tablo_core/resource/
relation.rs

1//! Relation tables: a record page's related rows through the related resource's own list table.
2
3use std::{any::TypeId, sync::Arc};
4
5use toasty::stmt::{Expr, IntoExpr, Path};
6
7use super::Resource;
8use crate::{form::FormScalar, schema::ResolvedLens, toasty_compat::pk};
9
10/// One relation of a parent resource's records.
11///
12/// Declared by [`ResourceDef::relation`](super::ResourceDef::relation); the related resource
13/// must be registered on the same panel, which keys the relation by its slug:
14///
15/// ```text
16/// ResourceDef::new().relation(Relation::has_many::<CommentResource>(Comment::fields().post_id()))
17/// ```
18pub struct Relation<P> {
19    pub(crate) child: TypeId,
20    pub(crate) child_name: &'static str,
21    pub(crate) label: Option<String>,
22    pub(crate) foreign_key: String,
23    bind: BindFn<P>,
24    pub(crate) scope_of: ScopeFn,
25    /// Why `foreign_key` binds no column, when it does not.
26    pub(crate) misdeclared: Option<crate::DeclarationErrorKind>,
27}
28
29/// An owner's rows filter on the child.
30type BindFn<P> = Arc<dyn Fn(&P) -> (Expr<bool>, String) + Send + Sync>;
31
32/// The child's rows that belong to the owner whose primary key a request names as text.
33pub(crate) type ScopeFn = Arc<dyn Fn(&str) -> Option<Expr<bool>> + Send + Sync>;
34
35/// A foreign-key column type referencing a primary key of type `K`: `K` itself, or `Option<K>`
36/// for an optional reference. Sealed: these are the only two.
37pub trait ForeignKey<K>:
38    sealed::Sealed<K> + IntoExpr<Self> + FormScalar + Send + Sync + 'static
39{
40}
41
42impl<K> ForeignKey<K> for K where K: IntoExpr<K> + FormScalar + Send + Sync + 'static {}
43
44impl<K> ForeignKey<K> for Option<K> where
45    Option<K>: IntoExpr<Self> + FormScalar + Send + Sync + 'static
46{
47}
48
49mod sealed {
50    pub trait Sealed<K> {}
51
52    impl<K> Sealed<K> for K {}
53
54    impl<K> Sealed<K> for Option<K> {}
55}
56
57impl<P> Relation<P>
58where
59    P: toasty::schema::Model + IntoExpr<P> + 'static,
60{
61    /// Declare a `has_many` child resource whose `foreign_key` holds the owner's primary key, a
62    /// single column.
63    ///
64    /// ```text
65    /// Relation::has_many::<CommentResource>(Comment::fields().post_id())
66    /// ```
67    pub fn has_many<C>(foreign_key: Path<C::Model, impl ForeignKey<P::PrimaryKey>>) -> Self
68    where
69        C: Resource,
70    {
71        Self::bound_by::<C, _>(foreign_key)
72    }
73
74    fn bound_by<C, T>(foreign_key: Path<C::Model, T>) -> Self
75    where
76        C: Resource,
77        T: ForeignKey<P::PrimaryKey>,
78    {
79        let binding = ResolvedLens::of(foreign_key.clone());
80        let scope_key = foreign_key.clone();
81        Self {
82            child: TypeId::of::<C>(),
83            child_name: std::any::type_name::<C>(),
84            label: None,
85            foreign_key: binding.name,
86            misdeclared: binding.misdeclared,
87            bind: Arc::new(move |owner| {
88                let scope = foreign_key.clone().eq(pk::pk_expr::<P, T>(owner));
89                (scope, pk::pk_text(owner))
90            }),
91            scope_of: Arc::new(move |owner| {
92                let owner = T::parse_form(owner.trim()).ok()?;
93                Some(scope_key.clone().eq(owner))
94            }),
95        }
96    }
97}
98
99impl<P> Relation<P> {
100    /// Titles the section `label` instead of the related resource's plural label.
101    #[must_use]
102    pub fn label(mut self, label: impl Into<String>) -> Self {
103        self.label = Some(label.into());
104        self
105    }
106
107    /// The child's rows that belong to `owner`, and the owner's primary key as text.
108    pub(crate) fn bind(&self, owner: &P) -> (Expr<bool>, String) {
109        (self.bind)(owner)
110    }
111}
112
113impl<P> std::fmt::Debug for Relation<P> {
114    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
115        f.debug_struct("Relation")
116            .field("child", &self.child_name)
117            .field("label", &self.label)
118            .field("foreign_key", &self.foreign_key)
119            .finish_non_exhaustive()
120    }
121}
tablo_core/resource/relation.rs

tablo_core/resource/
relation.rs
