Learners Store

Steps to Build Offline APK for Real Device – React Native

To test our React Native App in our phone, we can follow the following steps.

STEP 1 : Generate JS Bundle

npx react-native bundle \
--platform android \
--dev false \
--entry-file index.js \
--bundle-output android/app/src/main/assets/index.android.bundle \
--assets-dest android/app/src/main/res

Run the above command in your project root folder. This will pack your code into a static file.

STEP 2: Build the APK

navigate to android folder using this command in terminal.

cd android

Now build a debug APK using gradle

./gradlew assembleDebug

Now you can find the APK file in the following path

android/app/build/outputs/apk/debug/app-debug.apk

Now we can install this APK in our Android phone to test our App.

TypeError: cli.init is not a function – React Native

This error will come while running the following command.

  npm install -g react-native-cli

This happens because react-native-cli is deprecated and not compatible with recent versions of node js. Especially from Node 18 + it throws this error.

To fix this issue first Uninstall react-native-cli using the following command.

npm uninstall -g react-native-cli

use the official CLI as follows

npx @react-native-community/cli init MyApp

Now it will install all the required packages to run the App.

How to avoid prefixing every table with schema name while creating new tables ?

Lets assume schema name is my_data. If we want to avoid prefixing every table with my_data while creating a new table, we can set it in the search_path.

 SET search_path TO my_data;

Now we can create a new table like this.

CREATE TABLE courses (
    id SERIAL PRIMARY KEY,
    course_name TEXT
);

By using the above code, courses table will be created in my_data by default.

What command we need to use to list all tables inside the specific schema ?

Suppose if the schema name is my_data, then we need to use the following command to list all the tables inside the my_data schema.

\dt my_data.*

Now, if you want to create a new table inside the my_data schema, we just need to prefix the table name with the schema name like this.

CREATE TABLE my_data.students (
    id SERIAL PRIMARY KEY,
    name TEXT NOT NULL,
    age INT,
    enrolled_on DATE DEFAULT CURRENT_DATE
);

This will create the students table inside the my_data schema.

What command we need to use to list all schemas in the current PostgreSQL Database ?

\dn

This command is used to list All Schemas in the current PostgreSQL Database along with their owners.

Example Output:

   List of schemas

    Name     |    Owner
-------------+-------------
 public      | test_user
 mydata      | postgres

The \dn command is a PostgreSQL-specific meta-command used inside the psql command-line interface.

The default schema is usually public. Generally we use /dn to check existing schemas.