laravel/framework · error · RuntimeException

This database driver requires a type, see the virtualAs / st

Error message

This database driver requires a type, see the virtualAs / storedAs modifiers.

What it means

MySQL's typeComputed() throws because MySQL has no standalone 'computed' SQL column type. Computed/virtual columns in MySQL are defined by attaching a virtualAs() or storedAs() expression to a real underlying type (e.g. INTEGER, VARCHAR). Throwing here signals that the developer asked for a computed column without specifying its base type.

Source

Thrown at src/Illuminate/Database/Schema/Grammars/MySqlGrammar.php:1186

     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeGeography(Fluent $column)
    {
        return $this->typeGeometry($column);
    }

    /**
     * Create the column definition for a generated, computed column type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return void
     *
     * @throws \RuntimeException
     */
    protected function typeComputed(Fluent $column)
    {
        throw new RuntimeException('This database driver requires a type, see the virtualAs / storedAs modifiers.');
    }

    /**
     * Create the column definition for a vector type.
     *
     * @param  \Illuminate\Support\Fluent  $column
     * @return string
     */
    protected function typeVector(Fluent $column)
    {
        return isset($column->dimensions) && $column->dimensions !== ''
            ? "vector({$column->dimensions})"
            : 'vector';
    }

    /**
     * Get the SQL for a generated virtual column modifier.
     *

View on GitHub (pinned to bd6b5437e6)

Solutions

Replace $table->computed($expr) with a concrete base type plus the modifier: $table->string('col')->virtualAs($expr) (not persisted) or ->storedAs($expr) (persisted).
If you only need a virtual expression, ensure the base type matches the expression's result type so MySQL can store/represent it.
Switch the table to a driver that supports the computed type natively (sqlsrv) if you cannot rewrite the column.

Example fix

// before
$table->computed('full_name');

// after (MySQL)
$table->string('full_name')
      ->virtualAs('concat(first_name, " ", last_name)');
// or persisted:
$table->string('full_name')
      ->storedAs('concat(first_name, " ", last_name)');

Defensive patterns

Strategy: validation

Validate before calling

// Use a base type + modifier instead of the 'computed' pseudo-type
// (validation is by construction: never call $table->computed() on MySQL)

Prevention

On MySQL/MariaDB always pair a concrete type with virtualAs()/storedAs().
Reserve $table->computed() for SQL Server.
Lint migrations for bare computed() usage before deploying.

When it happens

Trigger: Calling $table->computed('full_name') directly on a MySQL/MariaDB connection. The correct shape is $table->string('full_name')->virtualAs('concat(first_name, last_name)') or ->storedAs(...). Using the bare 'computed' pseudo-type only works on SQL Server / Postgres.

Common situations: Porting a SQL Server migration (where 'computed' is valid) to MySQL; misunderstanding the API after reading cross-driver docs; auto-generated migrations from a tool that emits a generic computed type.

Related errors

AI-assisted analysis of laravel/framework@bd6b5437e6 (2026-08-06). Data as JSON: /data/errors/8f64d859efcfc9d4.json. Report an issue: GitHub.