Struct Projection

pub struct Projection { /* private fields */ }

Projection is a definition of field mapping during a query. Fields come from one or several source structures (can be tables, views or sub queries) and are mapped to a Query as output.

Implementations

impl Projection

pub fn new(fields: Vec<ProjectionField>) -> Self

Instantiate a new Projection

pub fn from(fields: &[(&str, &str, &str)]) -> Self

Create a Projection from a list of tuples &[(name, definition, sql_type)].

pub fn add_field( &mut self, field_name: &str, definition: &str, output_type: &str, )

Add a new field to the definition. This is one of the projection building tool to create a projection out of an existing structure. This is a blanket implementation.

pub fn get_fields(&self) -> &Vec<ProjectionField>

Returns the list of the ProjectionFields of this Projection.

pub fn expand(&self, aliases: SourceAlias) -> String

Turn the Projection into a string suitable for use in SQL queries.

Trait Implementations

impl Default for Projection

fn default() -> Self

Returns the “default value” for a type.