vantage_table/references/
one.rs

1//! HasOne — one-to-one relationship where the foreign key is on the source table.
2//!
3//! Example: Client has one Bakery (via client.bakery_id)
4
5use std::fmt::Display;
6use std::{any::Any, marker::PhantomData, sync::Arc};
7
8use vantage_core::{Result, error};
9use vantage_types::{EmptyEntity, Entity, Record};
10use vantage_vista::{JoinKey, Reference as VistaReference};
11
12use crate::{references::Reference, table::Table, traits::table_source::TableSource};
13
14pub struct HasOne<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> {
15    /// Foreign key column on the source table (e.g. "bakery_id")
16    foreign_key: String,
17    /// Factory: given a data source, produce the target table
18    build_target: Arc<dyn Fn(T) -> Table<T, TargetE> + Send + Sync>,
19    _phantom: PhantomData<SourceE>,
20}
21
22impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>>
23    HasOne<T, SourceE, TargetE>
24{
25    pub fn new(
26        foreign_key: impl Into<String>,
27        build_target: impl Fn(T) -> Table<T, TargetE> + Send + Sync + 'static,
28    ) -> Self {
29        Self {
30            foreign_key: foreign_key.into(),
31            build_target: Arc::new(build_target),
32            _phantom: PhantomData,
33        }
34    }
35}
36
37impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> Clone
38    for HasOne<T, SourceE, TargetE>
39{
40    fn clone(&self) -> Self {
41        Self {
42            foreign_key: self.foreign_key.clone(),
43            build_target: self.build_target.clone(),
44            _phantom: PhantomData,
45        }
46    }
47}
48
49impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> std::fmt::Debug
50    for HasOne<T, SourceE, TargetE>
51{
52    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
53        f.debug_struct("HasOne")
54            .field("foreign_key", &self.foreign_key)
55            .finish()
56    }
57}
58
59impl<
60    T: TableSource + 'static,
61    SourceE: Entity<T::Value> + 'static,
62    TargetE: Entity<T::Value> + 'static,
63> Reference for HasOne<T, SourceE, TargetE>
64where
65    T::Value: Into<ciborium::Value> + From<ciborium::Value>,
66    T::Id: Display + From<String>,
67{
68    fn columns(&self, _source_id: &str, target_id: &str) -> (String, String) {
69        (self.foreign_key.clone(), target_id.to_string())
70    }
71
72    fn vista_reference(&self, name: &str, target: String, _source_id: &str) -> VistaReference {
73        VistaReference::has_one(name, target, JoinKey::to_target_id(&self.foreign_key))
74    }
75
76    fn build_target(&self, data_source: &dyn Any) -> Box<dyn Any> {
77        let ds = data_source
78            .downcast_ref::<T>()
79            .expect("data source type mismatch in HasOne::build_target");
80        Box::new((self.build_target)(ds.clone()))
81    }
82
83    fn build_target_erased(&self, data_source: &dyn Any) -> Box<dyn Any> {
84        let ds = data_source
85            .downcast_ref::<T>()
86            .expect("data source type mismatch in HasOne::build_target_erased");
87        Box::new((self.build_target)(ds.clone()).into_entity::<EmptyEntity>())
88    }
89
90    fn resolve_from_row(
91        &self,
92        data_source: &dyn Any,
93        _source_id_field: &str,
94        source_row: &dyn Any,
95    ) -> Result<Box<dyn Any>> {
96        let ds = data_source
97            .downcast_ref::<T>()
98            .ok_or_else(|| error!("data source type mismatch in HasOne::resolve_from_row"))?;
99        let row = source_row
100            .downcast_ref::<Record<T::Value>>()
101            .ok_or_else(|| error!("source row type mismatch in HasOne::resolve_from_row"))?;
102
103        let mut target = (self.build_target)(ds.clone());
104        let target_id = target.id_field_name();
105
106        let (src_col, tgt_col) = self.columns("", &target_id);
107        let join_value = row.get(&src_col).cloned().ok_or_else(|| {
108            error!(
109                "source row missing foreign-key field",
110                field = src_col.as_str()
111            )
112        })?;
113        // Rows arriving from a script/JSON surface carry ids in string form.
114        let join_value = ds.coerce_reference_value(join_value);
115
116        let condition = ds.eq_value_condition(&tgt_col, join_value.clone())?;
117        target.add_condition(condition);
118        // Conform inserts into the single-target set to the join value.
119        target.add_invariant(tgt_col, join_value);
120
121        Ok(Box::new(target.into_entity::<EmptyEntity>()))
122    }
123
124    fn target_table_name(&self, data_source: &dyn Any) -> String {
125        let ds = data_source
126            .downcast_ref::<T>()
127            .expect("data source type mismatch in HasOne::target_table_name");
128        (self.build_target)(ds.clone()).table_name().to_string()
129    }
130}
vantage_table/references/one.rs

vantage_table/references/
one.rs
