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<?php |
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/** |
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* Class DataBase: |
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* This class performs the basic CRUD operations which compose of |
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* various methods such as create, read, update, and delete. |
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* This class class query the database to achieve its function. |
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* |
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* @author: Raimi Ademola <[email protected]> |
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* @copyright: 2016 Andela |
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*/ |
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namespace Demo; |
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use PDO; |
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class DataBaseQuery |
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{ |
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protected $tableName; |
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protected $splitTableField; |
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protected $formatTableValues; |
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protected $dbConnection; |
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/** |
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* This is a constructor; a default method that will be called automatically during class |
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* instantiation. |
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*/ |
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public function __construct($dbConn = null) |
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{ |
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if (is_null($dbConn)) { |
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$this->dbConnection = new DataBaseConnection(); |
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} else { |
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$this->dbConnection = $dbConn; |
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} |
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} |
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/** |
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* This method create or insert new users to the table. |
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* |
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* @param $associativeArray |
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* @param $tableName |
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* |
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* @return array |
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*/ |
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public function create($associativeArrayToCreate, $tableName) |
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{ |
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$tableFields = []; |
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$tableValues = []; |
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foreach ($associativeArrayToCreate as $key => $val) { |
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$tableFields[] = $key; |
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$tableValues[] = $val; |
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} |
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$unexpectedArray = array_diff($tableFields, $this->getColumnNames($tableName)); |
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if (count($unexpectedArray) < 1) { |
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$sql = 'INSERT INTO '.$tableName; |
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$sql .= '('.$this->splitTableField($tableFields).') '; |
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$sql .= 'VALUES ('.$this->formatTableValues($tableValues).')'; |
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$bool = $this->dbConnection->exec($sql); |
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return $bool; |
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} |
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throw new FieldUndefinedException('Oops, '.$this->splitTableField($unexpectedArray).' is not defined as a field'); |
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} |
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/** |
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* This method read the data in the table name of the id being passed to it. |
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* |
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* @param $id |
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* @param $tableName |
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* |
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* @return array |
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*/ |
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public static function read($id, $tableName, $dbConn = null) |
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{ |
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if (is_null($dbConn)) { |
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$dbConn = new DataBaseConnection(); |
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} |
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$sql = $id ? 'SELECT * FROM '.$tableName.' WHERE id = '.$id : 'SELECT * FROM '.$tableName; |
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$statement = $dbConn->prepare($sql); |
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$statement->execute(); |
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$results = $statement->fetchAll(PDO::FETCH_ASSOC); |
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if (count($results) < 1) { |
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throw new IdNotFoundException('Oops, the id '.$id.' is not in the table, try another id'); |
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} |
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return $results; |
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} |
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/** |
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* This method delete the table name of the id being passed to it. |
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* |
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* @param $update Params |
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* @param $associativeArrayToUpdate |
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* @param $tableName |
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* |
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* @return bool |
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*/ |
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public function update($updateParams, $associativeArrayToUpdate, $tableName) |
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{ |
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$updateSql = "UPDATE `$tableName` SET "; |
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unset($associativeArrayToUpdate['id']); |
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foreach ($associativeArrayToUpdate as $key => $val) { |
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$tableFields[] = $key; |
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} |
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$unexpectedArray = array_diff($tableFields, $this->getColumnNames($tableName)); |
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if (count($unexpectedArray) < 1) { |
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$updateSql .= $this->updateArraySql($associativeArrayToUpdate); |
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foreach ($updateParams as $field => $value) { |
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$updateSql .= " WHERE $field = $value"; |
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} |
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$statement = $this->dbConnection->exec($updateSql); |
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return $statement; |
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} |
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throw new FieldUndefinedException('Oops, '.$this->splitTableField($unexpectedArray).' is not defined as a field'); |
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} |
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/** |
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* This method delete the table name of the id passed to it. |
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* |
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* @param $id |
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* @param $tableName |
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* |
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* @return bool |
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*/ |
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public static function delete($id, $tableName, $dbConn = null) |
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{ |
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if (is_null($dbConn)) { |
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$dbConn = new DataBaseConnection(); |
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} |
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$sql = 'SELECT * FROM '.$tableName.' WHERE id = '.$id; |
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$statement = $dbConn->prepare($sql); |
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$statement->execute(); |
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$results = $statement->fetchAll(PDO::FETCH_ASSOC); |
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if (count($results) < 1) { |
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throw new IdNotFoundException('Oops, the id '.$id.' is not in the database, try another id'); |
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} |
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$sql = 'DELETE FROM '.$tableName.' WHERE id = '.$id; |
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$statement = $dbConn->exec($sql); |
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return true; |
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} |
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/** |
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* This method returns a string form an array by making us of the implode function. |
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* |
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* @param $tableField |
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* |
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* @return string |
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*/ |
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public function splitTableField($tableField) |
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{ |
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$splitTableField = implode(', ', $tableField); |
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return $splitTableField; |
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} |
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/** |
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* This method returns a string formed fron an array, It format the array. |
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* |
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* @param $tableValues |
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* |
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* @return string |
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*/ |
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public function formatTableValues($tableValues) |
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{ |
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$formattedValues = []; |
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foreach ($tableValues as $key => $value) { |
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$formattedValues[] = "'".$value."'"; |
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} |
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$ValueSql = implode(',', $formattedValues); |
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return $ValueSql; |
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} |
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/** |
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* This method returns a string formed from an array. |
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* |
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* @param $array |
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* |
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* @return string |
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*/ |
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public function updateArraySql($array) |
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{ |
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$updatedValues = []; |
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foreach ($array as $key => $val) { |
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$updatedValues[] = "`$key` = '$val'"; |
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} |
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$valueSql = implode(',', $updatedValues); |
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return $valueSql; |
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} |
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/** |
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* This method returns column fields of a particular table. |
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* |
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* @param $table |
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* |
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* @return array |
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*/ |
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public function getColumnNames($table) |
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{ |
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$tableFields = []; |
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$sql = 'SHOW COLUMNS FROM '.$table; |
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$stmt = $this->dbConnection->prepare($sql); |
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$stmt->bindValue(':table', $table, PDO::PARAM_STR); |
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$stmt->execute(); |
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$results = $stmt->fetchAll(PDO::FETCH_ASSOC); |
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foreach ($results as $result) { |
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array_push($tableFields, $result['Field']); |
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} |
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return $tableFields; |
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} |
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} |
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Adding an explicit array definition is generally preferable to implicit array definition as it guarantees a stable state of the code.
Let’s take a look at an example:
As you can see in this example, the array
$myArray
is initialized the first time when the foreach loop is entered. You can also see that the value of thebar
key is only written conditionally; thus, its value might result from a previous iteration.This might or might not be intended. To make your intention clear, your code more readible and to avoid accidental bugs, we recommend to add an explicit initialization $myArray = array() either outside or inside the foreach loop.