Error : Undefined Is Not An Object (evaluating 'db.transaction') In Reactnative

I am following all the instructions for populating value from existing database for iOS from this :link And Using Following Code: import SQLite from 'react-native-sqlite-storage';

Solution 1:

You can try like this

importSQLitefrom'react-native-sqlite-storage';
var database_name = "sqliteexample"; // Add your Database namevar database_version = "1.0"; // Add your Database Versionvar database_size = 200000; // Add your Database Sizevar database_displayname = "SQL Database"; // Add your Database Displaynamevar db; 

exportdefaultclassAppextendsComponent<Props> {
errorCB(err) {
  console.log("SQL Error: " + err);
};

successCB() {
  console.log("SQL executed fine");
};

openCB() {
  console.log("Database OPENED");
};

openDB() {

 db = SQLite.openDatabase(database_name, database_version, database_displayname, database_size, this.openCB, this.errorCB);

}

populateDB() {

  db = SQLite.openDatabase(database_name, database_version, database_displayname, database_size, this.openCB, this.errorCB);
  db.transaction((tx) => {
    tx.executeSql("SELECT * FROM Users", [], (tx, results) => {
        console.log("Query completed");

        // Get rows with Web SQL Database spec compliance.var len = results.rows.length;
        console.log('len' + len)
        for (let i = 0; i < len; i++) {
          let row = results.rows.item(i);
          console.log(`User: ${row}`);
        }
      });
  });
}

render() {
    return (
<Viewstyle={styles.container} ><ButtononPress={this.openDB}
         title="open Database"color="#841584"/><ButtononPress={this.populateDB}
         title="Get Data"color="#841584"/></View>
    );
  }
}

Solution 2:

so I think it could be just timing issue. The safest way to obtain a database object would be inside the success callback which will receive a valid db object if all goes well in openDatabase. so change your code to this and try it...

openCB(myDB) {
  console.log("Database OPENED");
  db = myDB;
};

openDB() {
  SQLite.openDatabase({name : "sqliteexample", createFromLocation : 1}, this.openCB, this.errorCB);

}