To get the current state of a database into a migration for Yii 2

yii2-reverse-migration.php

<?php

namespace app\commands;

use yii;

class MigrationReverserController extends \yii\console\Controller
{
    public function actionRun($schema = null)
    {
        if (null == $schema) {
            echo "Please provide a schema as the only argument.\n";
            return 1;
        }
    
        $schema = Yii::$app->db->schema;
        $tables = $schema->getTableNames();
        $addForeignKeys = '';
        $dropForeignKeys = '';
        $result = "public function up()\n{\n";
    
        foreach ($tables as $table) {
            $compositePrimaryKeyCols = array();
        
            // Create table
            $result .= '    $this->createTable(\'' . $table . '\', array(' . "\n";
            foreach ($schema->getTableSchema($table)->columns as $col) {
                $result .= '        \'' . $col->name . '\'=>\'' . $this->getColType($col) . '\',' . "\n";
                if ($col->isPrimaryKey && !$col->autoIncrement) {
                    // Add column to composite primary key array
                    $compositePrimaryKeyCols[] = $col->name;
                }
            }
            $result .= '    ), \'\');' . "\n\n";
        
            // Add foreign key(s) and create indexes
            foreach ($schema->getTableSchema($table)->foreignKeys as $fkName => $relation) {

                // Foreign key naming convention: fk_table_foreignTable_col (max 64 characters)
                $fkName = substr($fkName, 0 , 64);
                $refTable = $relation[0];
                $refTableColumn = array_keys($relation)[1];
                $col = $relation[$refTableColumn];
                $addForeignKeys .= '    $this->addForeignKey(' . "'$fkName', '$table', '$col', '$refTable', '$refTableColumn', 'NO ACTION', 'NO ACTION');\n\n";
                $dropForeignKeys .= '    $this->dropForeignKey(' . "'$fkName', '$table');\n\n";
            
                // Index naming convention: idx_col
                $result .= '    $this->createIndex(\'idx_' . $col . "', '$table', '$col', FALSE);\n\n";
            }
        
            // Add composite primary key for join tables
            if ($compositePrimaryKeyCols) {
                $result .= '    $this->addPrimaryKey(\'pk_' . $table . "', '$table', '" . implode(',', $compositePrimaryKeyCols) . "');\n\n";
            }
        }
    
        // After all the tables have been created ...
        $result .= $addForeignKeys;
        $result .= "}\n\n\n";
    
        // down function 
        $result .= "public function down()\n{\n";
        $result .= $dropForeignKeys; // This needs to come before the tables are dropped.
        foreach ($tables as $table) {
            $result .= '    $this->dropTable(\'' . $table . '\');' . "\n";
        }
        $result .= "}\n";
        echo $result;
    }

    public function getColType($col) {
        if ($col->isPrimaryKey && $col->autoIncrement) {
            return "pk";
        }
        $result = $col->dbType;
        if (!$col->allowNull) {
            $result .= ' NOT NULL';
        }
        if ($col->defaultValue != null) {
            $result .= " DEFAULT '{$col->defaultValue}'";
        } elseif ($col->allowNull) {
            $result .= ' DEFAULT NULL';
        }
        return $result;
    }
}