Merge remote-tracking branch 'origin/master' into returning

.github/workflows/rust.yml

@@ -316,7 +316,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest]
-        path: [86, 249, 262]
+        path: [86, 249, 262, 319]
     steps:
       - uses: actions/checkout@v2
 

Cargo.toml

@@ -63,7 +63,7 @@ default = [
 ]
 macros = ["sea-orm-macros"]
 mock = []
-with-json = ["serde_json", "sea-query/with-json"]
+with-json = ["serde_json", "sea-query/with-json", "chrono/serde"]
 with-chrono = ["chrono", "sea-query/with-chrono"]
 with-rust_decimal = ["rust_decimal", "sea-query/with-rust_decimal"]
 with-uuid = ["uuid", "sea-query/with-uuid"]

examples/basic/src/operation.rs

@@ -1,5 +1,5 @@
 use super::*;
-use sea_orm::{entity::*, error::*, query::*, DbConn};
+use sea_orm::{entity::*, error::*, DbConn};
 
 pub async fn all_about_operation(db: &DbConn) -> Result<(), DbErr> {
     insert_and_update(db).await?;

issues/319/Cargo.toml

@@ -0,0 +1,18 @@
+[workspace]
+# A separate workspace
+
+[package]
+name = "sea-orm-issues-319"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+[dependencies]
+async-std = { version = "^1", features = ["attributes"] }
+serde = { version = "^1", features = ["derive"] }
+sea-orm = { path = "../../", features = [
+    "sqlx-mysql",
+    "runtime-async-std-native-tls",
+    "with-json",
+    "macros",
+], default-features = false }

issues/319/src/main.rs

@@ -0,0 +1,14 @@
+mod material;
+use sea_orm::*;
+
+#[async_std::main]
+pub async fn main() {
+    let db = Database::connect("mysql://sea:sea@localhost/bakery")
+        .await
+        .unwrap();
+
+    async_std::task::spawn(async move {
+        material::Entity::find().one(&db).await.unwrap();
+    })
+    .await;
+}

issues/319/src/material.rs

@@ -0,0 +1,20 @@
+use sea_orm::entity::prelude::*;
+use serde::{Serialize, Deserialize};
+
+#[derive(Clone, Debug, PartialEq, DeriveEntityModel, Serialize, Deserialize)]
+#[sea_orm(table_name = "materials")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    pub id: i32,
+    pub created_at: DateTimeWithTimeZone,
+    pub updated_at: DateTimeWithTimeZone,
+    pub name: String,
+    #[sea_orm(column_type = "Text", nullable)]
+    pub description: Option<String>,
+    pub tag_ids: Vec<u8>,
+}
+
+#[derive(Copy, Clone, Debug, EnumIter, DeriveRelation)]
+pub enum Relation {}
+
+impl ActiveModelBehavior for ActiveModel {}

src/database/connection.rs

@@ -4,7 +4,7 @@ use crate::{
 use futures::Stream;
 use std::{future::Future, pin::Pin};
 
-/// Creates constraints for any structure that wants to create a database connection
+/// Creates constraints for any structure that can create a database connection
 /// and execute SQL statements
 #[async_trait::async_trait]
 pub trait ConnectionTrait<'a>: Sync {

src/database/statement.rs

@@ -8,9 +8,10 @@ use std::fmt;
 pub struct Statement {
     /// The SQL query
     pub sql: String,
-    /// The values for the SQL statement
+    /// The values for the SQL statement's parameters
     pub values: Option<Values>,
-    /// The database backend to use
+    /// The database backend this statement is constructed for.
+    /// The SQL dialect and values should be valid for the DbBackend.
     pub db_backend: DbBackend,
 }
 
@@ -31,7 +32,7 @@ impl Statement {
     }
 
     /// Create a SQL statement from a [crate::DatabaseBackend], a
-    /// raw SQL statement and defined values
+    /// raw SQL statement and param values
     pub fn from_sql_and_values<I>(db_backend: DbBackend, sql: &str, values: I) -> Self
     where
         I: IntoIterator<Item = Value>,

src/database/stream/query.rs

@@ -1,3 +1,5 @@
+#![allow(missing_docs)]
+
 use std::{pin::Pin, task::Poll};
 
 #[cfg(feature = "mock")]

src/database/stream/transaction.rs

@@ -1,3 +1,5 @@
+#![allow(missing_docs)]
+
 use std::{ops::DerefMut, pin::Pin, task::Poll};
 
 use futures::Stream;
@@ -11,9 +13,9 @@ use futures::lock::MutexGuard;
 
 use crate::{DbErr, InnerConnection, QueryResult, Statement};
 
-#[ouroboros::self_referencing]
 /// `TransactionStream` cannot be used in a `transaction` closure as it does not impl `Send`.
 /// It seems to be a Rust limitation right now, and solution to work around this deemed to be extremely hard.
+#[ouroboros::self_referencing]
 pub struct TransactionStream<'a> {
     stmt: Statement,
     conn: MutexGuard<'a, InnerConnection>,

src/driver/mock.rs

@@ -23,7 +23,7 @@ pub struct MockDatabaseConnection {
     mocker: Mutex<Box<dyn MockDatabaseTrait>>,
 }
 
-/// A set of constraints for any type wanting to perform operations on the [MockDatabase]
+/// A Trait for any type wanting to perform operations on the [MockDatabase]
 pub trait MockDatabaseTrait: Send + Debug {
     /// Execute a statement in the [MockDatabase]
     fn execute(&mut self, counter: usize, stmt: Statement) -> Result<ExecResult, DbErr>;

src/driver/sqlx_common.rs

@@ -9,3 +9,8 @@ pub fn sqlx_error_to_exec_err(err: sqlx::Error) -> DbErr {
 pub fn sqlx_error_to_query_err(err: sqlx::Error) -> DbErr {
     DbErr::Query(err.to_string())
 }
+
+/// Converts an [sqlx::error] connection error to a [DbErr]
+pub fn sqlx_error_to_conn_err(err: sqlx::Error) -> DbErr {
+    DbErr::Conn(err.to_string())
+}

src/driver/sqlx_mysql.rs

@@ -41,12 +41,11 @@ impl SqlxMySqlConnector {
             use sqlx::ConnectOptions;
             opt.disable_statement_logging();
         }
-        if let Ok(pool) = options.pool_options().connect_with(opt).await {
-            Ok(DatabaseConnection::SqlxMySqlPoolConnection(
+        match options.pool_options().connect_with(opt).await {
+            Ok(pool) => Ok(DatabaseConnection::SqlxMySqlPoolConnection(
                 SqlxMySqlPoolConnection { pool },
-            ))
-        } else {
-            Err(DbErr::Conn("Failed to connect.".to_owned()))
+            )),
+            Err(e) => Err(sqlx_error_to_conn_err(e)),
         }
     }
 }

src/driver/sqlx_postgres.rs

@@ -41,12 +41,11 @@ impl SqlxPostgresConnector {
             use sqlx::ConnectOptions;
             opt.disable_statement_logging();
         }
-        if let Ok(pool) = options.pool_options().connect_with(opt).await {
-            Ok(DatabaseConnection::SqlxPostgresPoolConnection(
+        match options.pool_options().connect_with(opt).await {
+            Ok(pool) => Ok(DatabaseConnection::SqlxPostgresPoolConnection(
                 SqlxPostgresPoolConnection { pool },
-            ))
-        } else {
-            Err(DbErr::Conn("Failed to connect.".to_owned()))
+            )),
+            Err(e) => Err(sqlx_error_to_conn_err(e)),
         }
     }
 }

src/driver/sqlx_sqlite.rs

@@ -45,12 +45,11 @@ impl SqlxSqliteConnector {
         if options.get_max_connections().is_none() {
             options.max_connections(1);
         }
-        if let Ok(pool) = options.pool_options().connect_with(opt).await {
-            Ok(DatabaseConnection::SqlxSqlitePoolConnection(
+        match options.pool_options().connect_with(opt).await {
+            Ok(pool) => Ok(DatabaseConnection::SqlxSqlitePoolConnection(
                 SqlxSqlitePoolConnection { pool },
-            ))
-        } else {
-            Err(DbErr::Conn("Failed to connect.".to_owned()))
+            )),
+            Err(e) => Err(sqlx_error_to_conn_err(e)),
         }
     }
 }

src/entity/active_model.rs

@@ -76,12 +76,12 @@ where
     ActiveValue::unchanged(value)
 }
 
-/// Enforces a set of constraints on any type performing an Create, Update or Delete operation.
+/// A Trait for ActiveModel to perform Create, Update or Delete operation.
 /// The type must also implement the [EntityTrait].
 /// See module level docs [crate::entity] for a full example
 #[async_trait]
 pub trait ActiveModelTrait: Clone + Debug {
-    /// Enforce the type to the constraints of the [EntityTrait]
+    /// The Entity this ActiveModel belongs to
     type Entity: EntityTrait;
 
     /// Get a mutable [ActiveValue] from an ActiveModel
@@ -204,9 +204,7 @@ pub trait ActiveModelTrait: Clone + Debug {
     }
 }
 
-/// Enforce a set of constraints to a override the ActiveModel behavior
-/// Behaviors for users to override.
-/// The type must also implement the [ActiveModelTrait]
+/// A Trait for overriding the ActiveModel behavior
 ///
 /// ### Example
 /// ```ignore
@@ -261,7 +259,7 @@ pub trait ActiveModelBehavior: ActiveModelTrait {
     }
 }
 
-/// Enforce constraints for conversion to  an ActiveModel
+/// A Trait for any type that can be converted into an ActiveModel
 pub trait IntoActiveModel<A>
 where
     A: ActiveModelTrait,

src/entity/base_entity.rs

@@ -13,7 +13,7 @@ pub trait IdenStatic: Iden + Copy + Debug + 'static {
     fn as_str(&self) -> &str;
 }
 
-/// Enforces the naming of an entity to a set of constraints
+/// A Trait for mapping an Entity to a database table
 pub trait EntityName: IdenStatic + Default {
     /// Method to get the name for the schema, defaults to [Option::None] if not set
     fn schema_name(&self) -> Option<&str> {

src/entity/link.rs

@@ -6,7 +6,7 @@ use sea_query::{Alias, IntoIden, JoinType, SeaRc};
 /// Same as [RelationDef]
 pub type LinkDef = RelationDef;
 
-/// A set of constraints for links between Entities
+/// A Trait for links between Entities
 pub trait Linked {
     #[allow(missing_docs)]
     type FromEntity: EntityTrait;

src/entity/model.rs

@@ -5,7 +5,7 @@ use crate::{
 pub use sea_query::Value;
 use std::fmt::Debug;
 
-/// A set of constraints for a Model
+/// A Trait for a Model
 pub trait ModelTrait: Clone + Send + Debug {
     #[allow(missing_docs)]
     type Entity: EntityTrait;
@@ -35,7 +35,7 @@ pub trait ModelTrait: Clone + Send + Debug {
     }
 }
 
-/// A set of constraints for implementing a [QueryResult]
+/// A Trait for implementing a [QueryResult]
 pub trait FromQueryResult: Sized {
     /// Instantiate a Model from a [QueryResult]
     fn from_query_result(res: &QueryResult, pre: &str) -> Result<Self, DbErr>;

src/entity/prelude.rs

@@ -1,8 +1,8 @@
 pub use crate::{
     error::*, ActiveEnum, ActiveModelBehavior, ActiveModelTrait, ColumnDef, ColumnTrait,
     ColumnType, DatabaseConnection, DbConn, EntityName, EntityTrait, EnumIter, ForeignKeyAction,
-    Iden, IdenStatic, Linked, ModelTrait, PrimaryKeyToColumn, PrimaryKeyTrait, QueryFilter,
-    QueryResult, Related, RelationDef, RelationTrait, Select, Value,
+    Iden, IdenStatic, Linked, ModelTrait, PaginatorTrait, PrimaryKeyToColumn, PrimaryKeyTrait,
+    QueryFilter, QueryResult, Related, RelationDef, RelationTrait, Select, Value,
 };
 
 #[cfg(feature = "macros")]

src/entity/primary_key.rs

@@ -4,7 +4,7 @@ use sea_query::{FromValueTuple, IntoValueTuple};
 use std::fmt::Debug;
 
 //LINT: composite primary key cannot auto increment
-/// A set of constraints to be used to define a Primary Key.
+/// A Trait for to be used to define a Primary Key.
 ///
 /// A primary key can be derived manually
 ///

src/executor/paginator.rs

@@ -1,4 +1,7 @@
-use crate::{error::*, ConnectionTrait, DbBackend, SelectorTrait};
+use crate::{
+    error::*, ConnectionTrait, DbBackend, EntityTrait, FromQueryResult, Select, SelectModel,
+    SelectTwo, SelectTwoModel, Selector, SelectorTrait,
+};
 use async_stream::stream;
 use futures::Stream;
 use sea_query::{Alias, Expr, SelectStatement};
@@ -155,9 +158,77 @@ where
     }
 }
 
+#[async_trait::async_trait]
+/// A Trait for any type that can paginate results
+pub trait PaginatorTrait<'db, C>
+where
+    C: ConnectionTrait<'db>,
+{
+    /// Select operation
+    type Selector: SelectorTrait + Send + Sync + 'db;
+
+    /// Paginate the result of a select operation.
+    fn paginate(self, db: &'db C, page_size: usize) -> Paginator<'db, C, Self::Selector>;
+
+    /// Perform a count on the paginated results
+    async fn count(self, db: &'db C) -> Result<usize, DbErr>
+    where
+        Self: Send + Sized,
+    {
+        self.paginate(db, 1).num_items().await
+    }
+}
+
+impl<'db, C, S> PaginatorTrait<'db, C> for Selector<S>
+where
+    C: ConnectionTrait<'db>,
+    S: SelectorTrait + Send + Sync + 'db,
+{
+    type Selector = S;
+
+    fn paginate(self, db: &'db C, page_size: usize) -> Paginator<'db, C, S> {
+        Paginator {
+            query: self.query,
+            page: 0,
+            page_size,
+            db,
+            selector: PhantomData,
+        }
+    }
+}
+
+impl<'db, C, M, E> PaginatorTrait<'db, C> for Select<E>
+where
+    C: ConnectionTrait<'db>,
+    E: EntityTrait<Model = M>,
+    M: FromQueryResult + Sized + Send + Sync + 'db,
+{
+    type Selector = SelectModel<M>;
+
+    fn paginate(self, db: &'db C, page_size: usize) -> Paginator<'db, C, Self::Selector> {
+        self.into_model().paginate(db, page_size)
+    }
+}
+
+impl<'db, C, M, N, E, F> PaginatorTrait<'db, C> for SelectTwo<E, F>
+where
+    C: ConnectionTrait<'db>,
+    E: EntityTrait<Model = M>,
+    F: EntityTrait<Model = N>,
+    M: FromQueryResult + Sized + Send + Sync + 'db,
+    N: FromQueryResult + Sized + Send + Sync + 'db,
+{
+    type Selector = SelectTwoModel<M, N>;
+
+    fn paginate(self, db: &'db C, page_size: usize) -> Paginator<'db, C, Self::Selector> {
+        self.into_model().paginate(db, page_size)
+    }
+}
+
 #[cfg(test)]
 #[cfg(feature = "mock")]
 mod tests {
+    use super::*;
     use crate::entity::prelude::*;
     use crate::{tests_cfg::*, ConnectionTrait};
     use crate::{DatabaseConnection, DbBackend, MockDatabase, Transaction};

src/executor/select.rs

@@ -1,7 +1,7 @@
 use crate::{
     error::*, ConnectionTrait, EntityTrait, FromQueryResult, IdenStatic, Iterable, ModelTrait,
-    Paginator, PrimaryKeyToColumn, QueryResult, Select, SelectA, SelectB, SelectTwo, SelectTwoMany,
-    Statement, TryGetableMany,
+    PrimaryKeyToColumn, QueryResult, Select, SelectA, SelectB, SelectTwo, SelectTwoMany, Statement,
+    TryGetableMany,
 };
 use futures::{Stream, TryStreamExt};
 use sea_query::SelectStatement;
@@ -11,13 +11,13 @@ use std::pin::Pin;
 #[cfg(feature = "with-json")]
 use crate::JsonValue;
 
-/// Defines a type to do `SELECT` operations though a [SelectStatement] on a Model
+/// Defines a type to do `SELECT` operations through a [SelectStatement] on a Model
 #[derive(Clone, Debug)]
 pub struct Selector<S>
 where
     S: SelectorTrait,
 {
-    query: SelectStatement,
+    pub(crate) query: SelectStatement,
     selector: S,
 }
 
@@ -31,7 +31,7 @@ where
     selector: S,
 }
 
-/// Used to enforce constraints on any type that wants to perform SELECT queries
+/// A Trait for any type that can perform SELECT queries
 pub trait SelectorTrait {
     #[allow(missing_docs)]
     type Item: Sized;
@@ -250,7 +250,7 @@ where
         Selector::<SelectGetableValue<T, C>>::with_columns(self.query)
     }
 
-    /// Get one Model from a SELECT operation
+    /// Get one Model from the SELECT query
     pub async fn one<'a, C>(self, db: &C) -> Result<Option<E::Model>, DbErr>
     where
         C: ConnectionTrait<'a>,
@@ -258,7 +258,7 @@ where
         self.into_model().one(db).await
     }
 
-    /// Get all the Models from a SELECT operation
+    /// Get all Models from the SELECT query
     pub async fn all<'a, C>(self, db: &C) -> Result<Vec<E::Model>, DbErr>
     where
         C: ConnectionTrait<'a>,
@@ -276,26 +276,6 @@ where
     {
         self.into_model().stream(db).await
     }
-
-    /// Paginate the results of a SELECT operation on a Model
-    pub fn paginate<'a, C>(
-        self,
-        db: &'a C,
-        page_size: usize,
-    ) -> Paginator<'a, C, SelectModel<E::Model>>
-    where
-        C: ConnectionTrait<'a>,
-    {
-        self.into_model().paginate(db, page_size)
-    }
-
-    /// Perform a `COUNT` operation on a items on a Model using pagination
-    pub async fn count<'a, C>(self, db: &'a C) -> Result<usize, DbErr>
-    where
-        C: ConnectionTrait<'a>,
-    {
-        self.paginate(db, 1).num_items().await
-    }
 }
 
 impl<E, F> SelectTwo<E, F>
@@ -324,7 +304,7 @@ where
         }
     }
 
-    /// Get one Model from a Select operation
+    /// Get one Model from the Select query
     pub async fn one<'a, C>(self, db: &C) -> Result<Option<(E::Model, Option<F::Model>)>, DbErr>
     where
         C: ConnectionTrait<'a>,
@@ -332,7 +312,7 @@ where
         self.into_model().one(db).await
     }
 
-    /// Get all Models from a Select operation
+    /// Get all Models from the Select query
     pub async fn all<'a, C>(self, db: &C) -> Result<Vec<(E::Model, Option<F::Model>)>, DbErr>
     where
         C: ConnectionTrait<'a>,
@@ -350,26 +330,6 @@ where
     {
         self.into_model().stream(db).await
     }
-
-    /// Paginate the results of a select operation on two models
-    pub fn paginate<'a, C>(
-        self,
-        db: &'a C,
-        page_size: usize,
-    ) -> Paginator<'a, C, SelectTwoModel<E::Model, F::Model>>
-    where
-        C: ConnectionTrait<'a>,
-    {
-        self.into_model().paginate(db, page_size)
-    }
-
-    /// Perform a count on the paginated results
-    pub async fn count<'a, C>(self, db: &'a C) -> Result<usize, DbErr>
-    where
-        C: ConnectionTrait<'a>,
-    {
-        self.paginate(db, 1).num_items().await
-    }
 }
 
 impl<E, F> SelectTwoMany<E, F>
@@ -417,7 +377,7 @@ where
         self.into_model().stream(db).await
     }
 
-    /// Get all the Models from the select operation
+    /// Get all Models from the select operation
     pub async fn all<'a, C>(self, db: &C) -> Result<Vec<(E::Model, Vec<F::Model>)>, DbErr>
     where
         C: ConnectionTrait<'a>,
@@ -456,35 +416,36 @@ where
         }
     }
 
-    /// Get a Model from a Select operation
+    fn into_selector_raw<'a, C>(self, db: &C) -> SelectorRaw<S>
+    where
+        C: ConnectionTrait<'a>,
+    {
+        let builder = db.get_database_backend();
+        let stmt = builder.build(&self.query);
+        SelectorRaw {
+            stmt,
+            selector: self.selector,
+        }
+    }
+
+    /// Get an item from the Select query
     pub async fn one<'a, C>(mut self, db: &C) -> Result<Option<S::Item>, DbErr>
     where
         C: ConnectionTrait<'a>,
     {
-        let builder = db.get_database_backend();
         self.query.limit(1);
-        let row = db.query_one(builder.build(&self.query)).await?;
-        match row {
-            Some(row) => Ok(Some(S::from_raw_query_result(row)?)),
-            None => Ok(None),
-        }
+        self.into_selector_raw(db).one(db).await
     }
 
-    /// Get all results from a Select operation
+    /// Get all items from the Select query
     pub async fn all<'a, C>(self, db: &C) -> Result<Vec<S::Item>, DbErr>
     where
         C: ConnectionTrait<'a>,
     {
-        let builder = db.get_database_backend();
-        let rows = db.query_all(builder.build(&self.query)).await?;
-        let mut models = Vec::new();
-        for row in rows.into_iter() {
-            models.push(S::from_raw_query_result(row)?);
-        }
-        Ok(models)
+        self.into_selector_raw(db).all(db).await
     }
 
-    /// Stream the results of the operation
+    /// Stream the results of the Select operation
     pub async fn stream<'a: 'b, 'b, C>(
         self,
         db: &'a C,
@@ -493,25 +454,7 @@ where
         C: ConnectionTrait<'a>,
         S: 'b,
     {
-        let builder = db.get_database_backend();
-        let stream = db.stream(builder.build(&self.query)).await?;
-        Ok(Box::pin(stream.and_then(|row| {
-            futures::future::ready(S::from_raw_query_result(row))
-        })))
-    }
-
-    /// Paginate the result of a select operation on a Model
-    pub fn paginate<'a, C>(self, db: &'a C, page_size: usize) -> Paginator<'a, C, S>
-    where
-        C: ConnectionTrait<'a>,
-    {
-        Paginator {
-            query: self.query,
-            page: 0,
-            page_size,
-            db,
-            selector: PhantomData,
-        }
+        self.into_selector_raw(db).stream(db).await
     }
 }
 
@@ -519,8 +462,7 @@ impl<S> SelectorRaw<S>
 where
     S: SelectorTrait,
 {
-    /// Create `SelectorRaw` from Statment. Executing this `SelectorRaw` will
-    /// return a type `M` which implement `FromQueryResult`.
+    /// Select a custom Model from a raw SQL [Statement].
     pub fn from_statement<M>(stmt: Statement) -> SelectorRaw<SelectModel<M>>
     where
         M: FromQueryResult,
@@ -683,6 +625,7 @@ where
         }
     }
 
+    /// Get an item from the Select query
     /// ```
     /// # #[cfg(feature = "mock")]
     /// # use sea_orm::{error::*, tests_cfg::*, MockDatabase, Transaction, DbBackend};
@@ -725,6 +668,7 @@ where
         }
     }
 
+    /// Get all items from the Select query
     /// ```
     /// # #[cfg(feature = "mock")]
     /// # use sea_orm::{error::*, tests_cfg::*, MockDatabase, Transaction, DbBackend};
@@ -767,6 +711,21 @@ where
         }
         Ok(models)
     }
+
+    /// Stream the results of the Select operation
+    pub async fn stream<'a: 'b, 'b, C>(
+        self,
+        db: &'a C,
+    ) -> Result<Pin<Box<dyn Stream<Item = Result<S::Item, DbErr>> + 'b>>, DbErr>
+    where
+        C: ConnectionTrait<'a>,
+        S: 'b,
+    {
+        let stream = db.stream(self.stmt).await?;
+        Ok(Box::pin(stream.and_then(|row| {
+            futures::future::ready(S::from_raw_query_result(row))
+        })))
+    }
 }
 
 fn consolidate_query_result<L, R>(

src/query/mod.rs

@@ -22,4 +22,6 @@ pub use traits::*;
 pub use update::*;
 pub use util::*;
 
-pub use crate::{ConnectionTrait, InsertResult, Statement, UpdateResult, Value, Values};
+pub use crate::{
+    ConnectionTrait, InsertResult, PaginatorTrait, Statement, UpdateResult, Value, Values,
+};

src/query/traits.rs

@@ -1,7 +1,7 @@
 use crate::{DbBackend, Statement};
 use sea_query::QueryStatementBuilder;
 
-/// Enforces a set of constraints to any type performing queries on a Model or ActiveModel
+/// A Trait for any type performing queries on a Model or ActiveModel
 pub trait QueryTrait {
     /// Constrain the QueryStatement to [QueryStatementBuilder] trait
     type QueryStatement: QueryStatementBuilder;

src/schema/entity.rs

@@ -9,27 +9,27 @@ use sea_query::{
 
 impl Schema {
     /// Creates Postgres enums from an Entity. See [TypeCreateStatement] for more details
-    pub fn create_enum_from_entity<E>(entity: E, db_backend: DbBackend) -> Vec<TypeCreateStatement>
+    pub fn create_enum_from_entity<E>(&self, entity: E) -> Vec<TypeCreateStatement>
     where
         E: EntityTrait,
     {
-        create_enum_from_entity(entity, db_backend)
+        create_enum_from_entity(entity, self.backend)
     }
 
     /// Creates a table from an Entity. See [TableCreateStatement] for more details
-    pub fn create_table_from_entity<E>(entity: E, db_backend: DbBackend) -> TableCreateStatement
+    pub fn create_table_from_entity<E>(&self, entity: E) -> TableCreateStatement
     where
         E: EntityTrait,
     {
-        create_table_from_entity(entity, db_backend)
+        create_table_from_entity(entity, self.backend)
     }
 }
 
-pub(crate) fn create_enum_from_entity<E>(_: E, db_backend: DbBackend) -> Vec<TypeCreateStatement>
+pub(crate) fn create_enum_from_entity<E>(_: E, backend: DbBackend) -> Vec<TypeCreateStatement>
 where
     E: EntityTrait,
 {
-    if matches!(db_backend, DbBackend::MySql | DbBackend::Sqlite) {
+    if matches!(backend, DbBackend::MySql | DbBackend::Sqlite) {
         return Vec::new();
     }
     let mut vec = Vec::new();
@@ -52,7 +52,7 @@ where
     vec
 }
 
-pub(crate) fn create_table_from_entity<E>(entity: E, db_backend: DbBackend) -> TableCreateStatement
+pub(crate) fn create_table_from_entity<E>(entity: E, backend: DbBackend) -> TableCreateStatement
 where
     E: EntityTrait,
 {
@@ -61,7 +61,7 @@ where
     for column in E::Column::iter() {
         let orm_column_def = column.def();
         let types = match orm_column_def.col_type {
-            ColumnType::Enum(s, variants) => match db_backend {
+            ColumnType::Enum(s, variants) => match backend {
                 DbBackend::MySql => {
                     ColumnType::Custom(format!("ENUM('{}')", variants.join("', '")))
                 }
@@ -175,8 +175,10 @@ mod tests {
 
     #[test]
     fn test_create_table_from_entity() {
+        let schema = Schema::new(DbBackend::MySql);
         assert_eq!(
-            Schema::create_table_from_entity(CakeFillingPrice, DbBackend::MySql)
+            schema
+                .create_table_from_entity(CakeFillingPrice)
                 .to_string(MysqlQueryBuilder),
             Table::create()
                 .table(CakeFillingPrice)

src/schema/mod.rs

@@ -1,5 +1,17 @@
+use crate::DbBackend;
+
 mod entity;
 
-/// This structure defines a schema for a table
+/// This is a helper struct to convert [`EntityTrait`](crate::EntityTrait)
+/// into different [`sea_query`](crate::sea_query) statements.
 #[derive(Debug)]
-pub struct Schema;
+pub struct Schema {
+    backend: DbBackend,
+}
+
+impl Schema {
+    /// Create a helper for a specific database backend
+    pub fn new(backend: DbBackend) -> Self {
+        Self { backend }
+    }
+}

tests/common/setup/mod.rs

@@ -108,7 +108,9 @@ where
     }
 
     let expect_stmts: Vec<Statement> = creates.iter().map(|stmt| builder.build(stmt)).collect();
-    let create_from_entity_stmts: Vec<Statement> = Schema::create_enum_from_entity(entity, builder)
+    let schema = Schema::new(builder);
+    let create_from_entity_stmts: Vec<Statement> = schema
+        .create_enum_from_entity(entity)
         .iter()
         .map(|stmt| builder.build(stmt))
         .collect();
@@ -131,8 +133,9 @@ where
     E: EntityTrait,
 {
     let builder = db.get_database_backend();
+    let schema = Schema::new(builder);
     assert_eq!(
-        builder.build(&Schema::create_table_from_entity(entity, builder)),
+        builder.build(&schema.create_table_from_entity(entity)),
         builder.build(create)
     );
 

tests/crud/updates.rs

@@ -1,6 +1,6 @@
 pub use super::*;
 use rust_decimal_macros::dec;
-use sea_orm::DbErr;
+use sea_orm::{query::*, DbErr};
 use uuid::Uuid;
 
 pub async fn test_update_cake(db: &DbConn) {