vantage_table/references/
many.rs

1//! HasMany — one-to-many relationship where the foreign key is on the target table.
2//!
3//! Example: Bakery has many Clients (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};
10
11use crate::{
12    any::AnyTable,
13    references::Reference,
14    table::Table,
15    traits::{column_like::ColumnLike, table_source::TableSource},
16};
17
18pub struct HasMany<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> {
19    /// Foreign key column on the target table (e.g. "bakery_id" on client)
20    target_foreign_key: String,
21    /// Factory: given a data source, produce the target table
22    build_target: Arc<dyn Fn(T) -> Table<T, TargetE> + Send + Sync>,
23    _phantom: PhantomData<SourceE>,
24}
25
26impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>>
27    HasMany<T, SourceE, TargetE>
28{
29    pub fn new(
30        target_foreign_key: impl Into<String>,
31        build_target: impl Fn(T) -> Table<T, TargetE> + Send + Sync + 'static,
32    ) -> Self {
33        Self {
34            target_foreign_key: target_foreign_key.into(),
35            build_target: Arc::new(build_target),
36            _phantom: PhantomData,
37        }
38    }
39}
40
41impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> Clone
42    for HasMany<T, SourceE, TargetE>
43{
44    fn clone(&self) -> Self {
45        Self {
46            target_foreign_key: self.target_foreign_key.clone(),
47            build_target: self.build_target.clone(),
48            _phantom: PhantomData,
49        }
50    }
51}
52
53impl<T: TableSource, SourceE: Entity<T::Value>, TargetE: Entity<T::Value>> std::fmt::Debug
54    for HasMany<T, SourceE, TargetE>
55{
56    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
57        f.debug_struct("HasMany")
58            .field("target_foreign_key", &self.target_foreign_key)
59            .finish()
60    }
61}
62
63impl<
64    T: TableSource + 'static,
65    SourceE: Entity<T::Value> + 'static,
66    TargetE: Entity<T::Value> + 'static,
67> Reference for HasMany<T, SourceE, TargetE>
68where
69    T::Value: Into<ciborium::Value> + From<ciborium::Value>,
70    T::Id: Display + From<String>,
71{
72    fn columns(&self, source_id: &str, _target_id: &str) -> (String, String) {
73        (source_id.to_string(), self.target_foreign_key.clone())
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 HasMany::build_target");
80        Box::new((self.build_target)(ds.clone()))
81    }
82
83    fn cardinality(&self) -> vantage_vista::ReferenceKind {
84        vantage_vista::ReferenceKind::HasMany
85    }
86
87    fn resolve_from_row(
88        &self,
89        data_source: &dyn Any,
90        source_id_field: &str,
91        source_row: &dyn Any,
92    ) -> Result<Box<dyn Any>> {
93        let ds = data_source
94            .downcast_ref::<T>()
95            .ok_or_else(|| error!("data source type mismatch in HasMany::resolve_from_row"))?;
96        let row = source_row
97            .downcast_ref::<Record<T::Value>>()
98            .ok_or_else(|| error!("source row type mismatch in HasMany::resolve_from_row"))?;
99
100        let mut target = (self.build_target)(ds.clone());
101        let (src_col, tgt_col) = self.columns(source_id_field, "");
102        let join_value = row
103            .get(&src_col)
104            .cloned()
105            .ok_or_else(|| error!("source row missing id field", field = src_col.as_str()))?;
106
107        let condition = ds.eq_value_condition(&tgt_col, join_value)?;
108        target.add_condition(condition);
109
110        Ok(Box::new(target.into_entity::<EmptyEntity>()))
111    }
112
113    fn resolve_as_any(&self, source_table: &dyn Any) -> Result<AnyTable> {
114        let source = source_table
115            .downcast_ref::<Table<T, SourceE>>()
116            .ok_or_else(|| {
117                vantage_core::error!("Source table type mismatch in HasMany::resolve_as_any")
118            })?;
119
120        let source_id = source
121            .id_field()
122            .map(|c| c.name().to_string())
123            .unwrap_or_else(|| "id".to_string());
124
125        let mut target = (self.build_target)(source.data_source().clone());
126
127        let target_id = target
128            .id_field()
129            .map(|c| c.name().to_string())
130            .unwrap_or_else(|| "id".to_string());
131
132        let (src_col, tgt_col) = self.columns(&source_id, &target_id);
133        let condition = source
134            .data_source()
135            .related_in_condition(&tgt_col, source, &src_col);
136        target.add_condition(condition);
137
138        Ok(AnyTable::from_table(target))
139    }
140
141    fn target_type_name(&self) -> &'static str {
142        std::any::type_name::<Table<T, TargetE>>()
143    }
144}
vantage_table/references/many.rs

vantage_table/references/
many.rs
