json_ptr::JsonPointer {
+                self.0.as_ref()
+            }
+        }
         impl From<patch_db::Model<#base_name>> for #model_name {
             fn from(model: patch_db::Model<#base_name>) -> Self {
                 #model_name(model)
@@ -248,11 +258,41 @@ fn build_model_struct(
     }
 }
 
-fn build_model_enum(base: &DeriveInput, ast: &DataEnum, model_name: Option<Ident>) -> TokenStream {
-    todo!(
-        "use {:?}, {:?} and {:?} to create a model that can become an enum of models",
-        base,
-        ast,
-        model_name
-    )
+fn build_model_enum(base: &DeriveInput, _: &DataEnum, model_name: Option<Ident>) -> TokenStream {
+    let model_name = model_name.unwrap_or_else(|| {
+        Ident::new(
+            &format!("{}Model", base.ident),
+            proc_macro2::Span::call_site(),
+        )
+    });
+    let base_name = &base.ident;
+    let model_vis = &base.vis;
+    quote! {
+        #[derive(Debug, Clone)]
+        #model_vis struct #model_name(patch_db::Model<#base_name>);
+        impl core::ops::Deref for #model_name {
+            type Target = patch_db::Model<#base_name>;
+            fn deref(&self) -> &Self::Target {
+                &self.0
+            }
+        }
+        impl From<patch_db::json_ptr::JsonPointer> for #model_name {
+            fn from(ptr: patch_db::json_ptr::JsonPointer) -> Self {
+                #model_name(From::from(ptr))
+            }
+        }
+        impl AsRef<patch_db::json_ptr::JsonPointer> for #model_name {
+            fn as_ref(&self) -> &patch_db::json_ptr::JsonPointer {
+                self.0.as_ref()
+            }
+        }
+        impl From<patch_db::Model<#base_name>> for #model_name {
+            fn from(model: patch_db::Model<#base_name>) -> Self {
+                #model_name(model)
+            }
+        }
+        impl patch_db::HasModel for #base_name {
+            type Model = #model_name;
+        }
+    }
 }
diff --git a/patch-db/src/lib.rs b/patch-db/src/lib.rs
index 4ca0282..3411861 100644
--- a/patch-db/src/lib.rs
+++ b/patch-db/src/lib.rs
@@ -15,13 +15,15 @@ mod transaction;
 #[cfg(test)]
 mod test;
 
+pub use json_ptr;
 pub use locker::{LockType, Locker};
-pub use model::{BoxModel, HasModel, MapModel, Model, ModelData, ModelDataMut, VecModel};
+pub use model::{
+    BoxModel, HasModel, MapModel, Model, ModelData, ModelDataMut, OptionModel, VecModel,
+};
 pub use patch::Revision;
 pub use patch_db_macro::HasModel;
 pub use store::{PatchDb, Store};
 pub use transaction::{Checkpoint, SubTransaction, Transaction};
-pub use json_ptr;
 
 #[derive(Error, Debug)]
 pub enum Error {
diff --git a/patch-db/src/model.rs b/patch-db/src/model.rs
index a112a85..5943c2f 100644
--- a/patch-db/src/model.rs
+++ b/patch-db/src/model.rs
@@ -95,6 +95,14 @@ where
         }
     }
 }
+impl<T> AsRef<JsonPointer> for Model<T>
+where
+    T: Serialize + for<'de> Deserialize<'de>,
+{
+    fn as_ref(&self) -> &JsonPointer {
+        &self.ptr
+    }
+}
 impl<T> From<Model<T>> for JsonPointer
 where
     T: Serialize + for<'de> Deserialize<'de>,
@@ -116,9 +124,10 @@ where
 }
 
 pub trait HasModel {
-    type Model: From<JsonPointer>;
+    type Model: From<JsonPointer> + AsRef<JsonPointer>;
 }
 
+#[derive(Debug, Clone)]
 pub struct BoxModel<T: HasModel + Serialize + for<'de> Deserialize<'de>>(T::Model);
 impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> Deref for BoxModel<T> {
     type Target = T::Model;
@@ -131,6 +140,14 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> From<Model<Box<T>>> fo
         BoxModel(T::Model::from(JsonPointer::from(model)))
     }
 }
+impl<T> AsRef<JsonPointer> for BoxModel<T>
+where
+    T: HasModel + Serialize + for<'de> Deserialize<'de>,
+{
+    fn as_ref(&self) -> &JsonPointer {
+        self.0.as_ref()
+    }
+}
 impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> From<JsonPointer> for BoxModel<T> {
     fn from(ptr: JsonPointer) -> Self {
         BoxModel(T::Model::from(ptr))
@@ -140,6 +157,34 @@ impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> HasModel for Box<T> {
     type Model = BoxModel<T>;
 }
 
+#[derive(Debug, Clone)]
+pub struct OptionModel<T: HasModel + Serialize + for<'de> Deserialize<'de>>(T::Model);
+impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> OptionModel<T> {
+    pub async fn check<Tx: Checkpoint>(self, tx: &mut Tx) -> Result<Option<T::Model>, Error> {
+        Ok(if tx.exists(self.0.as_ref(), None).await? {
+            Some(self.0)
+        } else {
+            None
+        })
+    }
+}
+impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> From<Model<Option<T>>>
+    for OptionModel<T>
+{
+    fn from(model: Model<Option<T>>) -> Self {
+        OptionModel(T::Model::from(JsonPointer::from(model)))
+    }
+}
+impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> From<JsonPointer> for OptionModel<T> {
+    fn from(ptr: JsonPointer) -> Self {
+        OptionModel(T::Model::from(ptr))
+    }
+}
+impl<T: HasModel + Serialize + for<'de> Deserialize<'de>> HasModel for Option<T> {
+    type Model = BoxModel<T>;
+}
+
+#[derive(Debug, Clone)]
 pub struct VecModel<T: Serialize + for<'de> Deserialize<'de>>(Model<Vec<T>>);
 impl<T: Serialize + for<'de> Deserialize<'de>> Deref for VecModel<T> {
     type Target = Model<Vec<T>>;
@@ -152,8 +197,8 @@ impl<T: Serialize + for<'de> Deserialize<'de>> VecModel<T> {
         self.child(&format!("{}", idx))
     }
 }
-impl<T: Serialize + for<'de> Deserialize<'de>> From<Model<Box<T>>> for VecModel<T> {
-    fn from(model: Model<Box<T>>) -> Self {
+impl<T: Serialize + for<'de> Deserialize<'de>> From<Model<Vec<T>>> for VecModel<T> {
+    fn from(model: Model<Vec<T>>) -> Self {
         VecModel(From::from(JsonPointer::from(model)))
     }
 }
@@ -162,10 +207,19 @@ impl<T: Serialize + for<'de> Deserialize<'de>> From<JsonPointer> for VecModel<T>
         VecModel(From::from(ptr))
     }
 }
+impl<T> AsRef<JsonPointer> for VecModel<T>
+where
+    T: Serialize + for<'de> Deserialize<'de>,
+{
+    fn as_ref(&self) -> &JsonPointer {
+        self.0.as_ref()
+    }
+}
 impl<T: Serialize + for<'de> Deserialize<'de>> HasModel for Vec<T> {
     type Model = VecModel<T>;
 }
 
+#[derive(Debug, Clone)]
 pub struct MapModel<T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>>(Model<T>);
 impl<T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>> Deref for MapModel<T> {
     type Target = Model<T>;
@@ -182,6 +236,15 @@ where
         self.child(idx)
     }
 }
+impl<T> MapModel<T>
+where
+    T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>,
+    for<'a, 'de> <T as Index<&'a str>>::Output: Serialize + Deserialize<'de> + HasModel,
+{
+    pub fn idx_model(&self, idx: &str) -> OptionModel<<T as Index<&str>>::Output> {
+        self.child(idx).into()
+    }
+}
 impl<T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>> From<Model<Box<T>>>
     for MapModel<T>
 {
@@ -196,6 +259,14 @@ impl<T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>> From<Jso
         MapModel(From::from(ptr))
     }
 }
+impl<T> AsRef<JsonPointer> for MapModel<T>
+where
+    T: Serialize + for<'de> Deserialize<'de> + for<'a> Index<&'a str>,
+{
+    fn as_ref(&self) -> &JsonPointer {
+        self.0.as_ref()
+    }
+}
 impl<K, V> HasModel for HashMap<K, V>
 where
     K: Serialize + for<'de> Deserialize<'de> + Hash + Eq,
diff --git a/patch-db/src/patch.rs b/patch-db/src/patch.rs
index 7f488aa..b9d46a0 100644
--- a/patch-db/src/patch.rs
+++ b/patch-db/src/patch.rs
@@ -77,6 +77,7 @@ impl DiffPatch {
                 .collect(),
         ))
     }
+
     pub fn rebase(&mut self, onto: &DiffPatch) {
         let DiffPatch(Patch(ops)) = self;
         let DiffPatch(Patch(onto_ops)) = onto;
@@ -148,6 +149,31 @@ impl DiffPatch {
             }
         }
     }
+
+    pub fn exists(&self) -> Option<bool> {
+        let mut res = None;
+        for op in &(self.0).0 {
+            match op {
+                PatchOperation::Add(a) => {
+                    if a.path.is_empty() {
+                        res = Some(!a.value.is_null());
+                    }
+                }
+                PatchOperation::Replace(a) => {
+                    if a.path.is_empty() {
+                        res = Some(!a.value.is_null())
+                    }
+                }
+                PatchOperation::Remove(a) => {
+                    if a.path.is_empty() {
+                        res = Some(false)
+                    }
+                }
+                _ => unreachable!(),
+            }
+        }
+        res
+    }
 }
 impl Default for DiffPatch {
     fn default() -> Self {
diff --git a/patch-db/src/store.rs b/patch-db/src/store.rs
index cb6199e..9c0ae34 100644
--- a/patch-db/src/store.rs
+++ b/patch-db/src/store.rs
@@ -123,6 +123,12 @@ impl Store {
         self.file.unlock(true).map_err(|e| e.1)?;
         Ok(())
     }
+    pub fn exists<S: AsRef<str>, V: SegList>(
+        &self,
+        ptr: &JsonPointer<S, V>,
+    ) -> Result<bool, Error> {
+        Ok(ptr.get(self.get_data()?).unwrap_or(&Value::Null) != &Value::Null)
+    }
     pub fn get<T: for<'de> Deserialize<'de>, S: AsRef<str>, V: SegList>(
         &self,
         ptr: &JsonPointer<S, V>,
@@ -190,6 +196,12 @@ impl PatchDb {
             subscriber: Arc::new(subscriber),
         })
     }
+    pub async fn exists<S: AsRef<str>, V: SegList>(
+        &self,
+        ptr: &JsonPointer<S, V>,
+    ) -> Result<bool, Error> {
+        self.store.read().await.exists(ptr)
+    }
     pub async fn get<T: for<'de> Deserialize<'de>, S: AsRef<str>, V: SegList>(
         &self,
         ptr: &JsonPointer<S, V>,
diff --git a/patch-db/src/transaction.rs b/patch-db/src/transaction.rs
index fef9f0b..3c20aeb 100644
--- a/patch-db/src/transaction.rs
+++ b/patch-db/src/transaction.rs
@@ -15,6 +15,11 @@ use crate::Error;
 
 pub trait Checkpoint: Sized {
     fn rebase(&mut self) -> Result<(), Error>;
+    fn exists<'a, S: AsRef<str> + Send + Sync + 'a, V: SegList + Send + Sync + 'a>(
+        &'a mut self,
+        ptr: &'a JsonPointer<S, V>,
+        store_read_lock: Option<RwLockReadGuard<'a, Store>>,
+    ) -> BoxFuture<'a, Result<bool, Error>>;
     fn get_value<'a, S: AsRef<str> + Send + Sync + 'a, V: SegList + Send + Sync + 'a>(
         &'a mut self,
         ptr: &'a JsonPointer<S, V>,
@@ -73,6 +78,23 @@ impl Transaction {
         }
         Ok(())
     }
+    async fn exists<S: AsRef<str>, V: SegList>(
+        &mut self,
+        ptr: &JsonPointer<S, V>,
+        store_read_lock: Option<RwLockReadGuard<'_, Store>>,
+    ) -> Result<bool, Error> {
+        let exists = {
+            let store_lock = self.db.store.clone();
+            let store = if let Some(store_read_lock) = store_read_lock {
+                store_read_lock
+            } else {
+                store_lock.read().await
+            };
+            self.rebase()?;
+            ptr.get(store.get_data()?).unwrap_or(&Value::Null) != &Value::Null
+        };
+        Ok(self.updates.for_path(ptr).exists().unwrap_or(exists))
+    }
     async fn get_value<S: AsRef<str>, V: SegList>(
         &mut self,
         ptr: &JsonPointer<S, V>,
@@ -164,6 +186,13 @@ impl<'a> Checkpoint for &'a mut Transaction {
     fn rebase(&mut self) -> Result<(), Error> {
         Transaction::rebase(self)
     }
+    fn exists<'b, S: AsRef<str> + Send + Sync + 'b, V: SegList + Send + Sync + 'b>(
+        &'b mut self,
+        ptr: &'b JsonPointer<S, V>,
+        store_read_lock: Option<RwLockReadGuard<'b, Store>>,
+    ) -> BoxFuture<'b, Result<bool, Error>> {
+        Transaction::exists(self, ptr, store_read_lock).boxed()
+    }
     fn get_value<'b, S: AsRef<str> + Send + Sync + 'b, V: SegList + Send + Sync + 'b>(
         &'b mut self,
         ptr: &'b JsonPointer<S, V>,
@@ -241,6 +270,23 @@ impl<Tx: Checkpoint + Send + Sync> SubTransaction<Tx> {
         }
         Ok(())
     }
+    async fn exists<S: AsRef<str> + Send + Sync, V: SegList + Send + Sync>(
+        &mut self,
+        ptr: &JsonPointer<S, V>,
+        store_read_lock: Option<RwLockReadGuard<'_, Store>>,
+    ) -> Result<bool, Error> {
+        let exists = {
+            let store_lock = self.parent.store();
+            let store = if let Some(store_read_lock) = store_read_lock {
+                store_read_lock
+            } else {
+                store_lock.read().await
+            };
+            self.rebase()?;
+            self.parent.exists(ptr, Some(store)).await?
+        };
+        Ok(self.updates.for_path(ptr).exists().unwrap_or(exists))
+    }
     async fn get_value<S: AsRef<str> + Send + Sync, V: SegList + Send + Sync>(
         &mut self,
         ptr: &JsonPointer<S, V>,
@@ -336,6 +382,13 @@ impl<'a, Tx: Checkpoint + Send + Sync> Checkpoint for &'a mut SubTransaction<Tx>
     fn rebase(&mut self) -> Result<(), Error> {
         SubTransaction::rebase(self)
     }
+    fn exists<'b, S: AsRef<str> + Send + Sync + 'b, V: SegList + Send + Sync + 'b>(
+        &'b mut self,
+        ptr: &'b JsonPointer<S, V>,
+        store_read_lock: Option<RwLockReadGuard<'b, Store>>,
+    ) -> BoxFuture<'b, Result<bool, Error>> {
+        SubTransaction::exists(self, ptr, store_read_lock).boxed()
+    }
     fn get_value<'b, S: AsRef<str> + Send + Sync + 'b, V: SegList + Send + Sync + 'b>(
         &'b mut self,
         ptr: &'b JsonPointer<S, V>,