File uploads in Laravel - Step-by-Step Execution

Concept Flow - File uploads

User selects file in form

↓

Form submits POST request

↓

Laravel receives request

↓

Validate file input

↓

Store file

↓

Save file path or info

↓

Return success response

This flow shows how a user selects a file, submits it, Laravel validates and stores it, then responds.

Execution Sample

Laravel

<?php
// Controller method
public function upload(Request $request) {
  $request->validate(['file' => 'required|file']);
  $path = $request->file('file')->store('uploads');
  return back()->with('message', 'File uploaded: ' . $path);
}

This code validates a file upload, stores it in 'uploads' folder, and returns a success message.

Execution Table

Step	Action	Input/Condition	Result	Next Step
1	User selects file	File chosen in form	File ready to upload	Submit form
2	Form submits POST	Request with file data	Request received by Laravel	Validate file
3	Validate file	Check 'file' is present and is a file	Validation passes	Store file
4	Store file	Save file to 'uploads' directory	File saved, path returned	Return response
5	Return response	Success message with file path	User sees confirmation	END

💡 Process ends after returning success response to user.

Variable Tracker

Variable	Start	After Step 3	After Step 4	Final
$request	Empty	Contains uploaded file data	Same	Same
$path	Undefined	Undefined	uploads/filename.ext	uploads/filename.ext

Key Moments - 3 Insights

Why do we validate the file before storing it?

Validation ensures the file exists and is a valid upload. See step 3 in execution_table where validation passes before storing.

What happens if validation fails?

Laravel automatically redirects back with errors, stopping the process before storing. This is implied by the 'Fail' branch in concept_flow.

Where is the uploaded file saved?

The file is saved in the 'uploads' directory inside storage/app by default, as shown in step 4 of execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, what is the value of $path after step 4?

A Empty string

B Undefined

C uploads/filename.ext

D File contents

💡 Hint

Check the 'Result' column in step 4 of execution_table.

At which step does Laravel check if the uploaded file is valid?

A Step 3

B Step 2

C Step 4

D Step 5

💡 Hint

Look at the 'Action' and 'Input/Condition' columns in execution_table.

If the user does not select a file, what happens according to the flow?

A File is stored anyway

B Validation fails and error is returned

C File path is saved as empty string

D Process skips validation

💡 Hint

Refer to the 'Fail' branch in concept_flow and validation step in execution_table.

Concept Snapshot

File uploads in Laravel:
- User selects file in form and submits POST request.
- Laravel validates file input with $request->validate(['file' => 'required|file']).
- Store file using $request->file('file')->store('uploads').
- Store returns file path for saving or response.
- Return success or error response to user.

Full Transcript

This visual trace shows how file uploads work in Laravel. First, the user picks a file and submits the form. Laravel receives the request and validates the file input to ensure it exists and is a valid file. If validation passes, Laravel stores the file in the 'uploads' directory and returns the file path. Finally, Laravel sends a success message back to the user. If validation fails, Laravel returns an error and stops the process. Variables like $request hold the file data, and $path stores the saved file location. This step-by-step flow helps beginners see how file uploads are handled safely and clearly in Laravel.