Struct native_db::transaction::query::RGet

pub struct RGet<'db, 'txn> { /* private fields */ }

Get a value from the database.

Implementations

impl RGet<'_, '_>

pub fn primary<T: Input>(&self, key: impl InnerKeyValue) -> Result<Option<T>>

Get a value from the database by primary key.

Example

use native_db::*;
use native_model::{native_model, Model};
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
#[native_model(id=1, version=1)]
#[native_db]
struct Data {
    #[primary_key]
    id: u64,
}

fn main() -> Result<(), db_type::Error> {
    let mut builder = DatabaseBuilder::new();
    builder.define::<Data>()?;
    let db = builder.create_in_memory()?;
     
    // Open a read transaction
    let r = db.r_transaction()?;
     
    // Get a value by primary key
    let _value: Option<Data> = r.get().primary(1u64)?;
    Ok(())
}

pub fn secondary<T: Input>( &self, key_def: impl KeyDefinition<DatabaseSecondaryKeyOptions>, key: impl InnerKeyValue ) -> Result<Option<T>>

Get a value from the database by secondary key.

/!\ The secondary key must be unique else this method will return an error SecondaryKeyConstraintMismatch. If the secondary key is not unique, use scan() instead.

Anatomy of a secondary key it is a enum with the following structure: <table_name>Key::<name>.

Example

use native_db::*;
use native_model::{native_model, Model};
use serde::{Deserialize, Serialize};

#[derive(Serialize, Deserialize)]
#[native_model(id=1, version=1)]
#[native_db]
struct Data {
    #[primary_key]
    id: u64,
    #[secondary_key(unique)] // Must be unique to use get()
    name: String,
}

fn main() -> Result<(), db_type::Error> {
    let mut builder = DatabaseBuilder::new();
    builder.define::<Data>()?;
    let db = builder.create_in_memory()?;
     
    // Open a read transaction
    let r = db.r_transaction()?;
     
    // Get a value by primary key
    let _value: Option<Data> = r.get().secondary(DataKey::name, "test")?;
    Ok(())
}