I was trying to create a new project to follow a course, but creating the project with npx create-react-app my_appcreated everything with React 18 version and its corresponding scripts for that version.
How can I choose the version of React I want to install?
When I went to create a new project with the command npx create-react-app nombre-app, I got the following:
I did as it appears in the log and globally uninstalled create-react-app but I still get that warning when I try to create a project. According to the create-react-app documentation to update it, it updates the package every time a new project is created, but this didn't happen.
npm version: 8.6.1
node version: v16.13.1
I'm trying to compile an image with Docker on Windows 10 (I think, I still don't know much about it) with the command docker build -t getting-started .and the following log appears with the error:
[+] Building 8.2s (12/15)
=> [internal] load build definition from Dockerfile 0.0s
=> => transferring dockerfile: 32B 0.0s
=> [internal] load .dockerignore 0.0s
=> => transferring context: 2B 0.0s
=> resolve image config for docker.io/docker/dockerfile:1 2.0s
=> [auth] docker/dockerfile:pull token for registry-1.docker.io 0.0s
=> CACHED docker-image://docker.io/docker/dockerfile:1@sha256:42399d4635eddd7a9b8a24be879d2f9a930d0ed040a61324cfdf59 0.0s
=> [internal] load .dockerignore 0.0s
=> [internal] load build definition from Dockerfile 0.0s
=> [internal] load metadata for docker.io/library/node:12-alpine 1.1s
=> [auth] library/node:pull token for registry-1.docker.io 0.0s
=> [internal] load build context 0.0s
=> => transferring context: 2.49kB 0.0s
=> CACHED [1/5] FROM docker.io/library/node:12-alpine@sha256:1ecf7789a48e604a841409e65cf2e172d5a014ecd5e60689137d785 0.0s
=> ERROR [2/5] RUN apk add --no-cache python g++ make 4.6s
------
> [2/5] RUN apk add --no-cache python g++ make:
#11 0.368 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/main/x86_64/APKINDEX.tar.gz
#11 1.910 fetch https://dl-cdn.alpinelinux.org/alpine/v3.14/community/x86_64/APKINDEX.tar.gz
#11 4.561 ERROR: unable to select packages:
#11 4.603 python (no such package):
#11 4.603 required by: world[python]
------
executor failed running [/bin/sh -c apk add --no-cache python g++ make]: exit code: 1
This is the content of my Dockerfile:
# syntax=docker/dockerfile:1
FROM node:12-alpine
RUN apk add --no-cache python g++ make
WORKDIR /app
COPY . .
RUN yarn install --production
CMD ["node", "src/index.js"]
I am following Docker's Sample application guide : https://docs.docker.com/get-started/02_our_app/
Devs, I have a timer that freezes when it runs beforeunloadwhen trying to change direction or refresh the page. When the prompt is canceled the timer continues. But that's not the behavior I expect.
I hope that even if the stopwatch prompt appears, it beforeunloadcontinues to count...
The timer works with useEffect and useRef, normal.
And here is my usage of beforeunload:
useEffect(() => {
const handleBeforeUnload = (event) => event.preventDefault();
if (checkTestState(TEST_STATES.IN_PROCESS)) {
window.addEventListener('beforeunload', handleBeforeUnload);
} else {
window.removeEventListener('beforeunload', handleBeforeUnload);
}
return () => window.removeEventListener('beforeunload', handleBeforeUnload);
});
I have two arrangements:
const myArray1 = [{updatedProp: 'prop'}, {updatedProp2: 'prop2'}];
const myArray2 = [{oldProp: 'oldProp'}, 'Una cadena', {oldProp2: 'oldProp2'}];
How do I make it so that under the condition that if the element is a Object, it must be replaced by the new one in the order the arrays are initially found?
The result I expect is:
[updatedProp, 'A string', updatedProp2]
That is, something like:
const myUpdateArray = myArray2.map(element => {
if(typeof element === 'object'){
return //elemento actualizado
}
});
I have the following request with axios :
axios.post(`${baseURL}/test/updateInProcess/`, {
params:{
id: _id
}
});
But when my API with Express and Mongoose receives the request, it always sends undefined in that id, here I receive it:
exports.updateInProcess = (req, res, next) => {
const { id } = req.query;
console.log('id: ' + id);
}
Departure:
id: undefined
When I make the request with the parameters in Postman if the req.query. When I do it with axios the request is carried out but it doesn't do what it should because it sends undefined.
how can I create a loading circle, for example, when I make an XmlHtpp request with Axios in my view with ReactJS?
<Get/>Currently I achieve that with the dependency tag react-axios.
Note : react-axios is not axios. React Axios has COMPONENTS with Get, Put, etc. tags. More information: react-axios - npm
With the component <Get/>I achieve something that I really like and that is that I can put a Progress Loading , look at the following:
render() {
return (
<div>
<Get url="/api/user" params={{id: "12345"}}>
{(error, response, isLoading, makeRequest, axios) => {
if(error) {
return (<div>Something bad happened: {error.message} <button onClick={() => makeRequest({ params: { reload: true } })}>Retry</button></div>)
}
else if(isLoading) {
return (<div>Loading...</div>)
}
else if(response !== null) {
return (<div>{response.data.message} <button onClick={() => makeRequest({ params: { refresh: true } })}>Refresh</button></div>)
}
return (<div>Default message before request is made.</div>)
}}
</Get>
</div>
)
}
In the condition if(isLoading)I can perfectly fit an animation component, for example the <CircularProgress/>MaterialUI one . This works great... But the logic I need doesn't allow me to use the tag for requests with react-axios <Get/>.
For that reason, I would like to know how or where to put a "Loading" during a request with Axios... For example, if I had this:
async function getUser() {
try {
const response = await axios.get('/user?ID=12345');
console.log(response);
} catch (error) {
console.error(error);
}
}
Where do I put my <div>Loading...</div>while waiting for the response or where do I manipulate a boolean variable to trigger it on render? That the variable remains false while I wait for the response and changes to true when it receives a response and there I stop the view that it is loading...
I have an array of arrays (with boolean elements), say,
const array = [[false, false], [false, true], [true, true]];
And I want to use a reduce()to count how many true there are, this is what I try:
const check = (array) => {
const numNotAnsweredQuestion = array.reduce((acc, elem1) => {
return (
acc +
elem1.reduce((acc2, elem2) => {
return elem2 ? acc2 + 1 : acc2;
}, 0)
);
}, 0);
return numNotAnsweredQuestion;
};
That is, I accumulate twice, or not?
The browser returns the function:
I need my Schema to receive an array with this structure:
const arrayAnswers: [
{description: 'String', isCorrect: true},
{description: 'String', isCorrect: false},
{description: 'String', isCorrect: false}
]
This is the schematic I write:
const mongoose = require('mongoose');
const {Schema} = mongoose;
const fields = {
answers: [Object]
}
const question = new Schema(Object.assign(fields), {timestamps: true});
module.exports = {
Model: mongoose.model('question', question),
fields
};
Can the schema for that field be like this or is there something wrong with it [Object]?
I have read about Schema.Types.Mixedand about subdocuments, but I wouldn't know how to make the subdocument. And according to the Mixed makes it lose the ability to autodetect and save changes, so I don't know what repercussions it can have exactly with what I do.
I have two arrangements:
const opciones = ['A', 'B', 'C', 'D'];
const valoracion = [true, false, false, false];
And I want to create an array containing objects with this structure, based on the data from the previous arrays:
const respuestas = [
{opc: 'A', val: true},
{opc: 'B', val: false},
{opc: 'C', val: false},
{opc: 'D', val: false},
]
How can I do it in Javascript?
I have the following code created in Konsolede CentOS7where, as you can see, I try to create a process with the function/command fork()and manage the different circumstances of using it:
#include <stdio.h>
#include <unistd.h>
void main(){
pid_t pid;
pid = fork();
if(pid == -1){
printf("Error al crear el proceso hijo\n");
exit(0);
}
if(pid){
printf("Proceso padre, el PID de mi hijo es %d\n", pid);
}else{
printf("Soy el hijo, ejecutando herramienta date\n");
execve("bin/date", NULL, NULL);
}
}
When executing gcc test_fork.cin Konsolede Linux CentOSI get the following error:
[vapaternina@localhost ~]$ gcc test_fork.c
test_fork.c: En la función ‘main’:
test_fork.c:10:3: aviso: declaración implícita incompatible de la función interna ‘exit’ [activado por defecto]
exit(0);
^
I have the following code to make an array in LaTex:
\begin{eqnarray*}
\Hess f(\bar{x}) & = &
\left( \begin{array}{ccc}
\partial f_{11} & \partial f_{12} & \partial f_{13} \\
\partial f_{21} & \partial f_{22} & \partial f_{23} \\
\partial f_{31} & \partial f_{32} & \partial f_{33}
\end{array} \right)\\ & = &
\left( \begin{array}{cccc}
0 & 1 & 0\\
1 & 0 & 1\\
0 & 1 & 0
\end{array} \right)
\end{eqnarray*}
Which shows this:
However, that is not what I want and it is not what it should show, according to the reference that I used (and that I also tried) the code should generate what it showed above but with the arrays aligned by the equals symbol '=' as I indicated with the '&'.
I also tried \begin{align*} which should give the same result (with simple equations, that is, without matrices, I get the alignment).
So, I don't know if what I'm doing is wrong or not allowed, in any case I need help to do that if it can be done.
I have the following code in Overleaf:
\begin{align}
\frac{\partial\Lagr}{\partial x_{1}} &= x_{2} + 2x_{1}\lambda_{1} = 0 \\ \frac{\partial\Lagr}{\partial x_{2}} &= x_{1} + x_{3} + 2x_{2}\lambda_{1} + \lambda_{2} = 0\\
%
\frac{\partial\Lagr}{\partial x_{3}} &= x_{2} + \lambda_{2} = 0\\
%
\frac{\partial\Lagr}{\partial \lambda_{1}} &= x_{1}^2 + x_{2}^2 - 2 = 0 \\ \frac{\partial\Lagr}{\partial \lambda_{2}} &= x_{2} + x_{3} -2 = 0
\end{align}
Which generates this:
Which is what I want, however, later I do another one \begin{align}in which I want the numbers of the equations to be reset, to start from 1 again, this has the following code:
\begin{align}
-2\cdot\alpha_{1} &= 0\\
2\cdot\alpha_{1} + \alpha_{2} &= 0\\
\alpha_{2} &= 0\\
\Rightarrow \alpha_{1} = \alpha_{2} &= 0
\end{align}
And this continues with the sequence of numbers:
Which is not what I want.
There I found commands like:
And they don't work for me, or I don't know how to use them in these sections.
I have a card_video.xml(which is the element my is populated from RecyclerView) which should look like this according to Android Studio's design view, I understand that it doesn't always look that way due to the properties of each device, but it should look like this for each element:
Which has the following code:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardCornerRadius="15dp"
app:cardUseCompatPadding="true">
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:weightSum="1">
<TextView
android:layout_weight=".1"
android:paddingLeft="10dp"
android:id="@+id/textViewIndex"
android:textSize="20sp"
android:layout_gravity="center_vertical"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:text="1"/>
<TextView
android:layout_weight=".8"
android:id="@+id/textViewNameCourse"
android:textAlignment="center"
android:layout_gravity="center_vertical"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textSize="16sp"
android:text="Introduction"/>
<ImageButton
android:id="@+id/imageButtonSee"
style="@style/Widget.AppCompat.Button.Borderless.Colored"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_weight=".1"
android:src="@drawable/ic_eye_black_24dp" />
</LinearLayout>
</android.support.v7.widget.CardView>
When filling the Recycler with data, it ends up looking like this:
Here the code of the Adapter
public class VideoAdapter extends RecyclerView.Adapter<VideoAdapter.ViewHolder>{
ArrayList<Video> nVideoList;
private int layout;
private static OnItemClickListener listener;
public VideoAdapter(ArrayList<Video> nVideoList, int layout, OnItemClickListener listener) {
this.nVideoList = nVideoList;
this.layout = layout;
this.listener = listener;
}
@Override
public VideoAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View v = LayoutInflater.from(parent.getContext()).inflate(layout, parent, false);
return new VideoAdapter.ViewHolder(v);
}
@Override
public void onBindViewHolder(VideoAdapter.ViewHolder holder, int position) {
holder.index.setText((position+1)+"");
holder.name.setText(nVideoList.get(position).getName());
//events
}
@Override
public int getItemCount() {
return nVideoList.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{
TextView name;
TextView index;
ImageView imageView;
public ViewHolder(View itemView) {
super(itemView);
name = itemView.findViewById(R.id.textViewNameCourse);
index = itemView.findViewById(R.id.textViewIndex);
imageView = itemView.findViewById(R.id.imageButtonSee);
imageView.setOnClickListener(this);
}
@Override
public void onClick(View view) {
// Llamas el método onItemClickListener() de la interfaz OnItemClickListener
listener.onItemClickListener(view, getLayoutPosition());
}
}
public interface OnItemClickListener{
// Este método recibe como parámetro la vista del elemento seleccionado
void onItemClickListener(View view, int position);
}
}
Here is the XML where the RecyclerView is:
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.vycto.atomiccourses.VideoActivity">
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:orientation="horizontal"
android:weightSum="1"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<ImageButton
android:id="@+id/buttonBackToCourses"
style="@style/Widget.AppCompat.Button.Colored"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight=".33"
android:src="@drawable/ic_arrow_back_white_24dp" />
<ImageButton
android:id="@+id/buttonHome"
style="@style/Widget.AppCompat.Button.Colored"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight=".33"
android:src="@drawable/ic_home_white" />
<ImageButton
style="@style/Widget.AppCompat.Button.Colored"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight=".33"
android:src="@drawable/ic_list_white" />
</LinearLayout>
<LinearLayout
android:id="@+id/linearLayout2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="12dp"
android:orientation="vertical"
android:padding="10dp"
app:layout_constraintHorizontal_bias="0.0"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/linearLayout">
<android.support.v7.widget.CardView
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardCornerRadius="15dp">
<ImageView
android:id="@+id/imageViewCoverVideos"
android:layout_width="match_parent"
android:layout_height="127dp"
android:scaleType="fitStart"
android:src="@drawable/cover_default" />
</android.support.v7.widget.CardView>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/textViewNameCourse"
android:text="Android"
android:layout_marginTop="3dp"
android:textAlignment="center"
android:textSize="22sp"/>
<TextView
android:id="@+id/textViewDescriptionCourse"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="10dp"
android:text="Ingrese aqui descripcion"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/textViewCost1"
android:layout_gravity="end"
android:textStyle="bold"
android:text="Cost: $0 (1 MONTH)"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerViewVideos"
android:layout_width="match_parent"
android:layout_height="200dp"></android.support.v7.widget.RecyclerView>
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/buttonBuy"
android:text="Buy"
android:layout_marginTop="5dp"
android:layout_marginBottom="3dp"
style="@style/Widget.AppCompat.Button.Colored"/>
</LinearLayout>
</android.support.constraint.ConstraintLayout>
I need all the ones you create to be displayed as the first image, thanks.
Hello, download PyQt5 from its official website and in some videos I see that it brings an "executable" file called designer. When downloading it it doesn't bring that file, just a folder called so I don't know what to do with it, so how can I use PyQt?
The following image has everything that the directory contains after unzipping it, I use PyCharm as IDE.
Can someone please help me?
Hello, I would not know how to generate BigInteger of constant nlength . KI found this algorithm here:
BigInteger r;
Random rnd = new Random(System.currentTimeMillis());
do {
r = new BigInteger(n.bitLength(), rnd);
} while (r.compareTo(n) >= 0);
This successfully generates random numbers in a range, but it's not what I'm looking for, what I'm looking for is for example:
Input
n = 3
k = 5
Output
12345
54321
67854
Hello, I have tried to take the root of a BigIntegerwith the method pow, BigIntegerbecause I cannot find the method that performs the square root operation on the instances of this class.
BigInteger sqr = n.pow(0.5);
However the method powonly BigIntegerreceives integers. If there is a way or if the method to take the square root of a BigIntegerdoes exist, I would appreciate it if you could clarify it for me, thanks.
I'm using Python 3.6 and trying to read a multi-line input to store it in a variable and then manage each line in a list for example. The structure of the code is something simple like this:
print("Escriba la lista de ciudades de la siguiente forma:")
print("Ciudad origen | Ciudad destino | Ruta | Distancia")
cad.append(input())
I want to enter 3 lines for example (without pressing ENTER, copying and pasting for example)
Line 1
Line 2
Line 3
And I want python to store the 3 lines in a variable
I don't know if there will be a good practice for this, since I have a screen with a JMenu with many items
->Menu
->Usuario
{
->Iniciar sesion
->Registrarse
->Informacion de usuario
}
->Ayuda
{
-> Instrucciones de juego
-> Acerca del juego
}
So I create a JFrame Form for each of these if needed, registration window, login window, information window, help window, etc. And I don't know if this is a common practice or if there is a more practical way to work this.
I got this error all of a sudden, I mark the R class in red in the Java code.
AAPT err(Facade for 557143976): libpng error: Not a PNG file
Error:Execution failed for task ':app:mergeDebugResources'.
Some file crunching failed, see logs for details
I already used Rebuild Project and Clean Project several times...