Building CRUD Applications In Clojure - Meetup

Building CRUD applications in Clojurehttps://github.com/danielytics/diy-crud/

What do we need? Request Handler Routing Database Access Templating

DIY CRUD Request Handler Routing Database Access TemplatingRingCompojure, bidi, pedestal, silk, .Yesql, korma, lots of others for noSQL databasesEnlive, enliven, selmer, hiccup, clostache, .Lots of options!

DIY CRUD Request Handler Routing Database Access TemplatingRingBidiYesqlErinite/template

DIY CRUD Request Handler Routing Database Access TemplatingWhy ring? Defacto standardRingBidiYesqlErinite/template

DIY CRUD Request Handler Routing Database Access TemplatingRingBidiYesqlErinite/templateWhy bidi? Routes are data Reversible (URL - route, route - URL) Clojure and Clojurescript

DIY CRUD Request Handler Routing Database Access TemplatingWhy Yesql? Works with JDBC Write SQL as SQLRingBidiYesqlErinite/template

DIY CRUD Request Handler Routing Database Access TemplatingRingBidiYesqlErinite/templateWhy Erinite/template? Because I wrote it ;-) USP: template manipulation through data Will go into more detail later in this talk

DIY CRUDsetup a project lein new crud-talk; cd crud-talk; vim project.clj:dependencies [[org.clojure/clojure “1.7.0”][ring “1.4.0-RC1”][bidi “1.20.0”][yesql "0.4.0“ :exclusions [instaparse]][instaparse “1.4.1”] ; For clj 1.7 support[org.xerial/sqlite-jdbc "3.7.2"][hiccup "1.0.5"][erinite/template “0.2.0”]]:plugins [[lein-ring "0.9.6"]]:ring {:handler crud-talk.core/handler}

DIY CRUDcreate handler vim src/crud-talk/core.clj(ns crud-talk.core(:require[bidi.ring :as bidi-ring][yesql.core :refer [defqueries]][erinite.template.core :as t][hiccup.core :refer [html]]));; Other code goes here.(def handler (bidi-ring/make-handler routes))

DIY CRUDcreate our routes(def routes["/" {"items"{{:request-method :get} read-items{:request-method :post} create-item}["item/" t-method{:request-method:get} read-item:put} update-item:post} delete-item:delete} delete-item}}])

DIY CRUDcreate our routes(def routes["/" {"items"{{:request-method :get} read-items{:request-method :post} create-item}So wecan testin browser without using od{:request-method{:request-method:get} read-item:put} update-item:post} delete-item:delete} delete-item}}])

DIY CRUDread a list of items-- name: get-all-items-- Read a summary list of all items in database.SELECT id, name, quantityFROM items

DIY CRUDcreate database queries(def db-spec {:classname "org.sqlite.JDBC":subprotocol "sqlite":subname "db.sqlite"})(defqueries “queries.sql”)

DIY CRUDcreate database queriesMake sure you have a database setup: sqlite db.sqlitesqlite create table items (id int, name text, description text, qunantityint);sqlite insert into items values (1, ‘Test item’, ‘A test item. The first one’,5);sqlite insert into items values (2, ‘Another item’, ‘A test item. Thesecond one’, 26);sqlite insert into items values (3, ‘Item’, ‘The third item’, 3);

DIY CRUDcreate template(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit"} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])

DIY CRUDtransform template(def item-list-transformations{[:.items][:clone-for :items][:.items :.id][:content :id][:.items :.name][:content :name][:.items :.quantity] [:content :quantity][:.items :form][:set-attr :action :url]})

DIY CRUDcompile template(def -list-transformation))

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDthe data({:id 1:name “Test item”:quantity 5}{:id 2:name “Another item”:quantity 26}{:id 3:name “Item”:quantity 3})

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDthe data({:id 1:name “Test item”:url “/item/1”:quantity 5}{:id 2:name “Another item”:url “/item/2”:quantity 26}{:id 3:name “Item”:url “/item/3”:quantity 3})

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDthe data{:items ({:id 1:name “Test item”:url “/item/1”:quantity 5}{:id 2:name “Another item”:url “/item/2”:quantity 26}{:id 3:name “Item”:url “/item/3”:quantity 3})

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDthe data[:div {}[:h1 {} "Item List"][:table {:class “items”}[:tr {}[:td {:class “id”} 1][:td {:class “name”} “Test Item”][:td {:class “quantity”} 5][:td {}[:form {:action “/item/1” :method “post”}[:button {:type "submit“} "delete"]]]]].

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDthe data div h1 Item List /h1 table class “items” tr td class “id” 1 /td td class “name” Test Item /td td class “quantity” 5 /td td form action “/item/1” method “post” button type "submit“ delete /button /form /td /tr .

DIY CRUDitem list handler(defn read-items [request](let [items (map#(assoc % :url (str "/item/" (:id %)))(get-all-items db-spec))]{:status 200:body (html (item-list {:items items}))}))

DIY CRUDtest run! lein ring serverNow open localhost:3001/items

DIY CRUDErinite/template crash course(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit“} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])

DIY CRUDErinite/template crash course(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit“} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])[:.items][:clone-for :items]

DIY CRUDErinite/template crash course(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit“} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])[:.items][:clone-for :items]

DIY CRUDErinite/template crash course{:items ({:id 1:name “Test item”(def item-list-template:url “/item/1”[:div:quantity 5}[:h1 "Item List"][:table.items{:id 2[:tr:name “Another item”[:td.id] [:td.name] [:td.quantity]:url “/item/2”[:td [:form {:method “post”} [:button {:type "submit"}"delete"]]]]]:quantity26}[:hr] [:div "New item"]{:id 3[:form#new {:action "/items“ :method "post"}:name “Item”[:input.name {:type "text"}]:url “/item/3”[:input.description {:type "text"}]:quantity 3})[:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])[:.items][:clone-for :items]

DIY CRUDErinite/template crash course(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit“} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])[:.items :.id][:content :id]

DIY CRUDErinite/template crash course{:id 1:name “Test item”:url “/item/1”:quantity 5}(def item-list-template[:div[:h1 "Item List"][:table.items[:tr[:td.id] [:td.name] [:td.quantity][:td [:form {:method “post”} [:button {:type "submit“} "delete"]]]]][:hr] [:div "New item"][:form#new {:action "/items“ :method "post"}[:input.name {:type "text"}][:input.description {:type "text"}][:input.quantity {:type "text"}][:button {:type "submit"} "add"]]])[:.items :.id][:content :id]

DIY CRUDdetour: erinite/template-stylesheetsDetour Time!Erinite/template comes with a companion library: erinite/template-stylesheets

DIY CRUDdetour: erinite/template-stylesheetsDetour Time!Erinite/template comes with a companion library: erinite/template-stylesheets{[:.items][:.items :.id][:.items :.name][:.items :.quantity][:.items :form][:clone-for :items][:content :id][:content :name][:content :quantity][:set-attr :action :url]}

DIY CRUDdetour: erinite/template-stylesheetsDetour Time!Erinite/template comes with a companion library: erinite/template-stylesheets{[:.items][:.items :.id][:.items :.name][:.items :.quantity][:.items :form][:clone-for :items][:content :id][:content :name][:content :quantity][:set-attr :action :url]}

DIY CRUDdetour: erinite/template-stylesheets.items {clone-for: items;}.items .id {content: id;}.items .name {content: name;}.items .quantity {content: quantity;}.items form {set-attr: action url;}

DIY CRUDdetour: erinite/template-stylesheets.items {clone-for: items;}.items .id {content: id;}Now {your designers can update your.items .namecontent:name;templatetransformation selectors!}.items .quantity {content: quantity;}.items form {set-attr: action url;}

DIY CRUDdeleting items-- name: delete-item!-- Delete a specific item from the database.DELETE FROM itemsWHERE id :id

DIY CRUDdeleting items(defn delete-item [request](let [item-id (get-in request[:route-params :item-id])](delete-item! db-spec item-id){:status 302:headers {"Location" "/items"}}))

DIY CRUDdeleting items(defn delete-item [request](let [item-id (get-in request[:route-params :item-id])](delete-item! db-spec item-id){:status 302:headers {"Location" "/items"}}))

DIY CRUDcreate our routes(def routes["/" {"items"{{:request-method :get} read-items{:request-method :post} create-item}["item/" t-method{:request-method:get} read-item:put} update-item:post} delete-item:delete} delete-item}}])

DIY CRUDdeleting items(defn delete-item [request](let [item-id (get-in request[:route-params :item-id])](delete-item! db-spec item-id){:status 302:headers {"Location" "/items"}}))

DIY CRUDdeleting items(defn delete-item [request](let [item-id (get-in request[:route-params :item-id])](delete-item! db-spec item-id){:status 302:headers {"Location" "/items"}}))

DIY CRUD.and so on for create and update.

Where to next?LiberatorDefine resources as conditions and actions in a state machine.Very flexibleMakes it easy to be RFC compliantBut is lower level than I’d like

Where to next?YadaJUXT’s new Liberator competitorSimpler and higher level than LiberatorBuilt-in swagger support

Where to next?Erinite/crudThere is no good out-of-the-box CRUD library than I know of. So I planon making one.https://github.com/Erinite/crud

Where to next?Erinite/crudDoesn’t exist yet, so I’m taking feature requests

Where to next?Erinite/crudThe plan so far: Support any database (by implementing a protocol) Data-driven handlers (you define your resources as data, library doesthe rest) Just a handler, so you can mount it at any route you want

Questions?

DIY CRUD create database queries Make sure you have a database setup: sqlite db.sqlite sqlite create table items (id int, name text, description text, qunantity