【Vapor】10 Chapter 10：Sibling Relationships

0x00 Chapter 10：Sibling Relationships

6.To actually create a relationship between two models
you need to use the pivot
Fluent provides convenience functions for creating and removing relationships

First, open Acronym.swift and add a new property to the model below
var user: User:

    @Siblings(
        through: AcronymCategoryPivot.self,
        from: \.$acronym,
        to: \.$category
    )
    var categories: [Category]

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7.Open AcronymsController.swift and add the following route handler below
getUserHandler(_:) to set up the relationship between an acronym and a category

    // http://127.0.0.1:8080/api/acronyms/<acronymID>/categories/<categoryID>
    func addCategoriesHandler(_ req: Request) throws -> EventLoopFuture<HTTPStatus> {
        let acronymQuery = Acronym.find(req.parameters.get("acronymID"), on: req.db)
            .unwrap(or: Abort(.notFound))
        let categoryQuery = Category.find(req.parameters.get("categoryID"), on: req.db)
            .unwrap(or: Abort(.notFound))
        return acronymQuery.and(categoryQuery)
            .flatMap { acronym, category in
                acronym.$categories
                    .attach(category, on: req.db)
                    .transform(to: .created)
            }
    }

Register this route handler at the bottom of boot(routes:)

acronymsRoutes.post(":acronymID", "categories",  ":categoryID", use: addCategoriesHandler)

提交数据
url：http://127.0.0.1:8080/api/acronyms/<acronymID>/categories/<categoryID>
method：POST
parameter：无
成功后返回的状态码是：HTTP/1.1 201 Created

---

8.Acronym’s categories
Open AcronymsController.swift and add a new route handler after addCategoriesHandler(:_)

    // http://127.0.0.1:8080/api/acronyms/<acronymID>/categories
    func getCategoriesHandler(_ req: Request) throws -> EventLoopFuture<[Category]> {
        Acronym.find(req.parameters.get("acronymID"), on: req.db)
            .unwrap(or: Abort(.notFound))
            .flatMap { acronym in
                acronym.$categories.query(on: req.db).all()
            }
    }

Register this route handler at the bottom of boot(routes:)：

acronymsRoutes.get(":acronymID", "categories", use: getCategoriesHandler)

查询数据：
url：http://127.0.0.1:8080/api/acronyms/<acronymID>/categories
method：GET
成功后返回关联的 category
[{"id":"F9CDB53A-1560-4537-9BF4-670E8598CB11","name":"Teenager"}]

---

9.Category’s acronyms
Open Category.swift and add a new property annotated with @Siblings below
var name: String

    @Siblings(
        through: AcronymCategoryPivot.self,
        from: \.$category,
        to: \.$acronym
    )
    var acronyms: [Acronym]

Open CategoriesController.swift and add a new route handler after getHandler(_:)

    // http://127.0.0.1:8080/api/categories/<categoryID>/acronyms
    func getAcronymsHandler(_ req: Request) throws -> EventLoopFuture<[Acronym]> {
        Category.find(req.parameters.get("categoryID"), on: req.db)
            .unwrap(or: Abort(.notFound))
            .flatMap { category in
                category.$acronyms.get(on: req.db)
            }
    }

Register this route handler at the bottom of boot(routes:)

categoriesRoute.get(":categoryID", "acronyms", use: getAcronymsHandler)

查询数据：
url：http://127.0.0.1:8080/api/categories/<categoryID>/acronyms
method：GET
成功后返回关联的 acronym

[
    {
        "id":"F3320C03-8570-443F-A8AB-071681470DA4",
        "short":"MMD",
        "long":"么么哒",
        "user":{
            "id":"0DFD7B3A-F38D-43AA-8DD5-26B71E4FE3D0"
        }
    },
    {
        "id":"5FB16F6E-4BD1-48DB-8211-6F7611515913",
        "short":"TGD",
        "long":"明天是个好日子！",
        "user":{
            "id":"0DFD7B3A-F38D-43AA-8DD5-26B71E4FE3D0"
        }
    }
]

---

10.Removing the relationship
Open AcronymsController.swift and add the following below getCategoriesHandler(req:)

    // http://127.0.0.1:8080/api/acronyms/<acronymID>/categories/<categoryID>
    func removeCategoriesHandler(_ req: Request) throws -> EventLoopFuture<HTTPStatus> {
        let acronymQuery = Acronym.find(req.parameters.get("acronymID"), on: req.db)
            .unwrap(or: Abort(.notFound))
        let categoryQuery = Category.find(req.parameters.get("categoryID"), on: req.db)
            .unwrap(or: Abort(.notFound))
        return acronymQuery.and(categoryQuery)
            .flatMap { acronym, category in
                acronym.$categories
                    .detach(category, on: req.db)
                    .transform(to: .noContent)
        }
    }

register the route at the bottom of boot(routes:)

acronymsRoutes.delete(":acronymID", "categories", ":categoryID", use: removeCategoriesHandler)

删除关联
url：http://127.0.0.1:8080/api/acronyms/<acronymID>/categories/<categoryID>
method：DELETE
parameter：无
成功后返回的状态码是：HTTP/1.1 204 No Content

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