surrealdb_core/sql/statements/
delete.rs

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use crate::ctx::{Context, MutableContext};
use crate::dbs::{Iterator, Options, Statement};
use crate::doc::CursorDoc;
use crate::err::Error;
use crate::sql::{Cond, Output, Timeout, Value, Values};
use derive::Store;
use reblessive::tree::Stk;
use revision::revisioned;
use serde::{Deserialize, Serialize};
use std::fmt;

#[revisioned(revision = 2)]
#[derive(Clone, Debug, Default, Eq, PartialEq, PartialOrd, Serialize, Deserialize, Store, Hash)]
#[cfg_attr(feature = "arbitrary", derive(arbitrary::Arbitrary))]
#[non_exhaustive]
pub struct DeleteStatement {
	#[revision(start = 2)]
	pub only: bool,
	pub what: Values,
	pub cond: Option<Cond>,
	pub output: Option<Output>,
	pub timeout: Option<Timeout>,
	pub parallel: bool,
}

impl DeleteStatement {
	/// Check if we require a writeable transaction
	pub(crate) fn writeable(&self) -> bool {
		true
	}
	/// Process this type returning a computed simple Value
	pub(crate) async fn compute(
		&self,
		stk: &mut Stk,
		ctx: &Context,
		opt: &Options,
		doc: Option<&CursorDoc>,
	) -> Result<Value, Error> {
		// Valid options?
		opt.valid_for_db()?;
		// Create a new iterator
		let mut i = Iterator::new();
		// Assign the statement
		let stm = Statement::from(self);
		// Ensure futures are stored
		let opt = &opt.new_with_futures(false);
		// Check if there is a timeout
		let ctx = match self.timeout.as_ref() {
			Some(timeout) => {
				let mut ctx = MutableContext::new(ctx);
				ctx.add_timeout(*timeout.0)?;
				ctx.freeze()
			}
			None => ctx.clone(),
		};
		// Loop over the delete targets
		for w in self.what.0.iter() {
			let v = w.compute(stk, &ctx, opt, doc).await?;
			i.prepare(&stm, v).map_err(|e| match e {
				Error::InvalidStatementTarget {
					value: v,
				} => Error::DeleteStatement {
					value: v,
				},
				e => e,
			})?;
		}
		// Process the statement
		let res = i.output(stk, &ctx, opt, &stm).await?;
		// Catch statement timeout
		if ctx.is_timedout() {
			return Err(Error::QueryTimedout);
		}
		// Output the results
		match res {
			// This is a single record result
			Value::Array(mut a) if self.only => match a.len() {
				// There was exactly one result
				1 => Ok(a.remove(0)),
				// There were no results
				_ => Err(Error::SingleOnlyOutput),
			},
			// This is standard query result
			v => Ok(v),
		}
	}
}

impl fmt::Display for DeleteStatement {
	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
		write!(f, "DELETE")?;
		if self.only {
			f.write_str(" ONLY")?
		}
		write!(f, " {}", self.what)?;
		if let Some(ref v) = self.cond {
			write!(f, " {v}")?
		}
		if let Some(ref v) = self.output {
			write!(f, " {v}")?
		}
		if let Some(ref v) = self.timeout {
			write!(f, " {v}")?
		}
		if self.parallel {
			f.write_str(" PARALLEL")?
		}
		Ok(())
	}
}