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Constraint Builders

The package provides two (2) convenient ways to query the Reader and the ResultSet instances. They can be used to perform manipulation independently of the instance giving you more controls over which records you want to access from your input document.

Statement

The first mechanism is the League\Csv\Statement class which is a constraint builder that more or less mimic the behaviour of query builders in the database world. It can filter, order and limit the records to be shown. It does so by adding and combining constraints. Once the constraint is built, it will process your input and always return a ResultSet instance. Of note, the resulting constraint can be applied on multiple documents as the instance is immutable and completely independent of the input.

Retrieving all the rows

Starting with version 9.6.0, the class exposes the Statement::create named constructor to ease object creation.

To start using the Statement class you should use the create method. It returns a valid instance ready to already process your document or on which you can add more constraints. Because the Statement object is immutable, each time its constraint methods are called they will return a new Statement object without modifying the current Statement object. Once your constraint is ready to be used, use its process method on a TabularDataReader class.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()->process($reader);
// $records is a League\Csv\ResultSet instance

The process method returns a new TabularDataReader on which each constraint have been applied. If no constraint has been added the return object will contain the same data as its input.

Where clauses

To filter the records from your input you may use the where method. The method can be called multiple time and each time it will add another constraint filter. This option follows the First In First Out rule. The filter excepts a callable with the following signature:

function(array $record, string|int $key): bool;

The $key argument is optional and is only used if you want to filter the row over its offset.

If you omit the $key argument, the callable is similar to the one used by array_filter. For example the following filter will remove all the records whose 3rd field does not contain a valid email:

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->where(fn (array $record): bool => false !== filter_var($record[2] ?? '', FILTER_VALIDATE_EMAIL))
    ->process($reader);
// $records is a League\Csv\ResultSet instance

New since version 9.16.0

To ease the Statement::where usage the following methods are introduced: andWhere, whereNot, orWhere and xorWhere;

These methods are used to filter the record based on their columns value. Instead of using a callable, the methods require three (3) arguments. The first argument is the column to filter on. It can be as a string (the column name, if it exists) or an integer (the column offset, negative indexes are supported). The second argument is a valid comparison operator in a case-insensitive way. The third argument is the value you want to compare the column value with.

As an example the Statement instance below will select the records whose 2nd cell value is the integer 10 or where the birthdate column contains a date string representation that match the submitted regular expression.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->andWhere(1, '=', '10') //filtering is done of the second column
    ->orWhere('birthdate', 'regexp', '/\d{1,2}\/\d{1,2}\/\d{2,4}/') //filtering is done on the `birthdate` column
    ->whereNot('firstname', 'starts_with', 'P') //filtering is done case-sensitively on the first character of the column value
    ->process($reader);
// $records is a League\Csv\ResultSet instance

The methods support the basic comparison operators using their strict version in PHP:

The following parameter can only be used if the submitted value is an array as PHP’s in_array function is used for comparison. If the value to compare is a scalar value or null, in_array is used on strict mode otherwise the comparison is relaxed.

use League\Csv\Statement;

$constraints = Statement::create()->orWhere('direction', 'not in', ['east', 'north']);

The following parameter can only be used if the submitted value is a tuple represented as a PHP’s array as a list where the first argument represents the range minimal value and the second argument, the range maximal value.

use League\Csv\Statement;

$constraints = Statement::create()->andWhere('points', 'between', [3, 5]);

The following parameters can only be used if the submitted value and the column value are string.

Internally they use one of the following PHP’s function str_contains, str_starts_with, str_ends_wtih or preg_match.

For complex constraints you can, instead of specifying an simple operator, choose to specificy a callback. In that case the callback method will be evaluated with the value of the specified column.

use League\Csv\Reader;
use League\Csv\Statement;

$curDate = new DateTimeImmutable();

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->andWhere(1, '=', '10') //filtering is done of the second column
    ->orWhere('birthdate', fn (string $value): bool => DateTimeImmutable::createFromFormat('Y-m-d', $value) < $curDate) //filtering is done on the `birthdate` column
    ->whereNot('firstname', 'starts_with', 'P') //filtering is done case-sensitively on the first character of the column value
    ->process($reader);
// $records is a League\Csv\ResultSet instance

To enable comparing two columns with each other the following methods are also added: andWhereColumn, whereNotColumn, orWhereColumn and xorWhereColumn

The only distinction with their value counterparts is in the third argument. Instead of specifying a value, it specifies another column (via its string name or integer name) to compare columns with each other.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->andWhereColumn('created_at', '<', 'update_at') //filtering is done on both column value
    ->whereNotColumn('fullname', 'starts_with', 4)   //filtering is done on both column but the second column is specified via its offset
    ->process($reader);
// $records is a League\Csv\ResultSet instance

For complex constraints you can, instead of specifying an simple operator, choose to specificy a callback. In that case the callback method will be evaluated with the value of both columns.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
     ->andWhereColumn('created_at', '<', 'update_at') //filtering is done on both column value
    ->andWhereOffset(
        'fullname', 
        fn (string $valuefirst, string $valueSecond): bool =>  strlen($valuefirst) != strlen($valueSecond), 
        4
    ) 
    ->process($reader);

To enable comparison around the record offset the following methods are also added: andWhereOffset, whereNotOffset, orWhereOffset and xorWhereOffset

The method will only interact with the record offset as such you can only design an operator and the value with which you want to campare the offset with.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->andWhereOffset('<', 100) //filtering is done on the offset value only
    ->process($reader);
// $records is a League\Csv\ResultSet instance

For complex constraint you can, instead of specifying an operator and a value, choose to only specificy a callback. In that case the callback method will be evaluated with the value of the column and/or of its offset.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->andWhereOffset(fn (string|int $value): bool => fmod((float) $value, 2) == 0) 
       // filtering is done on the record offset value
       // records are kept only if the value is even.
    ->process($reader);

For more complex queries you can use the classes and Enums defined under the League\Csv\Query namespace. They are used internally by the Statement class to implement all the new where methods and can be used independently to help create your own where expression as shown in the following example:

use League\Csv\Query;

$data = [
    ['volume' => 67, 'edition' => 2],
    ['volume' => 86, 'edition' => 1],
    ['volume' => 85, 'edition' => 6],
    ['volume' => 98, 'edition' => 2],
    ['volume' => 86, 'edition' => 6],
    ['volume' => 67, 'edition' => 7],
];

$criteria = Query\Constraint\Criteria::xany(
    Query\Constraint\Column::filterOn('volume', 'gt', 80),
    fn (mixed $record, int|string $key) => Query\Row::from($record)->field('edition') < 6
);

$filteredData = array_filter($data, $criteria, ARRAY_FILTER_USE_BOTH));
//Filtering an array using the XOR logical operator

As shown in the example the Criteria class also combines Closure conditions, which means that you can use a callable whose signature matches the one use for the where method.

Ordering

The orderBy method allows you to sort the results of the applied constraints. Just like with filtering the method can be called multiple and the First In First Out rule is also applied. The callable accepted is similar to the one used by the usort function. As an example let’s order the records according to the lastname found on the records.

use League\Csv\Query;
use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->orderBy(fn (mixed $rA, mixed $rB): int => strcmp(Query\Row::from($rB)->field(1) ?? '', Query\Row::from($rA)->field(1) ?? '')))
    ->process($reader);
// $records is a League\Csv\ResultSet instance

Warning: To sort the data iterator_to_array is used, which could lead to a performance penalty if you have a heavy tabular data reader to sort

New since version 9.16.0

The orderByAsc and orderByDesc methods are simpler version of the orderBy method. Instead of requiring a callable, it requires 2 arguments, the tabular data column to sort the document with. It can be as a string (the column name, if it exists) or an integer (the column offset, negative indexes are supported). And an optional callback to improve sorting results if needed. If no callback sorting algorithn is given, sorting is done using the <=> spaceship operator. A sorting callback is a Closure that can be used with PHP’s usort or uasort method.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->orderByDesc(1) //descending order according to the data of the 2nd column
    ->orderByAsc('foo', strcmp(...)) //ascending order according a callback compare function
    ->process($reader);
// $records is a League\Csv\ResultSet instance

if you need to create more complex ordering you may align calls to orderByAsc and orderByDesc or use the orderBy method with the classes defined under the League\Csv\Query namespace as shown below:


use League\Csv\Query;
use League\Csv\Reader;
use League\Csv\Statement;

$sort = Query\Ordering\MultiSort::all(
    Query\Ordering\Column::sortBy(1, 'desc'),
    Query\Ordering\Column::sortBy('foo', 'asc', strcmp(...)),
);

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()->orderBy($sort)->process($reader);
// Will return the same content as in the previous example.

Limit and Offset

You can use the limit and offset methods to limit the number of records returned. When called more than once, only the last filtering setting will be taken into account. The offset specifies an optional offset for the returned data. By default, if no offset is provided the offset equals 0. On the other hand, the limit method specifies an optional maximum records count for the returned data. By default, if no limit is provided the limit equals -1, which translates to all records. We can for instance limit the number of records to at most 5 starting from the 10th found record.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->limit(5)
    ->offset(9)
    ->process($reader);
// $records is a League\Csv\ResultSet instance

When called multiple times, each call overrides the last setting for these options.

Selecting columns

new in version 9.15.0.

You may not always want to select all columns from the tabular data. Using the select method, you can specify which columns to use. The column can be specified by their name, if the instance getHeader returns a non-empty array, or you can default to using the column offset. You can even mix them both.

use League\Csv\Reader;
use League\Csv\Statement;

$reader = Reader::createFromPath('/path/to/file.csv');
$records = Statement::create()
    ->select(1, 3, 'field')
    ->process($reader);
// $records is a League\Csv\ResultSet instance with only 3 fields

While we explain each method separately it is understood that you could use them all together to query your CSV document as you want like in the following example.

use League\Csv\Reader;
use League\Csv\Statement;

$constraints = Statement::create()
    ->select('Integer', 'Text', 'Date and Time')
    ->andWhere('Float', '<', 1.3)
    ->orderByDesc('Integer')
    ->offset(2)
    ->limit(5);

$document = <<<CSV
Integer,Float,Text,Multiline Text,Date and Time
1,1.11,Foo,"Foo
Bar",2020-01-01 01:01:01
2,1.22,Bar,"Bar
Baz",2020-02-02 02:02:02
3,1.33,Baz,"Baz
Foo",2020-03-03 03:03:03
CSV;

$csv = Reader::createFromString($document);
$csv->setHeaderOffset(0);
$csv->addFormatter(fn (array $record) => [...$record, ...['Float' => (float) $record['Float'], 'Integer' => (int) $record['Integer']]])
$records = $constraints->process($csv);
//returns a ResultSet containing records which validate all the constraints.

Since a Statement instance is independent of the CSV document you can re-use it on different CSV documents or TabularDataReader instances if needed.

FragmentFinder

This mechanism is introduced with version 9.12.0.

The second mechanism is based on RFC7111 and allow selecting part of your document according to its rows, columns or cells coordinates. The RFC, and thus, our class assume that your data is column size consistent and, in absence of a specified header, it will use the first record as reference to determine the input number of columns.

The RFC defines three (3) types of selections and the FragmentFinder class supports them all.

You can select part of your data according to:

While this package uses 0-indexed as PHP, the RFC7111 uses 1-indexed to designate columns and rows which might seems inconsistent with the rest of the package.

Here are some selection example:

Of note, the RFC allows for multiple selections, separated by a ;. which are translated as OR expressions. To strictly cover The RFC the class exposes the findAll method which returns an iterable containing the results of all found fragments as distinct TabulatDataReader instances.

If some selections are invalid no error is returned; the invalid selection is skipped from the returned value.

To restrict the returned values you may use the findFirst and findFirstOrFail methods. Both methods return on success a TabularDataReader instance. While the first method always return the first selection found or null; firstOrFail MUST return a TabularDataReader instance or throw. It will also throw if the expression syntax is invalid while all the other methods just ignore the error.

For example, with the following partially invalid expression:

use League\Csv\Reader;
use League\Csv\FragmentFinder;

$reader = Reader::createFromPath('/path/to/file.csv');
$finder = FragmentFinder::create();

$finder->findAll('row=7-5;8-9', $reader);         // return an Iterator<TabularDataReader>
$finder->findFirst('row=7-5;8-9', $reader);       // return an TabularDataReader
$finder->findFirstOrFail('row=7-5;8-9', $reader); // will throw

Both classes, FragmentFinder and Statement returns an instance that implements the TabularDataReader interface which returns the found data in a consistent way.