data inserting

Cargo.lock

@@ -12,6 +12,12 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "either"
+version = "1.6.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e78d4f1cc4ae33bbfc157ed5d5a5ef3bc29227303d595861deb238fcec4e9457"
+
 [[package]]
 name = "getrandom"
 version = "0.2.2"
@@ -23,6 +29,15 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "itertools"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "37d572918e350e82412fe766d24b15e6682fb2ed2bbe018280caa810397cb319"
+dependencies = [
+ "either",
+]
+
 [[package]]
 name = "itoa"
 version = "0.4.7"
@@ -213,6 +228,7 @@ name = "yopa"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "itertools",
  "log",
  "serde",
  "serde_json",

Cargo.toml

@@ -17,3 +17,4 @@ serde = { version = "1.0.120", features = ["derive"] }
 #parking_lot = "0.11.1"
 anyhow = "1.0.38"
 thiserror = "1.0.23"
+itertools = "0.10.0"

src/main.rs

@@ -5,6 +5,8 @@ use log::LevelFilter;
 mod yopa;
 use yopa::model;
 use yopa::model::DataType;
+use crate::yopa::insert::{InsertObj, InsertValue, InsertRel};
+use crate::yopa::data::TypedValue;
 
 mod cool;
 
@@ -21,15 +23,15 @@ fn _main() -> anyhow::Result<()> {
 
     let mut store = yopa::InMemoryStorage::new();
 
-    let recipe_tid = store.insert_object_template(model::ObjectTemplate {
+    let Recipe = store.define_object(model::ObjectModel {
         id: Default::default(),
         name: "recipe".to_string(),
         parent_tpl_id: None
     })?;
 
-    store.insert_property_template(model::PropertyTemplate {
+    let RecipeTitle = store.define_property(model::PropertyModel {
         id: Default::default(),
-        parent_tpl_id: recipe_tid,
+        parent_tpl_id: Recipe,
         name: "title".to_string(),
         optional: false,
         multiple: false,
@@ -37,9 +39,9 @@ fn _main() -> anyhow::Result<()> {
         default: None
     })?;
 
-    store.insert_property_template(model::PropertyTemplate {
+    let PrepHours = store.define_property(model::PropertyModel {
         id: Default::default(),
-        parent_tpl_id: recipe_tid,
+        parent_tpl_id: Recipe,
         name: "prep_hours".to_string(),
         optional: true,
         multiple: false,
@@ -47,24 +49,34 @@ fn _main() -> anyhow::Result<()> {
         default: None
     })?;
 
-    let book_tid = store.insert_object_template(model::ObjectTemplate {
+    let Book = store.define_object(model::ObjectModel {
         id: Default::default(),
         name: "book".to_string(),
         parent_tpl_id: None
     })?;
 
-    let br_rid = store.insert_relation_template(model::RelationTemplate {
+    let BookName = store.define_property(model::PropertyModel {
         id: Default::default(),
-        object_tpl_id: recipe_tid,
+        parent_tpl_id: Book,
-        name: "book reference".to_string(),
+        name: "name".to_string(),
         optional: false,
         multiple: false,
-        related_tpl_id: book_tid
+        data_type: DataType::String,
+        default: None
     })?;
 
-    store.insert_property_template(model::PropertyTemplate {
+    let BookToRecipe = store.define_relation(model::RelationModel {
         id: Default::default(),
-        parent_tpl_id: br_rid,
+        object_tpl_id: Recipe,
+        name: "book reference".to_string(),
+        optional: true,
+        multiple: true,
+        related_tpl_id: Book
+    })?;
+
+    let BookToRecipePage = store.define_property(model::PropertyModel {
+        id: Default::default(),
+        parent_tpl_id: BookToRecipe,
         name: "page".to_string(),
         optional: true,
         multiple: false,
@@ -74,5 +86,40 @@ fn _main() -> anyhow::Result<()> {
 
     debug!("{:#?}", store);
 
+    let MyBook1 = store.insert_object(InsertObj {
+        model_id: Book,
+        values: vec![
+            InsertValue {
+                model_id: BookName,
+                value: TypedValue::String("Recipe Book 1".into()),
+            }
+        ],
+        relations: vec![],
+    })?;
+
+    store.insert_object(InsertObj {
+        model_id: Recipe,
+        values: vec![
+            InsertValue {
+                model_id: RecipeTitle,
+                value: TypedValue::String("Pancakes".into()),
+            }
+        ],
+        relations: vec![
+            InsertRel {
+                model_id: BookToRecipe,
+                related_id: MyBook1,
+                values: vec![
+                    InsertValue {
+                        model_id: BookToRecipePage,
+                        value: TypedValue::Integer(123),
+                    }
+                ]
+            }
+        ],
+    });
+
+    debug!("{:#?}", store);
+
     Ok(())
 }

src/yopa.rs

@@ -1,21 +1,37 @@
 use std::collections::{HashMap};
-use crate::yopa::model::{ObjectTemplate, ID};
 use thiserror::Error;
 
 use crate::cool::{map_drain_filter, KVVecToKeysOrValues};
+use model::{ObjectModel};
+use insert::InsertObj;
+use itertools::Itertools;
+use std::borrow::Cow;
+use model::Describe;
+use insert::InsertValue;
+use data::TypedValue;
+
+/// Common identifier type
+#[allow(non_camel_case_types)]
+pub type ID = uuid::Uuid;
 
 /// Data model structs and enums
 pub mod model {
     use serde::{Serialize, Deserialize};
     use std::borrow::Cow;
+    use super::ID;
+    use super::data::TypedValue;
+    use std::fmt::{Display, Formatter};
+    use std::fmt;
 
-    /// Common identifier type
+    /// Get a description of a struct
-    #[allow(non_camel_case_types)]
+    pub trait Describe {
-    pub type ID = uuid::Uuid;
+        /// Short but informative description for error messages
+        fn describe(&self) -> String;
+    }
 
     /// Object template
     #[derive(Debug,Clone,Serialize,Deserialize)]
-    pub struct ObjectTemplate {
+    pub struct ObjectModel {
         /// PK
         pub id : ID,
         /// Template name, unique within the database
@@ -26,7 +42,7 @@ pub mod model {
 
     /// Relation between templates
     #[derive(Debug,Clone,Serialize,Deserialize)]
-    pub struct RelationTemplate {
+    pub struct RelationModel {
         /// PK
         pub id: ID,
         /// Object template ID
@@ -43,7 +59,7 @@ pub mod model {
 
     /// Property definition
     #[derive(Debug,Clone,Serialize,Deserialize)]
-    pub struct PropertyTemplate {
+    pub struct PropertyModel {
         /// PK
         pub id: ID,
         /// Object or Reference template ID
@@ -61,7 +77,7 @@ pub mod model {
     }
 
     /// Value data type
-    #[derive(Debug,Clone,Serialize,Deserialize)]
+    #[derive(Debug,Clone,Copy,Serialize,Deserialize,Eq,PartialEq)]
     pub enum DataType {
         /// Text
         String,
@@ -73,8 +89,36 @@ pub mod model {
         Boolean,
     }
 
+    impl Display for ObjectModel {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            write!(f, "object \"{}\" ({})", self.name, self.id)
+        }
+    }
+
+    impl Display for RelationModel {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            write!(f, "relation \"{}\" ({})", self.name, self.id)
+        }
+    }
+
+    impl Display for PropertyModel {
+        fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+            write!(f, "property \"{}\" ({})", self.name, self.id)
+        }
+    }
+}
+
+/// Data value structs
+pub mod data {
+    use serde::{Serialize, Deserialize};
+    use super::ID;
+    use std::borrow::Cow;
+    use super::StorageError;
+    use std::num::ParseIntError;
+    use crate::yopa::model::DataType;
+
     /// Value of a particular type
-    #[derive(Debug,Clone,Serialize,Deserialize)]
+    #[derive(Debug,Clone,Serialize,Deserialize,PartialEq)]
     pub enum TypedValue {
         /// Text
         String(Cow<'static, str>),
@@ -85,12 +129,142 @@ pub mod model {
         /// Boolean yes/no
         Boolean(bool),
     }
-}
 
-/// Data value structs
+    impl TypedValue {
-pub mod data {
+        /// Try ot cast to another type. On error, the original value is returned as Err.
-    use serde::{Serialize, Deserialize};
+        pub fn cast_to(self, ty : DataType) -> Result<TypedValue, TypedValue> {
-    use crate::yopa::model::{ID, TypedValue};
+            match (self, ty) {
+                // to string
+                (s @ TypedValue::String(_), DataType::String) => Ok(s),
+                (TypedValue::Integer(i), DataType::String) => Ok(TypedValue::String(i.to_string().into())),
+                (TypedValue::Decimal(f), DataType::String) => Ok(TypedValue::String(f.to_string().into())),
+                (TypedValue::Boolean(b), DataType::String) => Ok(TypedValue::String(Cow::Borrowed(if b { "1" } else { "0" }))),
+                // to int
+                (TypedValue::String(s), DataType::Integer) => {
+                    match s.parse::<i64>() {
+                        Ok(i) => Ok(TypedValue::Integer(i)),
+                        Err(_) => Err(TypedValue::String(s))
+                    }
+                },
+                (s @ TypedValue::Integer(_), DataType::Integer) => Ok(s),
+                (TypedValue::Decimal(f), DataType::Integer) => Ok(TypedValue::Integer(f.round() as i64)),
+                (TypedValue::Boolean(b), DataType::Integer) => Ok(TypedValue::Integer(if b { 1 } else { 0 })),
+                // to float
+                (TypedValue::String(s), DataType::Decimal) => {
+                    match s.parse::<f64>() {
+                        Ok(i) => Ok(TypedValue::Decimal(i)),
+                        Err(_) => Err(TypedValue::String(s))
+                    }
+                },
+                (TypedValue::Integer(i), DataType::Decimal) => Ok(TypedValue::Decimal(i as f64)),
+                (d @ TypedValue::Decimal(_), DataType::Decimal) => Ok(d),
+                (e @ TypedValue::Boolean(_), DataType::Decimal) => Err(e),
+                // to bool
+                (TypedValue::String(s), DataType::Boolean) => {
+                    match &(&s).to_ascii_lowercase()[..] {
+                        "y" | "yes" | "true" | "1" => {
+                            Ok(TypedValue::Boolean(true))
+                        }
+                        "n" | "no" | "false" | "0" => {
+                            Ok(TypedValue::Boolean(false))
+                        }
+                        _ => {
+                            Err(TypedValue::String(s))
+                        }
+                    }
+                },
+                (TypedValue::Integer(i), DataType::Boolean) => Ok(TypedValue::Boolean(i != 0)),
+                (e @ TypedValue::Decimal(_), DataType::Boolean) => Err(e),
+                (b @ TypedValue::Boolean(_), DataType::Boolean) => Ok(b),
+                (s, _) => {
+                    Err(s)
+                }
+            }
+        }
+    }
+
+    #[cfg(test)]
+    mod tests {
+        use super::TypedValue;
+        use crate::yopa::model::DataType;
+
+        #[test]
+        fn test_cast_to_bool() {
+            // Cast to bool
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::Boolean(true).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::Boolean(false).cast_to(DataType::Boolean));
+
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::Integer(123).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::Integer(0).cast_to(DataType::Boolean));
+
+            assert_eq!(Err(TypedValue::Decimal(0.0)), TypedValue::Decimal(0.0).cast_to(DataType::Boolean));
+            assert_eq!(Err(TypedValue::Decimal(123.0)), TypedValue::Decimal(123.0).cast_to(DataType::Boolean));
+
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::String("true".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::String("1".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::String("y".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(true)), TypedValue::String("yes".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::String("false".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::String("0".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::String("n".into()).cast_to(DataType::Boolean));
+            assert_eq!(Ok(TypedValue::Boolean(false)), TypedValue::String("no".into()).cast_to(DataType::Boolean));
+            assert_eq!(Err(TypedValue::String("blorg".into())), TypedValue::String("blorg".into()).cast_to(DataType::Boolean));
+        }
+
+        #[test]
+        fn test_cast_to_int() {
+            // Cast to bool
+            assert_eq!(Ok(TypedValue::Integer(1)), TypedValue::Boolean(true).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(0)), TypedValue::Boolean(false).cast_to(DataType::Integer));
+
+            assert_eq!(Ok(TypedValue::Integer(123)), TypedValue::Integer(123).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(0)), TypedValue::Integer(0).cast_to(DataType::Integer));
+
+            assert_eq!(Ok(TypedValue::Integer(0)), TypedValue::Decimal(0.0).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(123)), TypedValue::Decimal(123.0).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(-124)), TypedValue::Decimal(-123.7).cast_to(DataType::Integer));
+
+            assert_eq!(Ok(TypedValue::Integer(123)), TypedValue::String("123".into()).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(-123)), TypedValue::String("-123".into()).cast_to(DataType::Integer));
+            assert_eq!(Ok(TypedValue::Integer(0)), TypedValue::String("0".into()).cast_to(DataType::Integer));
+            assert_eq!(Err(TypedValue::String("123.456".into())), TypedValue::String("123.456".into()).cast_to(DataType::Integer));
+            assert_eq!(Err(TypedValue::String("-123.456".into())), TypedValue::String("-123.456".into()).cast_to(DataType::Integer));
+        }
+
+        #[test]
+        fn test_cast_to_decimal() {
+            // Cast to bool
+            assert_eq!(Err(TypedValue::Boolean(true)), TypedValue::Boolean(true).cast_to(DataType::Decimal));
+            assert_eq!(Err(TypedValue::Boolean(false)), TypedValue::Boolean(false).cast_to(DataType::Decimal));
+
+            assert_eq!(Ok(TypedValue::Decimal(123.0)), TypedValue::Integer(123).cast_to(DataType::Decimal));
+            assert_eq!(Ok(TypedValue::Decimal(0.0)), TypedValue::Integer(0).cast_to(DataType::Decimal));
+
+            assert_eq!(Ok(TypedValue::Decimal(0.0)), TypedValue::Decimal(0.0).cast_to(DataType::Decimal));
+            assert_eq!(Ok(TypedValue::Decimal(-123.7)), TypedValue::Decimal(-123.7).cast_to(DataType::Decimal));
+
+            assert_eq!(Ok(TypedValue::Decimal(123.0)), TypedValue::String("123".into()).cast_to(DataType::Decimal));
+            assert_eq!(Ok(TypedValue::Decimal(-123.0)), TypedValue::String("-123".into()).cast_to(DataType::Decimal));
+            assert_eq!(Ok(TypedValue::Decimal(0.0)), TypedValue::String("0".into()).cast_to(DataType::Decimal));
+            assert_eq!(Ok(TypedValue::Decimal(-123.456)), TypedValue::String("-123.456".into()).cast_to(DataType::Decimal));
+        }
+
+        #[test]
+        fn test_cast_to_string() {
+            // Cast to bool
+            assert_eq!(Ok(TypedValue::String("1".into())), TypedValue::Boolean(true).cast_to(DataType::String));
+            assert_eq!(Ok(TypedValue::String("0".into())), TypedValue::Boolean(false).cast_to(DataType::String));
+
+            assert_eq!(Ok(TypedValue::String("123".into())), TypedValue::Integer(123).cast_to(DataType::String));
+            assert_eq!(Ok(TypedValue::String("0".into())), TypedValue::Integer(0).cast_to(DataType::String));
+
+            assert_eq!(Ok(TypedValue::String("0".into())), TypedValue::Decimal(0.0).cast_to(DataType::String));
+            assert_eq!(Ok(TypedValue::String("123".into())), TypedValue::Decimal(123.0).cast_to(DataType::String));
+            assert_eq!(Ok(TypedValue::String("-123.5".into())), TypedValue::Decimal(-123.5).cast_to(DataType::String));
+
+            assert_eq!(Ok(TypedValue::String("blorg".into())), TypedValue::String("blorg".into()).cast_to(DataType::String));
+        }
+    }
 
     /// Instance of an object
     #[derive(Debug,Clone,Serialize,Deserialize)]
@@ -98,7 +272,7 @@ pub mod data {
         /// PK
         pub id : ID,
         /// Object template ID
-        pub object_tpl_id: ID,
+        pub model_id: ID,
     }
 
     /// Relation between two objects
@@ -109,7 +283,7 @@ pub mod data {
         /// Source object ID
         pub object_id : ID,
         /// Relation template ID
-        pub rel_tpl_id: ID,
+        pub model_id: ID,
         /// Related object ID
         pub related_id : ID,
     }
@@ -122,21 +296,51 @@ pub mod data {
         /// Owning object ID
         pub object_id : ID,
         /// Property template ID
-        pub prop_tpl_id: ID,
+        pub model_id: ID,
         /// Property value
         pub value : TypedValue,
     }
 }
 
+/// Helper struct for inserting relational data in the database
+pub mod insert {
+    use super::ID;
+    use super::data::TypedValue;
+    use serde::{Serialize,Deserialize};
+
+    /// Value to insert
+    #[derive(Debug,Clone,Serialize,Deserialize)]
+    pub struct InsertValue {
+        pub model_id: ID,
+        pub value: TypedValue
+    }
+
+    /// Info for inserting a relation
+    #[derive(Debug,Clone,Serialize,Deserialize)]
+    pub struct InsertRel {
+        pub model_id: ID,
+        pub related_id: ID,
+        pub values: Vec<InsertValue>
+    }
+
+    /// Info for inserting a relation
+    #[derive(Debug,Clone,Serialize,Deserialize)]
+    pub struct InsertObj {
+        pub model_id: ID,
+        pub values: Vec<InsertValue>,
+        pub relations: Vec<InsertRel>,
+    }
+}
+
 #[derive(Debug, Default)]
 pub struct InMemoryStorage {
-    tpl_objects: HashMap<ID, model::ObjectTemplate>,
+    obj_models: HashMap<ID, model::ObjectModel>,
-    tpl_relations: HashMap<ID, model::RelationTemplate>,
+    rel_models: HashMap<ID, model::RelationModel>,
-    tpl_properties: HashMap<ID, model::PropertyTemplate>,
+    prop_models: HashMap<ID, model::PropertyModel>,
 
-    data_objects: HashMap<ID, data::Object>,
+    objects: HashMap<ID, data::Object>,
-    data_relations: HashMap<ID, data::Relation>,
+    relations: HashMap<ID, data::Relation>,
-    data_values: HashMap<ID, data::Value>,
+    properties: HashMap<ID, data::Value>,
 }
 
 fn next_id() -> ID {
@@ -150,9 +354,9 @@ pub fn zero_id() -> ID {
 #[derive(Debug,Error)]
 pub enum StorageError {
     #[error("Referenced {0} does not exist")]
-    NotExist(&'static str),
+    NotExist(Cow<'static, str>),
     #[error("Schema constraint violation: {0}")]
-    ConstraintViolation(&'static str),
+    ConstraintViolation(Cow<'static, str>),
 }
 
 impl InMemoryStorage {
@@ -160,162 +364,224 @@ impl InMemoryStorage {
         Self::default()
     }
 
-    pub fn insert_object_template(&mut self, mut tpl : model::ObjectTemplate) -> Result<ID, StorageError> {
+    pub fn define_object(&mut self, mut tpl : model::ObjectModel) -> Result<ID, StorageError> {
         if let Some(pid) = tpl.parent_tpl_id {
-            if !self.tpl_objects.contains_key(&pid) {
+            if !self.obj_models.contains_key(&pid) {
-                return Err(StorageError::NotExist("parent object template"));
+                return Err(StorageError::NotExist(format!("parent object model {}", pid).into()));
             }
         }
 
-        if self.tpl_objects.iter().find(|(_, t)| t.name == tpl.name).is_some() {
+        if self.obj_models.iter().find(|(_, t)| t.name == tpl.name).is_some() {
-            return Err(StorageError::ConstraintViolation("object template with this name already exists"));
+            return Err(StorageError::ConstraintViolation(format!("object model with the name \"{}\" already exists", tpl.name).into()));
         }
 
         let id = next_id();
         tpl.id = id;
-        self.tpl_objects.insert(id, tpl);
+        self.obj_models.insert(id, tpl);
         Ok(id)
     }
 
-    pub fn insert_relation_template(&mut self, mut rel: model::RelationTemplate) -> Result<ID, StorageError> {
+    pub fn define_relation(&mut self, mut rel: model::RelationModel) -> Result<ID, StorageError> {
-        if !self.tpl_objects.contains_key(&rel.object_tpl_id) {
+        if !self.obj_models.contains_key(&rel.object_tpl_id) {
-            return Err(StorageError::NotExist("origin object template"));
+            return Err(StorageError::NotExist(format!("source object model {}", rel.object_tpl_id).into()));
         }
-        if !self.tpl_objects.contains_key(&rel.related_tpl_id) {
+        if !self.obj_models.contains_key(&rel.related_tpl_id) {
-            return Err(StorageError::NotExist("related object template"));
+            return Err(StorageError::NotExist(format!("related object model {}", rel.related_tpl_id).into()));
         }
 
-        if self.tpl_relations.iter().find(|(_, t)| t.name == rel.name && t.object_tpl_id == rel.object_tpl_id).is_some() {
+        if self.rel_models.iter().find(|(_, t)| t.name == rel.name && t.object_tpl_id == rel.object_tpl_id).is_some() {
-            return Err(StorageError::ConstraintViolation("relation with this name and parent already exists"));
+            return Err(StorageError::ConstraintViolation(
+                format!("relation with the name \"{}\" and on model {} already exists", rel.name, rel.object_tpl_id).into()));
         }
 
         let id = next_id();
         rel.id = id;
-        self.tpl_relations.insert(id, rel);
+        self.rel_models.insert(id, rel);
         Ok(id)
     }
 
-    pub fn insert_property_template(&mut self, mut prop: model::PropertyTemplate) -> Result<ID, StorageError> {
+    pub fn define_property(&mut self, mut prop: model::PropertyModel) -> Result<ID, StorageError> {
-        if !self.tpl_objects.contains_key(&prop.parent_tpl_id) {
+        if !self.obj_models.contains_key(&prop.parent_tpl_id) {
             // Maybe it's attached to a relation?
-            if !self.tpl_relations.contains_key(&prop.parent_tpl_id) {
+            if !self.rel_models.contains_key(&prop.parent_tpl_id) {
-                return Err(StorageError::NotExist("object or reference template"));
+                return Err(StorageError::NotExist(format!("object or relation model {}", prop.parent_tpl_id).into()));
             }
         }
 
-        if self.tpl_properties.iter().find(|(_, t)| t.parent_tpl_id == prop.parent_tpl_id && t.name == prop.name).is_some() {
+        if self.prop_models.iter().find(|(_, t)| t.parent_tpl_id == prop.parent_tpl_id && t.name == prop.name).is_some() {
-            return Err(StorageError::ConstraintViolation("property with this name and parent already exists"));
+            return Err(StorageError::ConstraintViolation(
+                format!("property with the name \"{}\" already exists on model {}", prop.name, prop.parent_tpl_id).into()));
+        }
+
+        // Ensure the default type is compatible
+        if let Some(d) = prop.default {
+            prop.default = Some(match d.cast_to(prop.data_type) {
+                Ok(v) => v,
+                Err(d) => return Err(StorageError::NotExist(format!("default value {:?} has invalid type", d).into()))
+            });
         }
 
         let id = next_id();
         prop.id = id;
-        self.tpl_properties.insert(id, prop);
+        self.prop_models.insert(id, prop);
         Ok(id)
     }
 
-    pub fn delete_object_template(&mut self, id : ID) -> Result<ObjectTemplate, StorageError> {
+    pub fn undefine_object(&mut self, id : ID) -> Result<ObjectModel, StorageError> {
-        return if let Some(t) = self.tpl_objects.remove(&id) {
+        return if let Some(t) = self.obj_models.remove(&id) {
             // Remove relation templates
-            let removed_relation_ids = map_drain_filter(&mut self.tpl_relations, |_k, v| v.object_tpl_id == id || v.related_tpl_id == id)
+            let removed_relation_ids = map_drain_filter(&mut self.rel_models, |_k, v| v.object_tpl_id == id || v.related_tpl_id == id)
                 .keys();
 
             // Remove related property templates
-            let removed_prop_ids = map_drain_filter(&mut self.tpl_properties, |_k, v| v.parent_tpl_id == id || removed_relation_ids.contains(&v.parent_tpl_id))
+            let removed_prop_ids = map_drain_filter(&mut self.prop_models, |_k, v| v.parent_tpl_id == id || removed_relation_ids.contains(&v.parent_tpl_id))
                 .keys();
 
             // Remove objects
-            let _ = map_drain_filter(&mut self.data_objects, |_k, v| v.object_tpl_id == id);
+            let _ = map_drain_filter(&mut self.objects, |_k, v| v.model_id == id);
 
             // Remove property values
-            let _ = map_drain_filter(&mut self.data_values, |_k, v| removed_prop_ids.contains(&v.prop_tpl_id));
+            let _ = map_drain_filter(&mut self.properties, |_k, v| removed_prop_ids.contains(&v.model_id));
 
             // Remove relations
-            let _ = map_drain_filter(&mut self.data_relations, |_k, v| removed_relation_ids.contains(&v.rel_tpl_id));
+            let _ = map_drain_filter(&mut self.relations, |_k, v| removed_relation_ids.contains(&v.model_id));
 
             // Related object remain untouched, so there can be a problem with orphans. This is up to the application to deal with.
 
             Ok(t)
         } else {
-            Err(StorageError::NotExist("object template"))
+            Err(StorageError::NotExist(format!("object model {}", id).into()))
         }
     }
 
-    pub fn delete_relation_template(&mut self, id : ID) -> Result<model::RelationTemplate, StorageError> {
+    pub fn undefine_relation(&mut self, id : ID) -> Result<model::RelationModel, StorageError> {
-        return if let Some(t) = self.tpl_relations.remove(&id) {
+        return if let Some(t) = self.rel_models.remove(&id) {
             // Remove relations
-            let _ = map_drain_filter(&mut self.data_relations, |_k, v| v.rel_tpl_id == id).keys();
+            let _ = map_drain_filter(&mut self.relations, |_k, v| v.model_id == id).keys();
 
             // Remove related property templates
-            let removed_prop_tpl_ids = map_drain_filter(&mut self.tpl_properties, |_k, v| v.parent_tpl_id == id).keys();
+            let removed_prop_tpl_ids = map_drain_filter(&mut self.prop_models, |_k, v| v.parent_tpl_id == id).keys();
 
-            let _ = map_drain_filter(&mut self.data_values, |_k, v| removed_prop_tpl_ids.contains(&v.prop_tpl_id));
+            let _ = map_drain_filter(&mut self.properties, |_k, v| removed_prop_tpl_ids.contains(&v.model_id));
 
             // Related object remain untouched, so there can be a problem with orphans. This is up to the application to deal with.
 
             Ok(t)
         } else {
-            Err(StorageError::NotExist("relation template"))
+            Err(StorageError::NotExist(format!("relation model {}", id).into()))
         }
     }
 
-    pub fn delete_property_template(&mut self, id : ID) -> Result<model::PropertyTemplate, StorageError> {
+    pub fn undefine_property(&mut self, id : ID) -> Result<model::PropertyModel, StorageError> {
-        return if let Some(t) = self.tpl_properties.remove(&id) {
+        return if let Some(t) = self.prop_models.remove(&id) {
             // Remove relations
-            let _ = map_drain_filter(&mut self.data_values, |_k, v| v.prop_tpl_id == id);
+            let _ = map_drain_filter(&mut self.properties, |_k, v| v.model_id == id);
             Ok(t)
         } else {
-            Err(StorageError::NotExist("property template"))
+            Err(StorageError::NotExist(format!("property model {}", id).into()))
         }
     }
 
     // DATA
 
-    pub fn insert_object(&mut self, mut obj : data::Object) -> Result<ID, StorageError> {
+    /// Insert object with relations, validating the data model
-        if !self.tpl_objects.contains_key(&obj.object_tpl_id) {
+    pub fn insert_object(&mut self, insobj: InsertObj) -> Result<ID, StorageError> {
-            return Err(StorageError::NotExist("object template"));
+        let obj_model_id = insobj.model_id;
+
+        let obj_model = match self.obj_models.get(&obj_model_id) {
+            Some(m) => m,
+            None => return Err(StorageError::NotExist(format!("object model {}", obj_model_id).into()))
+        };
+
+        let object_id = next_id();
+        let object = data::Object {
+            id: object_id,
+            model_id: obj_model_id
+        };
+
+        let find_values_to_insert = |values : Vec<InsertValue>, parent_id : ID| -> Result<Vec<data::Value>, StorageError> {
+            let mut values_by_id = values.into_iter().into_group_map_by(|iv| iv.model_id);
+            let mut values_to_insert = vec![];
+
+            for (id, prop) in self.prop_models.iter().filter(|(id, p)| p.parent_tpl_id == parent_id) {
+                if let Some(values) = values_by_id.remove(id) {
+                    if values.len() > 1 && !prop.multiple {
+                        return Err(StorageError::ConstraintViolation(format!("{} of {} cannot have multiple values", prop, obj_model).into()));
+                    }
+                    for val_instance in values {
+                        values_to_insert.push(data::Value {
+                            id: next_id(),
+                            object_id,
+                            model_id: prop.id,
+                            value: val_instance.value.cast_to(prop.data_type)
+                                .map_err(|v| StorageError::ConstraintViolation(format!("{} cannot accept value {:?}", prop, v).into()))?
+                        });
+                    }
+                } else {
+                    if !prop.optional {
+                        if let Some(def) = &prop.default {
+                            values_to_insert.push(data::Value {
+                                id: next_id(),
+                                object_id,
+                                model_id: prop.id,
+                                value: def.clone()
+                            });
+                        } else {
+                            return Err(StorageError::ConstraintViolation(format!("{} is required for {} (and no default value is defined)", prop, obj_model).into()));
                         }
-
-        let id = next_id();
-        obj.id = id;
-        self.data_objects.insert(id, obj);
-        Ok(id)
                     }
-
-    pub fn insert_value(&mut self, mut obj : data::Value) -> Result<ID, StorageError> {
-        if !self.tpl_properties.contains_key(&obj.prop_tpl_id) {
-            return Err(StorageError::NotExist("property template"));
                 }
-
-        if !self.data_objects.contains_key(&obj.object_id) {
-            return Err(StorageError::NotExist("parent object"));
             }
 
-        // TODO validate if it already exists
+            Ok(values_to_insert)
+        };
 
-        let id = next_id();
+        let mut values_to_insert = find_values_to_insert(insobj.values, obj_model_id)?;
-        obj.id = id;
+
-        self.data_values.insert(id, obj);
+        // And now ..... relations!
-        Ok(id)
+        let mut relations_by_id = insobj.relations.into_iter().into_group_map_by(|ir| ir.model_id);
+        let mut relations_to_insert = vec![];
+
+        for (relation_model_id, relation_model) in self.rel_models.iter().filter(|(id, r)| r.object_tpl_id == obj_model_id) {
+            if let Some(instances) = relations_by_id.remove(relation_model_id) {
+                if instances.len() > 1 && !relation_model.multiple {
+                    return Err(StorageError::ConstraintViolation(format!("{} of {} cannot be set multiply", relation_model, obj_model).into()));
                 }
 
-    pub fn insert_relation(&mut self, mut rel: data::Relation) -> Result<ID, StorageError> {
+                for rel_instance in instances {
-        if !self.tpl_relations.contains_key(&rel.rel_tpl_id) {
+                    if let Some(related) = self.objects.get(&rel_instance.related_id) {
-            return Err(StorageError::NotExist("relation template"));
+                        if related.model_id != relation_model.related_tpl_id {
+                            return Err(StorageError::ConstraintViolation(format!("{} of {} requires object of type {}, got {}", relation_model, obj_model, relation_model.related_tpl_id, related.model_id).into()));
                         }
+                    }
+
+                    // Relations can have properties
+                    values_to_insert.extend(find_values_to_insert(rel_instance.values, *relation_model_id)?);
 
-        if !self.data_objects.contains_key(&rel.object_id) {
+                    relations_to_insert.push(data::Relation {
-            return Err(StorageError::NotExist("parent object"));
+                        id: next_id(),
+                        object_id,
+                        model_id: rel_instance.model_id,
+                        related_id: rel_instance.related_id
+                    });
+                }
+            } else {
+                if !relation_model.optional {
+                    return Err(StorageError::ConstraintViolation(format!("{} is required for {}", relation_model, obj_model).into()));
+                }
+            }
         }
 
-        if !self.data_objects.contains_key(&rel.related_id) {
+        self.objects.insert(object_id, object);
-            return Err(StorageError::NotExist("related object"));
+
+        for rel in relations_to_insert {
+            self.relations.insert(rel.id, rel);
         }
 
-        // TODO validate if it already exists
+        for value in values_to_insert {
+            self.properties.insert(value.id, value);
+        }
 
-        let id = next_id();
+        Ok(object_id)
-        rel.id = id;
-        self.data_relations.insert(id, rel);
-        Ok(id)
     }
 }