<form method="POST">
    <h3>Editing: DatabaseRule.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

namespace Illuminate\Validation\Rules;

use Closure;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Support\Str;

trait DatabaseRule
{
    /**
     * The table to run the query against.
     *
     * @var string
     */
    protected $table;

    /**
     * The column to check on.
     *
     * @var string
     */
    protected $column;

    /**
     * The extra where clauses for the query.
     *
     * @var array
     */
    protected $wheres = [];

    /**
     * The array of custom query callbacks.
     *
     * @var array
     */
    protected $using = [];

    /**
     * Create a new rule instance.
     *
     * @param  string  $table
     * @param  string  $column
     * @return void
     */
    public function __construct($table, $column = 'NULL')
    {
        $this-&gt;column = $column;

        $this-&gt;table = $this-&gt;resolveTableName($table);
    }

    /**
     * Resolves the name of the table from the given string.
     *
     * @param  string  $table
     * @return string
     */
    public function resolveTableName($table)
    {
        if (! Str::contains($table, '\\') || ! class_exists($table)) {
            return $table;
        }

        if (is_subclass_of($table, Model::class)) {
            $model = new $table;

            if (Str::contains($model-&gt;getTable(), '.')) {
                return $table;
            }

            return implode('.', array_map(function (string $part) {
                return trim($part, '.');
            }, array_filter([$model-&gt;getConnectionName(), $model-&gt;getTable()])));
        }

        return $table;
    }

    /**
     * Set a &quot;where&quot; constraint on the query.
     *
     * @param  \Closure|string  $column
     * @param  array|string|int|null  $value
     * @return $this
     */
    public function where($column, $value = null)
    {
        if (is_array($value)) {
            return $this-&gt;whereIn($column, $value);
        }

        if ($column instanceof Closure) {
            return $this-&gt;using($column);
        }

        if (is_null($value)) {
            return $this-&gt;whereNull($column);
        }

        $this-&gt;wheres[] = compact('column', 'value');

        return $this;
    }

    /**
     * Set a &quot;where not&quot; constraint on the query.
     *
     * @param  string  $column
     * @param  array|string  $value
     * @return $this
     */
    public function whereNot($column, $value)
    {
        if (is_array($value)) {
            return $this-&gt;whereNotIn($column, $value);
        }

        return $this-&gt;where($column, '!'.$value);
    }

    /**
     * Set a &quot;where null&quot; constraint on the query.
     *
     * @param  string  $column
     * @return $this
     */
    public function whereNull($column)
    {
        return $this-&gt;where($column, 'NULL');
    }

    /**
     * Set a &quot;where not null&quot; constraint on the query.
     *
     * @param  string  $column
     * @return $this
     */
    public function whereNotNull($column)
    {
        return $this-&gt;where($column, 'NOT_NULL');
    }

    /**
     * Set a &quot;where in&quot; constraint on the query.
     *
     * @param  string  $column
     * @param  array  $values
     * @return $this
     */
    public function whereIn($column, array $values)
    {
        return $this-&gt;where(function ($query) use ($column, $values) {
            $query-&gt;whereIn($column, $values);
        });
    }

    /**
     * Set a &quot;where not in&quot; constraint on the query.
     *
     * @param  string  $column
     * @param  array  $values
     * @return $this
     */
    public function whereNotIn($column, array $values)
    {
        return $this-&gt;where(function ($query) use ($column, $values) {
            $query-&gt;whereNotIn($column, $values);
        });
    }

    /**
     * Register a custom query callback.
     *
     * @param  \Closure  $callback
     * @return $this
     */
    public function using(Closure $callback)
    {
        $this-&gt;using[] = $callback;

        return $this;
    }

    /**
     * Get the custom query callbacks for the rule.
     *
     * @return array
     */
    public function queryCallbacks()
    {
        return $this-&gt;using;
    }

    /**
     * Format the where clauses.
     *
     * @return string
     */
    protected function formatWheres()
    {
        return collect($this-&gt;wheres)-&gt;map(function ($where) {
            return $where['column'].','.'&quot;'.str_replace('&quot;', '&quot;&quot;', $where['value']).'&quot;';
        })-&gt;implode(',');
    }
}
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