Laravel Eager Loading - Load only specific columns
Stefan Bogdanescu
Founder & Senior Architect · 2026-06-29
# Laravel Eager Loading: How to Load Only Specific Columns from Relationships
As developers working with Eloquent and large datasets, performance optimization is paramount. One of the most common tasks we face is eager loading relationships—loading related models efficiently in a single query. However, a frequent requirement arises: we don't need every column from the related model; we only need a subset.
This post addresses a specific challenge: how to eager load a model while restricting the data returned from the related relationship to only specific columns. We will diagnose why the initial approach fails and provide the correct, performant solution.
## The Pitfall of Direct Collection Manipulation
The scenario you described involves attempting to apply column selection methods directly onto an Eloquent Collection that has already been loaded via eager loading.
Your attempt looked like this:
```php
public function car()
{
return $this->hasOne('Car', 'id')->get(['emailid','name']); // This causes the error
}
```
And you encountered the error: `Call to undefined method Illuminate\Database\Eloquent\Collection::getAndResetWheres()`.
This error occurs because you are trying to use methods intended for building database queries (like `where` or `select`) on an Eloquent Collection. Collections represent the *result set* of a query; they do not possess methods to modify the underlying SQL query that generated them. The magic of eager loading happens when you define the relationship and fetch the data simultaneously from the database.
## The Correct Approach: Constraining the Relationship Query
To load only specific columns, the selection must be applied at the point where the database query is being constructed—that is, directly on the relationship definition or the initial query builder call, not after the model has been hydrated into a collection.
There are two primary, effective ways to achieve this column restriction in Laravel:
### Method 1: Constraining Columns via the Relationship (The Eloquent Way)
If you need specific columns from the related model whenever that relationship is loaded, you define the selection within the relationship itself using the `with()` method combined with the `select()` constraint. This ensures that the subsequent eager loading query only fetches those necessary fields.
In your case, if you are loading models that have a `Car` relationship:
```php
// In your main model (e.g., User)
public function cars()
{
// Tell Eloquent to load the 'cars' relationship,
// but only select the 'emailid' and 'name' columns from the Car table.
return $this->hasOne('Car', 'id')->select(['emailid', 'name']);
}
// When fetching data:
$user = User::with('cars')->find(1);
// Accessing the relationship will now only return the selected columns.
```
### Method 2: Constraining Columns Directly on Eager Loading (The Performance Way)
If you are eager loading a single relationship, you can apply the `select()` constraint directly within the `with()` method when fetching the data. This is often cleaner for specific, one-off loads and ensures the database query is optimized immediately.
```php
$user = User::with(['cars' => function ($query) {
// Constrain the eager loaded relationship query to only select necessary columns
$query->select('emailid', 'name');
}])->find(1);
```
This method delegates the column selection back to the underlying database query, which is significantly more efficient than loading all data and then trying to filter it in PHP memory. This adherence to query optimization principles is central to building fast applications with Laravel, as emphasized by best practices on the [Laravel Company website](https://laravelcompany.com).
## Conclusion: Prioritizing Database Efficiency
The error you encountered highlights a crucial distinction in Eloquent: **modifying an Eloquent Collection vs. modifying a Query Builder.** Never attempt to use query-building syntax on a loaded collection. Instead, always push your constraints down to the database layer using `select()` when defining eager loads or relationships. By adopting these methods, you ensure that your application remains fast, efficient, and scalable, leveraging Laravel's power for optimized data retrieval.