manager.rs

use sea_orm::sea_query::{
    extension::postgres::{TypeAlterStatement, TypeCreateStatement, TypeDropStatement},
    ForeignKeyCreateStatement, ForeignKeyDropStatement, IndexCreateStatement, IndexDropStatement,
    TableAlterStatement, TableCreateStatement, TableDropStatement, TableRenameStatement,
    TableTruncateStatement,
};
use sea_orm::{ConnectionTrait, DbBackend, DbConn, DbErr, StatementBuilder};
use sea_schema::{mysql::MySql, postgres::Postgres, probe::SchemaProbe, sqlite::Sqlite};

/// Helper struct for writing migration scripts in migration file
pub struct SchemaManager<'c> {
    conn: &'c DbConn,
}

impl<'c> SchemaManager<'c> {
    pub fn new(conn: &'c DbConn) -> Self {
        Self { conn }
    }

    pub async fn exec_stmt<S>(&self, stmt: S) -> Result<(), DbErr>
    where
        S: StatementBuilder,
    {
        let builder = self.conn.get_database_backend();
        self.conn.execute(builder.build(&stmt)).await.map(|_| ())
    }

    pub fn get_database_backend(&self) -> DbBackend {
        self.conn.get_database_backend()
    }

    pub fn get_connection(&self) -> &'c DbConn {
        self.conn
    }
}

/// Schema Creation
impl<'c> SchemaManager<'c> {
    pub async fn create_table(&self, stmt: TableCreateStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn create_index(&self, stmt: IndexCreateStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn create_foreign_key(&self, stmt: ForeignKeyCreateStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn create_type(&self, stmt: TypeCreateStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }
}

/// Schema Mutation
impl<'c> SchemaManager<'c> {
    pub async fn alter_table(&self, stmt: TableAlterStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn drop_table(&self, stmt: TableDropStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn rename_table(&self, stmt: TableRenameStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn truncate_table(&self, stmt: TableTruncateStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn drop_index(&self, stmt: IndexDropStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn drop_foreign_key(&self, stmt: ForeignKeyDropStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn alter_type(&self, stmt: TypeAlterStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }

    pub async fn drop_type(&self, stmt: TypeDropStatement) -> Result<(), DbErr> {
        self.exec_stmt(stmt).await
    }
}

/// Schema Inspection
impl<'c> SchemaManager<'c> {
    pub async fn has_table<T>(&self, table: T) -> Result<bool, DbErr>
    where
        T: AsRef<str>,
    {
        let stmt = match self.conn.get_database_backend() {
            DbBackend::MySql => MySql::has_table(table),
            DbBackend::Postgres => Postgres::has_table(table),
            DbBackend::Sqlite => Sqlite::has_table(table),
        };

        let builder = self.conn.get_database_backend();
        let res = self
            .conn
            .query_one(builder.build(&stmt))
            .await?
            .ok_or_else(|| DbErr::Custom("Failed to check table exists".to_owned()))?;

        res.try_get("", "has_table")
    }

    pub async fn has_column<T, C>(&self, table: T, column: C) -> Result<bool, DbErr>
    where
        T: AsRef<str>,
        C: AsRef<str>,
    {
        let stmt = match self.conn.get_database_backend() {
            DbBackend::MySql => MySql::has_column(table, column),
            DbBackend::Postgres => Postgres::has_column(table, column),
            DbBackend::Sqlite => Sqlite::has_column(table, column),
        };

        let builder = self.conn.get_database_backend();
        let res = self
            .conn
            .query_one(builder.build(&stmt))
            .await?
            .ok_or_else(|| DbErr::Custom("Failed to check column exists".to_owned()))?;

        res.try_get("", "has_column")
    }
}