toql_core/sql_builder/
select_stream.rs

1//! Deserializing selected columns into struct fields.
2
3/// Hold select state about a struct field.
4#[derive(Debug, PartialEq)]
5pub enum Select {
6    /// Field is selected in the query
7    Query,
8    /// Field is always selected (preselection)
9    Preselect,
10    /// Field is not selected
11    None,
12}
13
14impl Select {
15    /// Return true, if field is selected
16    pub fn is_selected(&self) -> bool {
17        self != &Select::None
18    }
19}
20
21/// SelectStream memorizes which fields and joined structs are selected.
22///
23/// It is needed for the deserialization trait [FromRow](crate::from_row::FromRow).
24/// The selections can either come from the query or the preselections in the mapping.
25/// The number of selections does not correspond with the number of selected columns or expressions, because
26/// each join gets an additional selection. For the number of columns take (BuildResult::column_counter)[crate::sql_builder::build_result::BuildResult::column_counter].
27#[derive(Debug, PartialEq)]
28pub struct SelectStream {
29    stream: Vec<Select>,
30}
31
32impl SelectStream {
33    /// Create new stream.
34    pub fn new() -> Self {
35        Self { stream: Vec::new() }
36    }
37    /// Add select state at the end of the stream.
38    pub fn push(&mut self, selection: Select) {
39        self.stream.push(selection);
40    }
41    /// Return iterator to the stream.
42    pub fn iter(&self) -> std::slice::Iter<'_, Select> {
43        self.stream.iter()
44    }
45}
46
47impl Default for SelectStream {
48    fn default() -> Self {
49        Self::new()
50    }
51}
52
53#[cfg(test)]
54mod test {
55    use super::SelectStream;
56
57    #[test]
58    fn default() {
59        assert_eq!(SelectStream::new(), SelectStream::default())
60    }
61}
toql_core/sql_builder/select_stream.rs

toql_core/sql_builder/
select_stream.rs
