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Reader Library

Overview

The Reader library is a PHP class designed to facilitate the reading and processing of CSV files with headers at the top row. It provides various features for handling CSV data, including validation, error handling, and customizable processing through callback functions.

Motivation

I created the Reader library to simplify and standardize the process of reading and validating CSV files in my PHP projects. After encountering repetitive issues with inconsistent CSV formats and error handling, I wanted a reusable solution that could be easily customized and extended for different use cases.

Namespace

Installation

To use the Reader library, include the file in your project and ensure that you have the necessary dependencies installed. You can install it via Composer:

Usage

Creating an Instance

To use the Reader library, include the following use statement at the top of your PHP file:

You can create an instance of the Reader class by passing optional parameters to the constructor.

Parameters

• $params: An associative array of optional parameters to initialize the Reader. Common parameters include:
  • delimiter: Character used to separate values in the CSV file (default: ,).
  • enclosure: Character used to enclose values in the CSV file (default: ").
  • escape: Character used to escape special characters (default: \).
  • has_header: Indicates if the CSV file has a header row (default: true).
  • columns: Array of required column names for validation.
  • error_threshold: If the error count exceeds this threshold, the CSV reader stops reading the data (default: 1000).

Reading a CSV File

To read a CSV file, use the read method. You can also provide a callback function to process each row.

Callback Function

To perform custom validation or processing on each row of your CSV, you can define a callback function. This callback should accept two parameters:

• $row: An associative array representing the current row's data.
• $index: The row index (starting from 1).

The callback can return one of the following:

• true — The row is valid and should be processed (no changes).
• An associative array with:
  • 'status' => false and 'column_errors' => [...] — The row is invalid, and the provided error messages will be reported.
  • 'status' => true and 'row' => $modifiedRow — The row is valid, and you want to modify the row before further processing (e.g., change values, normalize data).
  • 'status' => false and 'skip' => true — The row should be skipped entirely and not included in the processed results.

Important: You must set the callback before calling Reader::read(). Use the following method to register your callback:

Using the Callback for custom validations

• Here, $method refers to the name of the function that will be invoked on the $context object for each row during CSV processing.

Note: Custom validations via callback are optional. If you do not set a callback, only the built-in column validations (as defined in your columns array) will be applied.

Column Validations

Each column definition in the columns parameter supports the following options:

• name (required): The key name for the value in the resulting associative array.
• column_name (required): The header name as it appears in the CSV file.
• type (optional): The expected data type. Supported types: string, integer, float, boolean, date.
• validate (optional): Pipe-separated validation rules that determine how the data in the column should be checked for correctness. Supported rules include:
  • required: Ensures that the value must be present.
  • lowercase: Converts the value to lowercase.
  • uppercase: Converts the value to uppercase.
  • strip_tags: Removes any HTML and PHP tags from the value.
  • unique: Ensures that the value is unique across the dataset.
  • min_length: Sets the minimum number of characters required for the value.
  • max_length: Sets the maximum number of characters allowed for the value.
  • htmlentities: Converts special characters to HTML entities.
  • strip_quotes: Removes quotes from the value.
  • urlencode: Encodes the value for use in a URL. (More validations will be added soon.)
• allowed_values (optional): An array of allowed values for the column. If set, the value in the CSV must match one of the values in this array. Example: 'allowed_values' => ['active', 'inactive'].

Example uage with column definitions:

Example

Progress Callback Feature (Added in v1.2)

The Reader class now supports a progress callback feature, allowing you to receive updates on the progress of CSV file processing. This is especially useful for large files, as you can provide feedback to users (e.g., update a progress bar or log progress).

How It Works

• You can set a progress callback function using the setProgressCallback() method.
• The callback will be called periodically (every 100 rows by default) and once at the end of processing.
• The callback receives two parameters:
  • $rowsProcessed (int): The number of rows processed so far.
  • $totalRows (int|null): The total number of rows, if available (may be null if not pre-counted).

Example Usage

Notes

• To show CSV import progress on your website, have your progress callback save the current progress (like rows processed) somewhere your frontend can read it—such as a JSON file, cache, or database. Then, use AJAX or WebSockets on the frontend to fetch and display this progress (for example, in a progress bar). This lets users see live updates during large imports.
• The progress callback is optional. If not set, no progress updates will be sent.
• The callback is called every 100 rows by default. You can change this interval using the setter setProgressCallbackInterval() if needed.
• The final call to the callback is made after all rows are processed.

See also:

• setProgressCallback() method in Reader.php
• Example usage in tests/ReaderUsage.php

Exception Handling Example (Added in v1.5.5)

The Reader library allows for custom validation and exception handling during the reading process. To ensure robust error handling, all custom validations must be wrapped inside a try-catch block. Below is an example demonstrating how to implement exception handling in your CSV processing.

Explanation

In this example, the CsvProcessor class initializes the Reader with column definitions and sets a callback that simulates an exception being thrown. The process method attempts to read a CSV file and handles any exceptions that occur, providing feedback on the error. This allows for better debugging and user feedback during CSV processing.

Testing

To run the tests, use the following command:

This will run all test files

To run a specific test file just use the following command:

Error Handling

The library tracks errors encountered during the reading process. If errors occur, they are stored in an array, and an error file can be generated for review.

Methods

initialize(array $params)

Initializes the Reader with given parameters.

setDelimiter(string $delimiter)

Sets the delimiter for CSV.

setEnclosure(string $enclosure)

Sets the enclosure character for CSV.

setEscape(string $escape)

Sets the escape character for CSV.

setHasHeader(bool $has_header)

Sets whether the CSV has a header row.

setColumns(array $columns)

Sets the required columns for validation.

setDirectoryPath(string $directory_path)

Sets the directory path for error files.

setFileName(string $file_name)

Sets the name of the error file.

setErrorCountThreshold(int $error_threshold)

Sets the error count threshold.

storeErrorRows(array $error_rows, array $header)

Stores rows with errors into a CSV file.

Conclusion

The Reader library provides a robust solution for reading and processing CSV files in PHP. With its validation features and customizable processing, it is suitable for various applications that require CSV data handling.

License

This library is licensed under the MIT License.