Question

我想创建一个html元素列表（包括查询结果），这些元素默认隐藏但用户可以切换该状态。我在下面尝试了几种不同的方式作为玩具示例，但无法工作。

此代码正确创建了三个按钮，这些按钮正确地改变了exps状态，但是它们并没有隐藏内容。

(:require  [reagent.core :as r] )
(def exps (r/atom [true true true]))
(defn like-component []
  [:div   
   (for [ [i r] (map-indexed vector  ["A" "B" "C"])] 
     [:div
       [:button {:on-click #(swap! exps update-in [i] not)}]
       (when (nth @exps i)
          [:pre (str i r)])])])

(r/render [like-component]
      (js/document.getElementById "app"))

另一方面，下面的代码只会创建一个元素，但它可以正常工作。

(defn expandable-view [e bool]
  (let [expanded (r/atom bool)]
          (fn []
            [:li
            [:div.expandable
              [:div.header {:on-click #(swap! expanded not)}
               "Click me to expand and collapse"]
              (if @expanded
                [:div.body  (allow-html :pre e)])]])))


(defn like-component []
  [:ul
    (vec
      (for [ e  ["A" "B" "C"]]
        (expandable-view e true ))) ])

(r/render [like-component]
          (js/document.getElementById "app"))

修改：可能相关： https://github.com/reagent-project/reagent/wiki/Beware-Event-Handlers-Returning-False

Answer 1

for是懒惰的，因此reagent无法告诉您在第一个代码段中解除引用exps。

我们可以通过显式解除引用原子来解决它。

(defn like-component []
  (apply str @exps) ;; because @exps is a vector, and reagent
                    ;; treat vectors as hiccup component
                    ;; we can't just put `@exps` here.
  [:div   
   (for [ [i r] (map-indexed vector  ["A" "B" "C"])] 
     [:div
       [:button {:on-click #(swap! exps update-in [i] not)}]
       (when (nth @exps i)
          [:pre (str i r)])])])

或者只是将惰性序列包裹在doall。

中

(defn like-component []
  [:div   
   (doall (for [ [i r] (map-indexed vector  ["A" "B" "C"])] 
     [:div
       [:button {:on-click #(swap! exps update-in [i] not)}]
       (when (nth @exps i)
          [:pre (str i r)])]))])

仅供参考，related discussions。

任何想法为什么我发布的第二个块只创建一个元素？

载体是Reagent的特殊公民，它们被视为打嗝/反应组件。

对于一个工作示例

(defn like-component []
  [:ul
    (doall
      (for [ e ["A" "B" "C"]]
        [expandable-view e true]))])

另请注意，我们正在使用[expandable-view e true]来正确构建试剂组件。有关更多信息，我强烈建议您阅读Using [] instead of ()和Creating Reagent Components。

Answer 2

我通过使用bootstrap实现了这种行为。我有一个状态原子中的记录列表，它们都是哈希映射。我为每个map添加一个：visible键，用于在记录上设置相应的bootstrap类。有一个功能可以切换有地图中的：可见设置。该组件使用按钮呈现记录，该按钮通过更改地图中的：visible值来切换可见性，从而导致组件重新呈现。

(defn toggle-visibility [k h]
  (let [new-v (if (= "show" (:visible h))
            "hidden"
            "show")]
    (state/set-value-in! [(state/this-page) :host-list k :visible] new-v)))

(defn host-component [k]
  (let [host (state/value-in [(state/this-page) :host-list k])]
    ^{:key k} [:div.panel.panel-default
               [:div {:class "panel-heading show"}
                [:div {:class (condp = (:status host)
                                "Active" "text-success"
                                "Inactive" "text-info"
                                "Unknown" "text-warning"
                                :else "text-danger")}
                 [:button {:type "button" :class "btn btn-default"
                           :aria-label "Expand"
                           :on-click #(toggle-visibility k host)}
                  [:span {:class (str "glyphicon "
                                      (if (= "show" (:visible host))
                                        "glyphicon-minus"
                                        "glyphicon-plus"))}]]
                 [:strong " IPv4 Address: "] (:ipv4 host)
                 [:strong " Hostname: "] (:hostname host)
                 [:div.pull-right (str "Host ID: " (:host-id host))]]]
               [:div {:class (str "panel-body " (:visible host))}
                [:ul.list-group
                 [:li.list-group-item
                  [:strong "Host Status: "] (:status host)]
                 [:li.list-group-item
                  [:strong "MAC Address: "] (:mac host)]
                 [:li.list-group-item
                  [:strong "IPv6 Address: "] (:ipv6 host)]
                 [:li.list-group-item
                  [:strong "Operating System: "] (:os host)]
                 [:li.list-group-item
                  [:strong "DHCP Client: "] (:dhcp host)
                  [:strong " DNS Entry: "] (:dns host)
                  [:strong " Revers DNS Entry: "] (:reverse-dns host)]
                 [:li.list-group-item
                 [:strong "Host Type: "] (:host-type host)]
                 [:li.list-group-item
                  [:strong "Network Group: "]
                  (str (:network-group host) " / " (:subgroup-name host))]
                 [:li.list-group-item
                  [:strong "Managed By: "] (:management-group host)]
                 [:li.list-group-item
                  [:strong "Creation Date: "] (:created-dt host)]
                 [:li.list-group-item
                  [:strong "Last Modified Date: "] (:last-modified-dt host)]
                 [:li.list-group-item
                  [:strong "Last Seen Date: "] (:last-seen-dt host)]]]]))

基本上，让bootstrap处理内容的显示/隐藏，让代码只是切换可见/不可见状态。完整的代码在theophilusx/Arcis

的github页面上

Reagent中的交互式列表

2 个答案: