投稿時間:2021-05-15 15:12:33 RSSフィード2021-05-15 15:00 分まとめ(14件)

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IT	ITmedia 総合記事一覧	[ITmedia News] Google I/O 2021に期待すること　Android 12詳細の他、Fitbitの買収効果は？	https://www.itmedia.co.jp/news/articles/2105/15/news038.html	wearos	2021-05-15 14:47:00
js	JavaScriptタグが付けられた新着投稿 - Qiita	【jQueryメモ】モーダル	https://qiita.com/Coco_syu/items/0024057544637940296c		2021-05-15 14:58:38
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	refile (0.6.2)がなくてbundle install できない	https://teratail.com/questions/338429?rss=all	refileがなくてbundleinstallできないやりたいことsshログインした状態でnbspbundlenbspinstallnbspを行いたい現状AWSEC本番環境へのデプロイ手順をついつい忘れがちなのでメモ自分のポートフォリオをAWSのEC上にデプロイしています。	2021-05-15 14:42:50
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	pythonのソケット通信で大きなデータが受信できない	https://teratail.com/questions/338428?rss=all		2021-05-15 14:35:30
Program	[全てのタグ]の新着質問一覧｜teratail（テラテイル）	rails SQLite3::ConstraintException: NOT NULL constraint failed: の原因と解決について	https://teratail.com/questions/338427?rss=all	railsSQLiteConstraintExceptionNOTNULLconstraintfailedの原因と解決について前提・実現したいことrailsで宿泊予約サービスのシステムを作成しています。	2021-05-15 14:01:38
Docker	dockerタグが付けられた新着投稿 - Qiita	Dockerを導入後に、(Rspec)テストコードが完全に使い物にならなくなった件について②	https://qiita.com/tochisuke221/items/374359eb3cff1182ed6c	良かった点自分なりに仮説を持ってエラーと向き合えたことで、結果としてゴールの近い部分までは近づけていた週間かなり闇に潜っていたが諦めず、手段を選ばず、解決までもっていけた粘り強さエラーと友達になれたもうどんなエラーも怖くない悪かった点コードのつつ細かいところまで理解せず、こういうものなんだなと、勝手に理解し本来調べるべきところを無意識的に無視していたことあと一歩だったのに、人に頼ってしまったこと悪くはないが、自力でやりたかった、、、汗深追いしすぎた時間かけすぎ週間おわりに今回エラーをとるまでにご協力してくださった方、本当にありがとうございました。	2021-05-15 14:45:36
Git	Gitタグが付けられた新着投稿 - Qiita	Springbootのソースをgitで公開する際、application.propertiesを公開しない記述	https://qiita.com/NoOne/items/9e20a0e38ba7a26b34a3	properties	2021-05-15 14:49:09
Ruby	Railsタグが付けられた新着投稿 - Qiita	herokuへのデプロイが失敗する　Precompiling assets failed.	https://qiita.com/kawara3782/items/4b913caee8d04d2a1ef8	しかし、Precompilingassetsfailedと表示されてデプロイに失敗しました。	2021-05-15 14:16:58
海外TECH	DEV Community	Create a todo list in React	https://dev.to/achukka/create-a-todo-list-in-react-4mp4	Create a todo list in ReactIn this tutorial we will learn how to create a todo list in React using Typescript Before we create the application let s set up our development environment Download and install the latest stable version of NodeThough Node is not really required to use React it bundle react applications into a neat packages that can be used relatively easy by other clients See this stack over flow post for more detailsSection Create a react applicationOpen your terminal and runnpx create react app todolist ーtemplate typescriptYes you read it right npx is a tool for executing node binaries This stack overflow post describes the differences wellOnce you run the above command completes your project structure should look like thisNow you can run your project by doingnpm start You should see your application running on your default browser at port If you have some other application react would ask you to allow it to run on the next availability portCongratulations you have successfully created your first react application Apologies if you are already an expert on ReactPlease commit your code to GitHub or any other code hosting platform You can refer to this commit for code structure In this section we will build a component to display items in tabular formatFeel free to skip this section by jumping this gistSection Define an interface to represent an item in the todo listWe store the task we are interested in doing as string and it s priority as number export interface Item task string priority number Section Define a component to show the itemsThis component will receive the items it needs to display through props Let s call it ToDoListIn the render method we collect the items for props If there are no items received return a text Ex Empty List class ToDoList extends React Component lt items Item gt render const items this props if items length return lt div gt Empty List lt div gt React Component takes props as first argument and state as second variableSince the above component does not involve any user interaction we don t have to store any state Hence we can ignore the constructor If there are any items we present in tabular format First create a table with a header lt table getTableStyleProps gt lt thead gt lt tr key task prioirity gt lt th gt Task lt th gt lt th gt Priority lt th gt lt tr gt lt thead gt lt table gt The key property in the row element would be used by React to decide whether this row needs to be re rendered when there is a change in this component React docs has a pretty good explanation on keysConstruct the table body by iterating items using map and creating a row lt tbody gt items map i index gt lt tr key i task i priority style backgroundColor index dddddd white gt lt td gt i task lt td gt lt td gt i priority lt td gt lt tr gt lt tbody gt It would be better if we organize our items based on priority Hence we sort them in ascending orderconst sortItems items Item Item gt return items sort i i gt i priority i priority Stitching everything together we get our ToDoList Component ToDoList tsximport React from react export interface Item task string priority number const getTableStyleProps gt return style width fontFamily arial sans serif borderCollapse collapse textAlign left padding px border px solid dddddd class ToDoList extends React Component lt items Item gt render const items this props if items length return lt div gt Empty List lt div gt const sortedItems sortItems items return lt table getTableStyleProps gt lt thead gt lt tr key task prioirity gt lt th gt Task lt th gt lt th gt Priority lt th gt lt tr gt lt thead gt lt tbody gt sortedItems map i index gt lt tr key i task i priority style backgroundColor index dddddd white gt lt td gt i task lt td gt lt td gt i priority lt td gt lt tr gt lt tbody gt lt table gt const sortItems items Item Item gt return items sort i i gt i priority i priority export default ToDoList Section Add ToDoList to AppFeel free to skip this section by jumping this gistAt this point we are ready to use the ToDoList component we wrote in the previous subsection Import the component and build an initial list of itemsimport React from react import ToDoList Item from ToDoList const initialList task Pick up Milk priority task Buy Eggs priority task Buy Bread priority Extend the App component to accept props and items as state Pass items received through state to ToDoList component in render methodclass App extends React Component lt items Item gt constructor props any super props this state items initialList render const items this state return lt div className App gt lt br gt lt ToDoList items items gt lt div gt Stitching everything together should give us our App component App tsximport React from react import ToDoList Item from ToDoList const initialList task Pick up Milk priority task Buy Eggs priority task Buy Bread priority class App extends React Component lt items Item gt constructor props any super props this state items initialList render const items this state return lt div className App gt lt br gt lt ToDoList items items gt lt div gt export default App Running the application by npm start should show a table like belowPlease remember to commit your changes at this point Section Define a component to add a new itemFeel free to skip section by jumping to this gistThis component would contain two text boxes one for task and another for priority and a button to submit the item Let s call it AddItemI sincerely apologize for bad naming open for feedback on theseFor this component we would need to store the input entered by user in a state variableimport React from react import Item from ToDoList class AddItem extends React Component lt addItem any Item gt constructor props any super props this state task priority Render the input form in a tabular formatrender return lt table gt lt tbody gt lt tr key gt lt td gt Task lt td gt lt td gt lt input id task type text placeholder Enter task here onChange this setTask gt lt td gt lt td gt Priority lt td gt lt td gt lt input id prioity type text placeholder Enter priority here onChange this setPriority gt lt td gt lt td gt lt input id submit type submit onClick this addItem gt lt td gt lt tr gt lt tbody gt lt table gt As you might have already guessed we will use the functions setTask and setPriority to update the state of item setTask evt any this setState task evt target value setPriority evt any this setState priority parseInt evt target value Once we collected the inputs we should validate them const isValid item Item boolean gt return item task amp amp item priority Now we can submit the item using the function addItemaddItem evt any const item this state if isValid item this props addItem item this setState task priority The above snippet calls a function addItem on props This would pass state or data to the parent component In react world this strategy is called Lifting State Up We do this so that AddItem can be reused to create newer items For the above three functions to be available in render method we need to bind to this object in the constructor class AddItem extends React Component lt addItem any Item gt constructor props any super props this state task priority this setTask this setTask bind this this setPriority this setPriority bind this this addItem this addItem bind this Joining everyything together gives us the AddItem component AddItem tsximport React from react import Item from ToDoList const isValid item Item boolean gt return item task amp amp item priority class AddItem extends React Component lt addItem any Item gt constructor props any super props this state task priority this setTask this setTask bind this this setPriority this setPriority bind this this addItem this addItem bind this setTask evt any this setState task evt target value setPriority evt any this setState priority parseInt evt target value addItem evt any const item this state if isValid item this props addItem item this setState task priority render return lt table gt lt tbody gt lt tr key gt lt td gt Task lt td gt lt td gt lt input id task type text placeholder Enter task here onChange this setTask gt lt td gt lt td gt Priority lt td gt lt td gt lt input id prioity type text placeholder Enter priority here onChange this setPriority gt lt td gt lt td gt lt input id submit type submit onClick this addItem gt lt td gt lt tr gt lt tbody gt lt table gt export default AddItem Section Add AddItem to App componentFeel free to skip this section by jumping to this gistAddItem component can be now imported to AppBefore adding a new item we would need to check if it already exists Let s write a helper function isPartOf that looks if item is present in items const isPartOf item Item items Item boolean gt return items some it gt it priority item priority Implement addItem using the helper function isPartOf If item already exists alert the userElse update the stateaddItem item Item const items this state if isPartOf item items alert Item with priorirty item priority exists return this setState items items concat item We should concatenate the item to the current list since states are immutable in reactBind addItem in the App constructorclass App extends React Component lt items Item gt constructor props any super props this state items initialList this addItem this addItem bind this Combining all the code parts together should give us our new App component App tsximport React from react import AddItem from AddItem import ToDoList Item from ToDoList const initialList task Pick up Milk priority task Buy Eggs priority task Buy Bread priority const isPartOf item Item items Item boolean gt return items some it gt it priority item priority class App extends React Component lt items Item gt constructor props any super props this state items initialList this addItem this addItem bind this addItem item Item const items this state if isPartOf item items alert Item with priorirty item priority exists return this setState items items concat item render const items this state return lt div className App gt lt AddItem addItem this addItem gt lt br gt lt ToDoList items items gt lt div gt export default App Your todo list app is ready to used now Running npm start should bring a window like belowPlease check this commit for full code ️Congratulations you have successfully created a todo list in React I have also hosted this application on Code Sandbox Feel free to play with itThanks for reading through the entire article Please reach out with questions comments and or feedback	2021-05-15 05:46:55
海外TECH	DEV Community	React Tutorial – How to Work with Multiple Checkboxes (New Course Launched - Details Inside)	https://dev.to/myogeshchavan97/react-tutorial-how-to-work-with-multiple-checkboxes-11an	React Tutorial How to Work with Multiple Checkboxes New Course Launched Details Inside When working on React project sometimes we need to display multiple checkbox options for the user But handling multiple checkboxes in React is completely different from how we use the normal HTML checkboxes So In this article we ll see how to work with multiple checkboxes in React You will learn How to use checkbox as a Controlled Input in ReactHow to use array map and reduce method for complex calculationHow to create a specific length array pre filled with some specific valueThis article is a part of my Mastering Redux course Here s a preview of the app we ll be building in the course So let s get started How to Work with Single CheckboxLet s start with single checkbox functionality before moving to multiple checkboxes In this article I will be using React Hooks syntax for creating component so If you re not familiar with React Hooks check out my Introduction to React Hooks article Take a look at the below code lt div className App gt Select your pizza topping lt div className topping gt lt input type checkbox id topping name topping value Paneer gt Paneer lt div gt lt div gt Here s a Code Sandbox Demo In the above code we ve just declared a single checkbox which is similar to how we declare a HTML checkbox So we re able to easily check and uncheck the checkbox as shown below But to display on the screen whether it s checked or not we need to convert it to Controlled Input In React Controlled Input is the one that is managed by state so the input value can be changed only by changing the state related to that input Take a look at the below code export default function App const isChecked setIsChecked useState false const handleOnChange gt setIsChecked isChecked return lt div className App gt Select your pizza topping lt div className topping gt lt input type checkbox id topping name topping value Paneer checked isChecked onChange handleOnChange gt Paneer lt div gt lt div className result gt Above checkbox is isChecked checked un checked lt div gt lt div gt Here s a Code Sandbox Demo In the above code we ve declared isChecked state in the component with the initial value of false using the useState hook const isChecked setIsChecked useState false Then for the input checkbox we ve given two extra props checked and onChange like this lt input checked isChecked onChange handleOnChange gt Whenever we click on the checkbox the handleOnChange handler function will be called which is used to set the value of isChecked state const handleOnChange gt setIsChecked isChecked So If the checkbox is checked we re setting the isChecked value to false and If the checkbox is unchecked we re setting the value to true using isChecked and that value we re passing in the input checkbox for the prop checked This way the input checkbox becomes a controlled input whose value is managed by the state In React It s always recommended to use Controlled Input for input fields even If the code looks complicated because it guarantees that the input change happens inside only the onChange handler The state of the input will not be changed in any other way and you ll always get the correct and updated value of the state of the input Only in rare cases you can use the React ref to use the input in an uncontrolled way How to Handle Multiple CheckboxesNow let s look at the way to handle multiple checkboxes Take a look at this Code Sandbox Demo Here we re displaying a list of toppings and their corresponding price and based on which toppings are selected we need to display the total amount Previously with the single checkbox we were having only isChecked state and based on that we were changing the state of the checkbox But now we have a lot of checkboxes so it s not practical to add multiple useState calls for each checkbox So let s declare an array in the state indicating the state of each checkbox To create an array equal to the length of the number of checkboxes we can use the array fill method like this const checkedState setCheckedState useState new Array toppings length fill false Here we ve declared a state with an initial value as an array filled with the value false So If we ve toppings then the checkedState state array will contain false values like this false false false false false And once we check uncheck the checkbox we ll change the corresponding false to true and true to false Here s a final Code Sandbox Demo The complete App js code looks like this import useState from react import toppings from utils toppings import styles css const getFormattedPrice price gt price toFixed export default function App const checkedState setCheckedState useState new Array toppings length fill false const total setTotal useState const handleOnChange position gt const updatedCheckedState checkedState map item index gt index position item item setCheckedState updatedCheckedState const totalPrice updatedCheckedState reduce sum currentState index gt if currentState true return sum toppings index price return sum setTotal totalPrice return lt div className App gt lt h gt Select Toppings lt h gt lt ul className toppings list gt toppings map name price index gt return lt li key index gt lt div className toppings list item gt lt div className left section gt lt input type checkbox id custom checkbox index name name value name checked checkedState index onChange gt handleOnChange index gt lt label htmlFor custom checkbox index gt name lt label gt lt div gt lt div className right section gt getFormattedPrice price lt div gt lt div gt lt li gt lt li gt lt div className toppings list item gt lt div className left section gt Total lt div gt lt div className right section gt getFormattedPrice total lt div gt lt div gt lt li gt lt ul gt lt div gt Let s understand what we re doing here We ve declared the input checkbox as shown below lt input type checkbox id custom checkbox index name name value name checked checkedState index onChange gt handleOnChange index gt Here we ve added a checked attribute with the value of corresponding true or false from the checkedState state So each checkbox will have the correct value of their checked state We ve also added onChange handler and we re passing the index of the checkbox which is checked unchecked to the handleOnChange method The handleOnChange handler method looks like this const handleOnChange position gt const updatedCheckedState checkedState map item index gt index position item item setCheckedState updatedCheckedState const totalPrice updatedCheckedState reduce sum currentState index gt if currentState true return sum toppings index price return sum setTotal totalPrice Here we re first looping over the checkedState array using array map method and If the value of the passed position parameter matches with the current index then we re reversing its value so If the value is true then it will be converted to false using item and If the value is false then it will be converted to true If the index does not match with the provided position parameter then we re not reversing its value but we re just returning the value as it is const updatedCheckedState checkedState map item index gt index position item item the above code is the same as the below codeconst updatedCheckedState checkedState map item index gt if index position return item else return item I used the ternary operator because it makes the code shorter but you can use any one of them If you re not much familiar with how the array methods like map or reduce works then check out my this article Next we re setting the checkedState array to the updatedCheckedState array This is very important because If you don t update the checkedState state inside the handleOnChange handler then you will not be able to check uncheck the checkbox This is because we re using the checkedState value for the checkbox to determine if the checkbox is checked or not as it s a controlled input as shown below lt input type checkbox checked checkedState index onChange gt handleOnChange index gt Note that we ve created a separate updatedCheckedState variable and we re passing that variable to the setCheckedState function and we re using the reduce method on updatedCheckedState and not on the original checkedState array This is because by default the setCheckedState function used to update the state is asynchronous Just because you called the setCheckedState function does not guarantee that you will get the updated value of the checkedState array in the next line So we ve created a separate variable and used that in the reduce method Check out my this article if you re not familiar with how the state works in React Then to calculate the total price we re using the array reduce method const totalPrice updatedCheckedState reduce sum currentState index gt if currentState true return sum toppings index price return sum The array reduce method receives parameters out of which we re using only which are sum currentState and index You can use different names if you want as they re just parameters We re also passing as the initial value also known as the accumulator value for the sum parameter Then inside the reduce function we re checking If the current value of the checkedState array is true or not If it s true that means the checkbox is checked so we re adding the value of corresponding price using sum toppings index price If the checkedState array value is false then we re not adding its price but just returning the calculated previous value of sum Then we re setting that totalPrice value to the total state using setTotal totalPrice This way we re correctly able to calculate the total price for selected toppings as can be seen below Here s a Preview link of the above Code Sandbox demo to try it yourself Thanks for reading Most developers struggle with understanding how Redux works But every React developer should be aware of how to work with Redux as industry projects mostly use Redux for managing larger projects So to make it easy for you I have launched a Mastering Redux course In this course you will learn Redux from the absolute beginning and you ll also build a complete food ordering app from scratch using Redux Click the below image to join the course and get the limited time discount offer and also get my popular Mastering Modern JavaScript book for free Want to stay up to date with regular content regarding JavaScript React Node js Follow me on LinkedIn	2021-05-15 05:34:35
海外TECH	DEV Community	My experience at Layer5	https://dev.to/alphax86/my-experience-at-layer5-fa5	My experience at Layer Joining LayerIt was Dec I was looking at some programs at LFX Programs previously CommunityBridge where some orgs like Linux Kernel CNCF post openings on mentorships to work on At that time I came across a mentorship program called Meshery I applied out of interest and found a link to join their slack I joined in and realized that the program needs community member for that program such that he she has done impactful contributions previously in the project Then I quickly withdrawn the application and started becoming active in the community That s how I joined Layer My initial worksAt the beginning I wanted to test the project as a user but felt a bit hard because I wasn t ready for cloud native at that moment Tweaked some settings in my system but no results So I thought is there any way to contribute the project and that s how I started looking on Documentation I gradually looked at some issues commented and took up the work The project s documentation is mainly made of Jekyll so I had to install Ruby and since Makefile is dominant in order to install dependencies I used Linux as my main development environment It felt a bit hard at first because I never used Jekyll before Then gradually I learned about Jekyll and YAML fixed some bugs and done even bigger works My greatest work so farThe greatest work so far I ve done is to redesign mesheryctl command reference page The page was outdated for a while so I was given a task to redesign and update the doc It felt tedious at first then some ideas came in took my peer s help and finally completed The doc was so impressive such that it s updated with the latest spec and understandable My surprise After taking a lot works I got recognized such that I ve been added to their community and their GitHub organization It all happened at one day a team was created including me and I got a message that your works have been recognized a lot So we decided to add you on our community profile in our website I WAS SURPRISED AND EXCITED AT THE SAME TIME O O It really got a pride feeling within me So I accepted Link First profile At presentAfter doing some doc work I realized why not try new field and work on it That s where I again used the project but this time with Minikube cluster enabled If you guys wonder what is Minikube it s a simple one node local Kubernetes cluster which can be run on Virtualization enabled machines like WSL HyperV VMware etc It WORKED I was in state of awe I can t believe I really ran a cloud native project locally Then I started installing Golang learning about Kubernetes and Golang and started working on mesheryctl as tester and now a contributor will catch up soon coz I started recently xD ConclusionIn a nutshell I thought only skills matter in such a DEV ecosystem But I was wrong If it s open source community also matters in order to co operate and work in harmony I learned that when I joined Layer It s an interesting experience and I hope this continues long further	2021-05-15 05:17:09
ニュース	@日本経済新聞 電子版	英社ワクチン、ゼロリスク社会に「10万分の1」の壁 https://t.co/PuKJkAaN8o	https://twitter.com/nikkei/statuses/1393435199615102981	社会	2021-05-15 05:16:55
ニュース	BBC News - Home	Guardiola influence & teenager's deal with parents - meet Chelsea's Women's Champions League final opponents	https://www.bbc.co.uk/sport/football/57118689	Guardiola influence amp teenager x s deal with parents meet Chelsea x s Women x s Champions League final opponentsEverything you need to know about Chelsea s Women s Champions League final opponents including Pep Guardiola the analyst turned hero and a teenager s deal with her parents	2021-05-15 05:15:39
ビジネス	東洋経済オンライン	｢生理痛がつらい人｣が食べていいもの､悪いもの 食事でとる｢油｣のバランスを意識してみる | 健康 | 東洋経済オンライン	https://toyokeizai.net/articles/-/427085?utm_source=rss&utm_medium=http&utm_campaign=link_back	東洋経済オンライン	2021-05-15 14:30:00