Struct migration::Cycle

pub struct Cycle { /* private fields */ }

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 and that will be used to determine during the iteration of the execution of the query when appending of new values whether the new values are distinct new nodes or are already visited and therefore they should be added again into the result.

A query can have both SEARCH and CYCLE clauses.

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

Implementations

impl Cycle

pub fn new_from_expr_set_using<EXPR, ID1, ID2>( expr: EXPR, set: ID1, using: ID2 ) -> Cyclewhere EXPR: Into<SimpleExpr>, 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() -> Cycle

Constructs a new empty Cycle.

pub fn expr<EXPR>(&mut self, expr: EXPR) -> &mut Cyclewhere EXPR: Into<SimpleExpr>,

The expression identifying nodes.

pub fn set<ID>(&mut self, set: ID) -> &mut Cyclewhere 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 Cyclewhere 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 copy 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<(), Error>

Formats the value using the given formatter.

impl Default for Cycle

fn default() -> Cycle

Returns the “default value” for a type.