多对多tag的处理

app.sql

@@ -50,3 +50,28 @@ VALUES (1, '标题-GLKUSroPOR', '内容-GLKUSroPOR'),
        (1, '标题-svNJmWaqRo', '内容-svNJmWaqRo'),
        (3, '标题-8XWiTUSfhB', '内容-8XWiTUSfhB'),
        (2, '标题-yvwE32TLkg', '内容-yvwE32TLkg');
+
+
+CREATE TABLE tags
+(
+    id   int unsigned PRIMARY KEY AUTO_INCREMENT,
+    name VARCHAR(20) NOT NULL UNIQUE
+);
+
+INSERT INTO tags (name)
+VALUES ('标签1'),
+       ('标签2'),
+       ('标签3');
+
+CREATE TABLE article_tags
+(                                                       -- 文章标签
+    id         int unsigned PRIMARY KEY AUTO_INCREMENT, -- 自增主键
+    article_id INT NOT NULL REFERENCES articles (id),
+    tag_id     INT NOT NULL REFERENCES tags (id)
+);
+INSERT INTO article_tags(article_id, tag_id)
+VALUES (1, 1),
+       (2, 1),
+       (2, 2),
+       (3, 1),
+       (1, 3);

src/entity/article.rs

@@ -44,6 +44,19 @@ impl Related<super::category::Entity> for Entity {
     }
 }
 
+
+impl Related<super::tag::Entity> for Entity {
+    fn to() -> RelationDef {
+        super::article_tag::Relation::Tag.def()
+    }
+
+    fn via() -> Option<RelationDef> {
+        Some(super::article_tag::Relation::Article.def().rev())
+    }
+}
+
+
+
 // INSERT/UPDATE/DELETE 等属于写操作，需使用 ActiveModel。
 /// [DeriveEntityModel] 这个 derive 根据我们定义的[Model]，生成了包括 [ActiveModel]在内的多个数据结构
 impl ActiveModelBehavior for ActiveModel {}

src/entity/article_tag.rs

@@ -0,0 +1,39 @@
+use sea_orm::entity::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, PartialEq, DeriveEntityModel, Serialize, Deserialize)]
+#[sea_orm(table_name = "article_tags")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    #[serde(skip_deserializing)]
+    pub id: u32,
+    pub article_id: u32,
+    pub tag_id: u32,
+}
+
+#[derive(Debug, Clone, Copy, EnumIter)]
+pub enum Relation {
+    Article,
+    Tag,
+}
+
+impl RelationTrait for Relation {
+    fn def(&self) -> RelationDef {
+        match self {
+            Relation::Article => Entity::belongs_to(super::article::Entity)
+                .from(Column::ArticleId)
+                .to(super::article::Column::Id)
+                .into(),
+            Relation::Tag => Entity::belongs_to(super::tag::Entity)
+                .from(Column::TagId)
+                .to(super::tag::Column::Id)
+                .into(),
+        }
+    }
+}
+
+
+impl ActiveModelBehavior for ActiveModel {}
+
+
+

src/entity/mod.rs

@@ -1,2 +1,4 @@
 pub mod category;
 pub mod article;
+pub mod article_tag;
+pub mod tag;

src/entity/tag.rs

@@ -0,0 +1,40 @@
+use sea_orm::entity::prelude::*;
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, PartialEq, DeriveEntityModel, Serialize, Deserialize)]
+#[sea_orm(table_name = "tags")]
+pub struct Model {
+    #[sea_orm(primary_key)]
+    #[serde(skip_deserializing)]
+    pub id: u32,
+    pub name: String,
+}
+
+#[derive(Debug, Clone, Copy, EnumIter)]
+pub enum Relation {}
+
+impl RelationTrait for Relation {
+    fn def(&self) -> RelationDef {
+        panic!()
+    }
+}
+
+// 没有给标签实体定义关系，而是通过 Related<super::article::Entity>告诉 SeaORM如何去找所需要的文章实体。
+impl Related<super::article::Entity> for Entity {
+    // 某个实体是否与另一个实体相关
+    fn to()-> RelationDef {
+        super::article_tag::Relation::Article.def()
+    }
+
+    // 某个实体是否通过另一个实体关联 即tag通过article_tag进行关联
+    // 表示通过标签实体关联到某个实体的关系，通过 Tag 的反向关系定义进行关联。
+    fn via() -> Option<RelationDef> {
+        Some(super::article_tag::Relation::Tag.def().rev())
+    }
+}
+
+
+impl ActiveModelBehavior for ActiveModel {}
+
+
+

src/handler/article.rs

@@ -5,7 +5,7 @@ use axum::Form;
 use sea_orm::{ActiveModelTrait, ColumnTrait, Condition, EntityTrait, NotSet, PaginatorTrait, QueryFilter, QueryOrder, QuerySelect};
 use sea_orm::ActiveValue::Set;
 
-use crate::entity::{article, category};
+use crate::entity::{article, category, tag};
 use crate::err::AppError;
 use crate::form::ArticleForm;
 use crate::handler::{get_conn, HtmlResponse, log_error, redirect, RedirectResponse, render};
@@ -96,3 +96,35 @@ pub async fn add(
 
     redirect("/article?msg=文章添加成功")
 }
+
+pub async fn list_with_tags( State(state): State<Arc<AppState>>) -> Result<String>  {
+    let handler_name = "article/list_with_tags";
+    let conn = get_conn(&state);
+
+    let list = article::Entity::find()
+        .find_with_related(tag::Entity)
+        .all(conn)
+        .await
+        .map_err(AppError::from)
+        .map_err(log_error(handler_name))?;
+
+    let mut ss = vec![];
+
+    for item in list {
+        let (article, tags) = item;
+        let tags = tags
+            .iter()
+            .map(|tag| format!("【#{} - {}】", &tag.id, &tag.name))
+            .collect::<Vec<String>>()
+            .join(",")
+            .to_string();
+
+        let s = format!(
+            "文章ID: {}, 文章标题: {}, 标签： {}",
+            &article.id, &article.title, tags,
+        );
+        ss.push(s);
+    }
+
+    Ok(ss.join("\n").to_string())
+}

src/router.rs

@@ -20,7 +20,8 @@ pub fn init() -> axum::Router<Arc<AppState>> {
 
     let article_router = axum::Router::new()
         .route("/", get(handler::article::index))
-        .route("/add", get(handler::article::add_ui).post(handler::article::add));
+        .route("/add", get(handler::article::add_ui).post(handler::article::add))
+        .route("/tags", get(handler::article::list_with_tags));
 
     axum::Router::new()
         .route("/", get(handler::index))