nene

nene is a command-line tool to generate Rust code for Google Cloud Spanner.
nene uses database schema to generate code by using Information Schema. nene runs SQL queries against tables in INFORMATION_SCHEMA to fetch metadata for a database, and applies the metadata to Go templates to generate code/models to acccess Cloud Spanner.

Installation

cargo install nene

Usage

export RUST_LOG=info
export SPANNER_DSN=projects/local-project/instances/test-instance/databases/local-database
# if you don't use emulator use GOOGLE_APPLICATION_CREDENTIALS instead of SPANNER_EMULATOR_HOST
export SPANNER_EMULATOR_HOST=localhost:9010 
mkdir ./gen
nene -o ./gen

• -i

  • template directory.
  • see template directory structure
  • if not specified default template are used.

• -o

  • output directory
  • default directory is ./gen

Generated file with default template

Default template generates the files for google-cloud-spanner.

// DON'T EDIT. this code is generated by nene.
use google_cloud_googleapis::spanner::v1::Mutation;
use google_cloud_gax::grpc::Status;
use google_cloud_spanner::client::{RunInTxError, TxError};
use google_cloud_spanner::key::Key;
use google_cloud_spanner::mutation::{
  delete, insert_or_update_struct, insert_struct, replace_struct, update_struct,
};
use google_cloud_spanner::reader::AsyncIterator;
use google_cloud_spanner::row::{Error as RowError, Row, Struct, TryFromStruct};
use google_cloud_spanner::statement::{Kinds, Statement, ToKind, ToStruct, Types};
use google_cloud_spanner::transaction::Transaction;
use google_cloud_spanner::transaction::CallOptions;
use google_cloud_spanner::value::CommitTimestamp;
use std::convert::TryFrom;

pub const TABLE_NAME: &str = "User";
pub const COLUMN_USER_ID: &str = "UserId";
pub const COLUMN_PREMIUM: &str = "Premium";
pub const COLUMN_UPDATED_AT: &str = "UpdatedAt";

pub struct User {
  pub user_id: String,
  pub premium: bool,
  pub updated_at: chrono::DateTime<chrono::Utc>,
}

impl User {
  pub fn insert(&self) -> Mutation {
    insert_struct(TABLE_NAME, &self)
  }

  pub fn update(&self) -> Mutation {
    update_struct(TABLE_NAME, &self)
  }

  pub fn replace(&self) -> Mutation {
    replace_struct(TABLE_NAME, &self)
  }

  pub fn insert_or_update(&self) -> Mutation {
    insert_or_update_struct(TABLE_NAME, &self)
  }

  pub fn delete(&self) -> Mutation {
    delete(TABLE_NAME, Key::key(&self.user_id))
  }

  pub async fn find_by_pk(
    tx: &mut Transaction, user_id: &String, options: Option<CallOptions>
  ) -> Result<Option<Self>, RunInTxError> {
    let mut stmt = Statement::new("SELECT * From User WHERE UserId = @UserId");
    stmt.add_param(COLUMN_USER_ID, user_id);
    let mut rows = Self::read_by_statement(tx, stmt, options).await?;
    if !rows.is_empty() {
      Ok(rows.pop())
    } else {
      Ok(None)
    }
  }

  pub async fn read_by_statement(
    tx: &mut Transaction,
    stmt: Statement,
    options: Option<CallOptions>
  ) -> Result<Vec<Self>, RunInTxError> {
    let mut reader = tx.query(stmt).await?;
    if options.is_some() {
      reader.set_call_options(options.unwrap());
    }
    let mut result = vec![];
    while let Some(row) = reader.next().await? {
      let data = Self::try_from(row)?;
      result.push(data)
    }
    Ok(result)
  }
}

impl ToStruct for User {
  fn to_kinds(&self) -> Kinds {
    vec![
      (COLUMN_USER_ID, self.user_id.to_kind()),
      (COLUMN_PREMIUM, self.premium.to_kind()),
      (COLUMN_UPDATED_AT, CommitTimestamp::new().to_kind()),
    ]
  }

  fn get_types() -> Types {
    vec![
      (COLUMN_USER_ID, String::get_type()),
      (COLUMN_PREMIUM, bool::get_type()),
      (COLUMN_UPDATED_AT, CommitTimestamp::get_type()),
    ]
  }
}

impl TryFromStruct for User {
  fn try_from_struct(s: Struct<'_>) -> Result<Self, RowError> {
    Ok(User {
      user_id: s.column_by_name(COLUMN_USER_ID)?,
      premium: s.column_by_name(COLUMN_PREMIUM)?,
      updated_at: s.column_by_name(COLUMN_UPDATED_AT)?,
    })
  }
}

impl TryFrom<Row> for User {
  type Error = RowError;
  fn try_from(row: Row) -> Result<Self, RowError> {
    Ok(User {
      user_id: row.column_by_name(COLUMN_USER_ID)?,
      premium: row.column_by_name(COLUMN_PREMIUM)?,
      updated_at: row.column_by_name(COLUMN_UPDATED_AT)?,
    })
  }
}