Struct Cycle

pub struct Cycle {
    pub(crate) expr: Option<Expr>,
    pub(crate) set_as: Option<DynIden>,
    pub(crate) using: Option<DynIden>,
}

For recursive WithQuery WithClauses the CYCLE sql clause can be specified to avoid creating an infinite traversals that loops on graph cycles indefinitely.

You specify an expression that identifies a node in the graph, which is used during the query execution iteration, to determine newly appended values are distinct new nodes or are already visited, and therefore they should be added into the result again.

A query can have both SEARCH and CYCLE clauses.

Setting Self::set, Self::expr and Self::using is mandatory.

Fields

expr: Option<Expr>

set_as: Option<DynIden>

using: Option<DynIden>

Implementations

impl Cycle

pub fn new_from_expr_set_using<EXPR, ID1, ID2>( expr: EXPR, set: ID1, using: ID2, ) -> Self

where EXPR: Into<Expr>, ID1: IntoIden, ID2: IntoIden,

Create a complete Search specification from the SearchOrder and a SelectExpr. The given SelectExpr must have an alias specified.

pub fn new() -> Self

Constructs a new empty Cycle.

pub fn expr<EXPR>(&mut self, expr: EXPR) -> &mut Self

where EXPR: Into<Expr>,

The expression identifying nodes.

pub fn set<ID>(&mut self, set: ID) -> &mut Self

where ID: IntoIden,

The name of the boolean column containing whether we have completed a cycle or not yet generated by this clause.

pub fn using<ID>(&mut self, using: ID) -> &mut Self

where ID: IntoIden,

The name of the array typed column that contains the node ids (generated using the Self::expr) that specify the current nodes path that will be generated by this clause.

Trait Implementations

impl Clone for Cycle

fn clone(&self) -> Cycle

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Cycle

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Cycle

fn default() -> Cycle

Returns the “default value” for a type.

impl PartialEq for Cycle

fn eq(&self, other: &Cycle) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Cycle