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Reformat to one of the docs

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Mike Thompson 2017-07-30 20:12:56 +10:00
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docs/Loading-Initial-Data.md
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@ -1,35 +1,19 @@
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
## Table Of Contents
- [Bootstrapping Application State](#bootstrapping-application-state)
- [1. Register Handlers](#1-register-handlers)
- [2. Kick Start Reagent](#2-kick-start-reagent)
- [3. Loading Initial Data](#3-loading-initial-data)
- [Getting Data Into `app-db`](#getting-data-into-app-db)
- [The Pattern](#the-pattern)
- [Scales Up](#scales-up)
- [Cheating - Synchronous Dispatch](#cheating---synchronous-dispatch)
- [Loading Initial Data From Services](#loading-initial-data-from-services)
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
## Bootstrapping Application State
To bootstrap a re-frame application, you need to:
1. register handlers
1. register handlers:
- subscription (via `reg-sub`)
- events (via `reg-event-db` or `reg-event-fx`)
- effects (via `reg-fx`)
- coeffects (via `reg-cofx`)
2. kickstart reagent (views)
3. Load the right initial data into `app-db` which might be a `merge` of:
2. kickstart reagent (views)
3. Load the right initial data into `app-db` which might, for example, be a `merge` of:
- Some default values
- Values stored in LocalStorage
- Values obtained via service calls to server
- etc, etc
Point 3 is the interesting bit and will be the main focus of this page, but let's work our way through them ...
Point 3 is the interesting bit and will be the main focus of this page,
but let's work our way through them ...
## 1. Register Handlers
@ -43,7 +27,8 @@ and register your handlers in the one step, like this "event handler" example:
```
As a result, there's nothing further you need to do because
handler registration happens as a direct result of loading the code (presumably via a `<script>` tag in your HTML file).
handler registration happens as a direct result of loading the code
(presumably via a `<script>` tag in your HTML file).
## 2. Kick Start Reagent
@ -70,7 +55,7 @@ we want it to source and render some data held in `app-db`.
First, we'll create the subscription handler:
```Clojure
(re-frame/reg-sub ;; a new subscription handler
(re-frame.core/reg-sub ;; a new subscription handler
:name ;; usage (subscribe [:name])
(fn [db _]
(:display-name db))) ;; extracts `:display-name` from app-db
@ -80,7 +65,7 @@ And now we use that subscription:
```clj
(defn main-panel
[]
(let [name (re-frame/subscribe [:name])] ;; <--- a subscription <---
(let [name (re-frame.core/subscribe [:name])] ;; <--- a subscription <---
[:div "Hello " @name]))) ;; <--- use the result of the subscription
```
@ -101,7 +86,7 @@ values must be put in `app-db` via an event handler.
Here's an event handler for that purpose:
```Clojure
(re-frame/reg-event-db
(re-frame.core/reg-event-db
:initialise-db ;; usage: (dispatch [:initialise-db])
(fn [_ _] ;; Ignore both params (db and event)
{:display-name "DDATWD" ;; return a new value for app-db
@ -115,7 +100,7 @@ We'll need to dispatch an `:initialise-db` event to get it to execute. `main` se
```Clojure
(defn ^:export main
[]
(re-frame/dispatch [:initialise-db]) ;; <--- this is new
(re-frame.core/dispatch [:initialise-db]) ;; <--- this is new
(reagent/render [main-panel]
(js/document.getElementById "app")))
```
@ -139,36 +124,36 @@ quick sketch of the entire pattern. It is very straight-forward.
## The Pattern
```Clojure
(re-frame/reg-sub ;; the means by which main-panel gets data
:name ;; usage (subscribe [:name])
(re-frame.core/reg-sub ;; supplied main-panel with data
:name ;; usage (subscribe [:name])
(fn [db _]
(:display-name db)))
(re-frame/reg-sub ;; we can check if there is data
(re-frame.core/reg-sub ;; we can check if there is data
:initialised? ;; usage (subscribe [:initialised?])
(fn [db _]
(not (empty? db)))) ;; do we have data
(re-frame/reg-event-db
(re-frame.core/reg-event-db
:initialise-db
(fn [db _]
(assoc db :display-name "Jane Doe")))
(defn main-panel ;; the top level of our app
[]
(let [name (re-frame/subscribe [:name])] ;; we need there to be good data
(let [name (re-frame.core/subscribe [:name])] ;; we need there to be good data
[:div "Hello " @name])))
(defn top-panel ;; this is new
[]
(let [ready? (re-frame/subscribe [:initialised?])]
(let [ready? (re-frame.core/subscribe [:initialised?])]
(if-not @ready? ;; do we have good data?
[:div "Initialising ..."] ;; tell them we are working on it
[main-panel]))) ;; all good, render this component
(defn ^:export main ;; call this to bootstrap your app
[]
(re-frame/dispatch [:initialise-db])
(re-frame.core/dispatch [:initialise-db])
(reagent/render [top-panel]
(js/document.getElementById "app")))
```
@ -184,17 +169,17 @@ Your `main` might look like this:
```Clojure
(defn ^:export main ;; call this to bootstrap your app
[]
(re-frame/dispatch [:initialise-db]) ;; basics
(re-frame/dispatch [:load-from-service-1]) ;; ask for data from service-1
(re-frame/dispatch [:load-from-service-2]) ;; ask for data from service-2
(reagent/render [top-panel]
(re-frame.core/dispatch [:initialise-db]) ;; basics
(re-frame.core/dispatch [:load-from-service-1]) ;; ask for data from service-1
(re-frame.core/dispatch [:load-from-service-2]) ;; ask for data from service-2
(reagent.core/render [top-panel]
(js/document.getElementById "app")))
```
Your `:initialised?` test then becomes more like this sketch:
```Clojure
(reg-sub
(re-frame.core/reg-sub
:initialised? ;; usage (subscribe [:initialised?])
(fn [db _]
(and (not (empty? db))
@ -237,3 +222,7 @@ Up: [Index](README.md)&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
Next: [Talking To Servers](Talking-To-Servers.md)
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
<!-- END doctoc generated TOC please keep comment here to allow auto update -->