install data table

backend/app/Facades/DataTable/DataTable.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace App\Facades\DataTable;
+
+use App\Services\DataTable\DataTableInput;
+use App\Services\DataTable\DataTableService;
+use Illuminate\Database\Eloquent\Model;
+use Illuminate\Contracts\Database\Query\Builder;
+use Illuminate\Http\Request;
+use App\Services\DataTable\Exceptions\InvalidParameterInterface;
+
+class DataTable
+{
+    /**
+     * Extracts data from request, passes to datatable service and prepares data for response.
+     * @param Model|Builder $mixed
+     * @param Request $request
+     * @param array $allowedFilters
+     * @param array $allowedRelations
+     * @param array $allowedSortings
+     * @param array $allowedSelects
+     * @return array
+     * @throws InvalidParameterInterface if input parameters are invalid.
+     */
+    public function run(
+        Model|Builder $mixed,
+        Request       $request,
+        array         $allowedFilters = [],
+        array         $allowedRelations = [],
+        array         $allowedSortings = [],
+        array         $allowedSelects = [],
+        array         $allowedGroupBy = []
+    ): array
+    {
+
+        $filters = json_decode($request->filters);
+        $sorting = json_decode($request->sorting);
+        $rels = $request->rels ?: array();
+
+        $dataTableInput = new DataTableInput(
+            $request->start,
+            $request->size,
+            $filters,
+            $sorting,
+            $rels,
+            $allowedFilters,
+            $allowedSortings,
+            $allowedGroupBy
+        );
+
+        $query = $this->makeQueryFromModel($mixed);
+
+        $dataTableService = (new DataTableService($query, $dataTableInput))
+            ->setAllowedFilters($allowedFilters)
+            ->setAllowedRelations($allowedRelations)
+            ->setAllowedSortings($allowedSortings)
+            ->setAllowedSelects($allowedSelects)
+            ->setAllowedGroupBy($allowedGroupBy);
+
+        return $dataTableService->getData();
+    }
+
+    protected function makeQueryFromModel(Model|Builder $mixed): Builder
+    {
+        return ($mixed instanceof Model) ? $mixed->query() : $mixed;
+    }
+}

backend/app/Facades/DataTable/DataTableFacade.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace App\Facades\DataTable;
+
+use Illuminate\Support\Facades\Facade;
+
+class DataTableFacade extends Facade
+{
+    protected static function getFacadeAccessor(): string
+    {
+        return DataTable::class;
+    }
+}

backend/app/Providers/DataTableServiceProvider.php

@@ -0,0 +1,27 @@
+<?php
+
+namespace App\Providers;
+
+use App\Facades\DataTable\DataTable;
+use Illuminate\Support\ServiceProvider;
+
+class DataTableServiceProvider extends ServiceProvider
+{
+    /**
+     * Register services.
+     */
+    public function register(): void
+    {
+        $this->app->bind('datatable', function () {
+            return new DataTable();
+        });
+    }
+
+    /**
+     * Bootstrap services.
+     */
+    public function boot(): void
+    {
+        //
+    }
+}

backend/app/Services/DataTable/DataTableInput.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace App\Services\DataTable;
+
+use App\Services\DataTable\Filter\Filter;
+use App\Services\DataTable\Sort\Sort;
+
+class DataTableInput
+{
+    /**
+     * @param int $start
+     * @param int $size
+     * @param array $filters
+     * @param array $sorting
+     * @param array $rels
+     */
+    public function __construct(
+        private ?int   $start,
+        private ?int   $size,
+        private array $filters,
+        private ?array $sorting,
+        private array $rels,
+        private array $allowedFilters,
+        private array $allowedSortings,
+        private ?array $GroupBy,
+    )
+    {
+    }
+
+    public function getStart(): ?int
+    {
+        return $this->start;
+    }
+
+    public function getSize(): ?int
+    {
+        return $this->size;
+    }
+
+    /**
+     * @return array returns an array of Filter objects
+     */
+    public function getFilters(): array
+    {
+        $filters = array();
+
+        foreach ($this->filters as $filter) {
+            $filters[] = new Filter(
+                $filter->id,
+                $filter->value,
+                $filter->fn,
+                $filter->datatype,
+                $this->allowedFilters
+            );
+        }
+
+        return $filters;
+    }
+
+    /**
+     * @return array
+     */
+    public function getSorting(): ?array
+    {
+        $sorts = [];
+        if (!empty($this->sorting)){
+            foreach ($this->sorting as $sort) {
+                $sorts[] =  new Sort($sort->id, $sort->desc, $this->allowedSortings);
+            }
+        }
+        return $sorts;
+    }
+
+    public function getRelations(): array
+    {
+        return $this->rels;
+    }
+
+    public function getGroupBy(): ?array
+    {
+        return $this->GroupBy;
+    }
+}

backend/app/Services/DataTable/DataTableService.php

@@ -0,0 +1,128 @@
+<?php
+
+namespace App\Services\DataTable;
+
+use App\Services\DataTable\Filter\ApplyFilter;
+use App\Services\DataTable\Sort\ApplySort;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class DataTableService
+{
+
+    protected array $allowedFilters;
+    protected array $allowedRelations;
+    protected array $allowedSortings;
+    protected array $allowedSelects;
+    protected array $allowedGroupBy;
+    private int $totalRowCount;
+
+    public function __construct(
+        protected Builder      $query,
+        private DataTableInput $dataTableInput
+    )
+    {
+    }
+
+    public function setAllowedFilters(array $allowedFilters): DataTableService
+    {
+        $this->allowedFilters = $allowedFilters;
+        return $this;
+    }
+
+    public function setAllowedRelations(array $allowedRelations): DataTableService
+    {
+        $this->allowedRelations = $allowedRelations;
+        return $this;
+    }
+
+    public function setAllowedSortings(array $allowedSortings): DataTableService
+    {
+        $this->allowedSortings = $allowedSortings;
+        return $this;
+    }
+
+    public function setAllowedSelects(array $allowedSelects): DataTableService
+    {
+        $this->allowedSelects = $allowedSelects;
+        return $this;
+    }
+
+    public function setAllowedGroupBy(array $allowedGroupBy): DataTableService
+    {
+        $this->allowedGroupBy = $allowedGroupBy;
+        return $this;
+    }
+
+    /**
+     * Handle 'getData' operations
+     * @return array
+     */
+    public function getData(): array
+    {
+        $query = $this->buildQuery();
+        $data = $query->get();
+
+        return array(
+            'data' => $data,
+            'meta' => [
+                'totalRowCount' => $this->totalRowCount
+            ]
+        );
+    }
+
+    protected function buildQuery(): Builder
+    {
+        $query = $this->query;
+
+        foreach ($this->dataTableInput->getFilters() as $filter) {
+            $query = (new ApplyFilter($query, $filter))->apply();
+        }
+
+        $query = $this->applySelect($query, $this->allowedSelects);
+        $query = $this->includeRelationsInQuery($query, $this->allowedRelations);
+        $query = $this->applyGroupBy($query, $this->allowedGroupBy);
+
+        $this->totalRowCount = $query->count();
+
+        if (!is_null($this->dataTableInput->getStart())) {
+            $query->offset($this->dataTableInput->getStart());
+        }
+
+        if(!is_null($this->dataTableInput->getSize())){
+            $query->limit($this->dataTableInput->getSize());
+        }
+
+        $sorting = $this->dataTableInput->getSorting();
+        foreach ($sorting as $sort){
+            $query = (new ApplySort($query, $sort))->apply();
+        }
+
+        return $query;
+    }
+
+    protected function applySelect(Builder $query, array $selectedFields): Builder
+    {
+        if (!empty($selectedFields)) {
+            $query->select($selectedFields);
+        }
+
+        return $query;
+    }
+
+    protected function applyGroupBy(Builder $query, array $groupBy): Builder
+    {
+        return empty($groupBy) ? $query : $query->groupBy($groupBy);
+    }
+
+    protected function includeRelationsInQuery(Builder $query, array $rels): Builder
+    {
+        if (!empty($rels)) {
+            $query->with($rels);
+        }
+
+        return $query;
+    }
+
+    // (later) define mapping of relation names to prevent relation name expose.
+    // (later) define mapping of column names to prevent column name expose.
+}

backend/app/Services/DataTable/Enums/DataType.php

@@ -0,0 +1,15 @@
+<?php
+
+namespace App\Services\DataTable\Enums;
+
+enum DataType: string
+{
+    case NUMERIC = 'numeric';
+    case TEXT = 'text';
+    case DATE = 'date';
+
+    public static function values(): array
+    {
+       return array_column(self::cases(), 'value');
+    }
+}

backend/app/Services/DataTable/Enums/SearchType.php

@@ -0,0 +1,19 @@
+<?php
+
+namespace App\Services\DataTable\Enums;
+
+enum SearchType: string
+{
+    case CONTAINS = 'contains';
+    case EQUALS = 'equals';
+    case NOT_EQUALS = 'notEquals';
+    case BETWEEN = 'between';
+    case GREATER_THAN = 'greaterThan';
+    case LESS_THAN = 'lessThan';
+    case FUZZY = 'fuzzy';
+
+    public static function values(): array
+    {
+       return array_column(self::cases(), 'value');
+    }
+}

backend/app/Services/DataTable/Exceptions/InvalidFilterException.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Services\DataTable\Exceptions;
+
+use Exception;
+
+class InvalidFilterException extends Exception implements InvalidParameterInterface
+{
+    protected $fieldName;
+
+    public function __construct($fieldName, $message = "", $code = 400, \Throwable $previous = null)
+    {
+        $this->fieldName = $fieldName;
+        parent::__construct($message, $code, $previous);
+    }
+
+    public function getFieldName()
+    {
+        return $this->fieldName;
+    }
+}

backend/app/Services/DataTable/Exceptions/InvalidParameterInterface.php

@@ -0,0 +1,7 @@
+<?php
+
+namespace App\Services\DataTable\Exceptions;
+
+interface InvalidParameterInterface
+{
+}

backend/app/Services/DataTable/Exceptions/InvalidRelationException.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Services\DataTable\Exceptions;
+
+use Exception;
+
+class InvalidRelationException extends Exception implements InvalidParameterInterface
+{
+    protected $fieldName;
+
+    public function __construct($fieldName, $message = "", $code = 400, \Throwable $previous = null)
+    {
+        $this->fieldName = $fieldName;
+        parent::__construct($message, $code, $previous);
+    }
+
+    public function getFieldName()
+    {
+        return $this->fieldName;
+    }
+}

backend/app/Services/DataTable/Exceptions/InvalidSortingException.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace App\Services\DataTable\Exceptions;
+
+use Exception;
+
+class InvalidSortingException extends Exception implements InvalidParameterInterface
+{
+    protected $fieldName;
+
+    public function __construct($fieldName, $message = "", $code = 400, \Throwable $previous = null)
+    {
+        $this->fieldName = $fieldName;
+        parent::__construct($message, $code, $previous);
+    }
+
+    public function getFieldName()
+    {
+        return $this->fieldName;
+    }
+}

backend/app/Services/DataTable/Filter/ApplyFilter.php

@@ -0,0 +1,84 @@
+<?php
+
+namespace App\Services\DataTable\Filter;
+
+use App\Services\DataTable\Enums\SearchType;
+use App\Services\DataTable\Exceptions\InvalidFilterException;
+use App\Services\DataTable\Filter\SearchFunctions\FilterBetween;
+use App\Services\DataTable\Filter\SearchFunctions\FilterContains;
+use App\Services\DataTable\Filter\SearchFunctions\FilterEquals;
+use App\Services\DataTable\Filter\SearchFunctions\FilterGreaterThan;
+use App\Services\DataTable\Filter\SearchFunctions\FilterLessThan;
+use App\Services\DataTable\Filter\SearchFunctions\FilterNotEquals;
+use App\Services\DataTable\Filter\SearchFunctions\SearchFilter;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class ApplyFilter
+{
+    private SearchFilter $searchFilter;
+
+    /**
+     * @param Builder $query
+     * @param Filter $filter
+     */
+    public function __construct(
+        private Builder $query,
+        private Filter  $filter,
+    )
+    {
+    }
+
+    public function apply(): Builder
+    {
+        $filter = $this->filter;
+        $query = $this->query;
+
+        $searchType = SearchType::from($filter->getFn());
+        switch ($searchType) {
+            case SearchType::CONTAINS:
+                $this->searchFilter = new FilterContains($query, $filter);
+                break;
+
+            case SearchType::EQUALS:
+                $this->searchFilter = new FilterEquals($query, $filter);
+                break;
+
+            case SearchType::NOT_EQUALS:
+                $this->searchFilter = new FilterNotEquals($query, $filter);
+                break;
+
+            case SearchType::BETWEEN:
+                $this->searchFilter = new FilterBetween($query, $filter);
+                break;
+
+            case SearchType::GREATER_THAN:
+                $this->searchFilter = new FilterGreaterThan($query, $filter);
+                break;
+
+            case SearchType::LESS_THAN:
+                $this->searchFilter = new FilterLessThan($query, $filter);
+                break;
+
+            default:
+                $searchFunction = $filter->getFn();
+                throw new InvalidFilterException($searchFunction, "search function `$searchFunction` is invalid.");
+
+        }
+
+        $relation = $this->filter->getRelation();
+        return method_exists($this->query->getModel(), $relation) ? $this->applyFilterToRelation($relation) : $this->searchFilter->apply();
+    }
+
+    protected function applyFilterToRelation(string $relation): Builder
+    {
+        return $this->query->whereHas($relation, function (Builder $query) {
+            $this->filter->removeRelationFromId();
+            $this->applyFilter($query, $this->filter);
+        });
+    }
+
+    private function applyFilter(Builder $query, Filter $filter): Builder
+    {
+        return (new ApplyFilter($query, $filter))->apply();
+    }
+}

backend/app/Services/DataTable/Filter/Filter.php

@@ -0,0 +1,73 @@
+<?php
+
+namespace App\Services\DataTable\Filter;
+
+use App\Services\DataTable\Validators\FilterValidator;
+
+class Filter
+{
+    private static FilterValidator $filterValidator;
+
+    /**
+     * @param string $id
+     * @param string|int|array $value
+     * @param string $fn
+     * @param string $datatype
+     * @param array $allowedFilters
+     * @throws \App\Services\DataTable\Exceptions\InvalidFilterException
+     */
+    public function __construct(
+        private string           $id,
+        private string|int|array $value,
+        private string           $fn,
+        private string           $datatype,
+        private array $allowedFilters
+    )
+    {
+        self::$filterValidator = FilterValidator::getInstance();
+        self::$filterValidator->isValid($this, $this->allowedFilters);
+    }
+
+    public function getId(): string
+    {
+        return $this->id;
+    }
+
+    public function getValue(): array|int|string
+    {
+        return $this->value;
+    }
+
+    public function getFn(): string
+    {
+        return $this->fn;
+    }
+
+    public function getDatatype(): string
+    {
+        return $this->datatype;
+    }
+
+    public function getRelation(): string
+    {
+        $fieldArray = explode('.', $this->id);
+        return count($fieldArray) > 1 ? $fieldArray[0] : '';
+    }
+
+    public function getColumn(): string
+    {
+        $fieldArray = explode('.', $this->id);
+        return array_pop($fieldArray);
+    }
+
+    public function removeRelationFromId(): void
+    {
+        $this->id = $this->getColumn();
+    }
+
+    public function setValue(int|array|string $value): void
+    {
+        $this->value = $value;
+    }
+
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterBetween.php

@@ -0,0 +1,33 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterBetween extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $query = $this->query;
+        [$minVal, $maxVal] = $this->filter->getValue();
+
+        if ($minVal) {
+            if ($this->filter->getDatatype() == "date") {
+                $minVal = $minVal . " 00:00:00";
+            }
+            $this->filter->setValue($minVal);
+            $query = (new FilterGreaterThanOrEqual($this->query, $this->filter))->apply();
+        }
+
+        if ($maxVal) {
+            if ($this->filter->getDatatype() == "date") {
+                $maxVal = $maxVal . " 23:59:59";
+            }
+            $this->filter->setValue($maxVal);
+            $query = (new FilterLessThanOrEqual($this->query, $this->filter))->apply();
+        }
+
+        return $query;
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterContains.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterContains extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $column = $this->filter->getId();
+        $value = '%' . $this->filter->getValue() . '%';
+
+        if ($this->filter->getDatatype() == DataType::TEXT->value) {
+            $query = $this->searchIgnoreCase($column, $value);
+
+        } else {
+            $query = $this->query->where($column, 'LIKE', $value);
+        }
+
+        return $query;
+    }
+
+    private function searchIgnoreCase(string $column, string $value): Builder
+    {
+        $value = strtolower($value);
+        return $this->query->whereRaw("LOWER($column) LIKE ?", [$value]);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterEquals.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterEquals extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $column = $this->filter->getId();
+        $value = $this->filter->getValue();
+
+        if ($this->filter->getDatatype() == DataType::TEXT->value) {
+            $query = $this->searchIgnoreCase($column, $value);
+        } else {
+            $query = $this->query->where($column, $value);
+        }
+
+        return $query;
+    }
+
+    private function searchIgnoreCase(string $column, string $value): Builder
+    {
+        $value = strtolower($value);
+        return $this->query->whereRaw("LOWER($column) = ?", [$value]);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterGreaterThan.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterGreaterThan extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $value = ($this->filter->getDatatype() == DataType::NUMERIC) ?
+            (float)$this->filter->getValue() : $this->filter->getValue();
+
+        return $this->query->where($this->filter->getId(), '>', $value);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterGreaterThanOrEqual.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterGreaterThanOrEqual extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $value = ($this->filter->getDatatype() == DataType::NUMERIC) ?
+            (float)$this->filter->getValue() : $this->filter->getValue();
+
+        return $this->query->where($this->filter->getId(), '>=', $value);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterLessThan.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterLessThan extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $value = ($this->filter->getDatatype() == DataType::NUMERIC) ?
+            (float)$this->filter->getValue() : $this->filter->getValue();
+
+        return $this->query->where($this->filter->getId(), '<', $value);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterLessThanOrEqual.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Enums\DataType;
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterLessThanOrEqual extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $value = ($this->filter->getDatatype() == DataType::NUMERIC) ?
+            (float)$this->filter->getValue() : $this->filter->getValue();
+
+        return $this->query->where($this->filter->getId(), '<=', $value);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/FilterNotEquals.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use Illuminate\Contracts\Database\Query\Builder;
+
+class FilterNotEquals extends SearchFilter
+{
+
+    public function apply(): Builder
+    {
+        $column = $this->filter->getId();
+        $value = $this->filter->getValue();
+
+        return $this->query->whereNot($column, $value);
+    }
+}

backend/app/Services/DataTable/Filter/SearchFunctions/SearchFilter.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Services\DataTable\Filter\SearchFunctions;
+
+use App\Services\DataTable\Filter\Filter;
+use Illuminate\Contracts\Database\Query\Builder;
+
+abstract class SearchFilter
+{
+    /**
+     * @param Builder $query
+     * @param Filter $filter
+     */
+    public function __construct(
+        protected Builder $query,
+        protected Filter  $filter,
+    )
+    {
+    }
+
+    abstract public function apply(): Builder;
+}

backend/app/Services/DataTable/Sort/ApplySort.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace App\Services\DataTable\Sort;
+
+use Illuminate\Contracts\Database\Query\Builder;
+
+class ApplySort
+{
+
+    /**
+     * @param Builder $query
+     * @param ?Sort $sort
+     */
+    public function __construct(
+        private Builder $query,
+        private ?Sort    $sort,
+    )
+    {
+    }
+
+    public function apply(): Builder
+    {
+        $query = $this->query;
+
+        if (!is_null($this->sort)) {
+            $query->orderBy($this->sort->getId(), $this->sort->getDirection());
+        }
+
+        return $query;
+    }
+}

backend/app/Services/DataTable/Sort/Sort.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Services\DataTable\Sort;
+
+use App\Services\DataTable\Validators\SortingValidator;
+
+class Sort
+{
+    private static SortingValidator $sortingValidator;
+
+    /**
+     * @param string $id
+     * @param bool $desc
+     * @param array $allowedSortings
+     * @throws \App\Services\DataTable\Exceptions\InvalidSortingException
+     */
+    public function __construct(
+        private string $id,
+        private bool   $desc,
+        private array $allowedSortings,
+    )
+    {
+        self::$sortingValidator = SortingValidator::getInstance();
+        self::$sortingValidator->isValid($this, $this->allowedSortings);
+    }
+
+    /**
+     * @return string
+     */
+    public function getId(): string
+    {
+        return $this->id;
+    }
+
+    public function getDirection(): string
+    {
+        return $this->desc === true ? 'desc' : 'asc';
+    }
+}

backend/app/Services/DataTable/Validators/FilterValidator.php

@@ -0,0 +1,69 @@
+<?php
+
+namespace App\Services\DataTable\Validators;
+
+use App\Services\DataTable\Enums\SearchType;
+use App\Services\DataTable\Enums\DataType;
+use App\Services\DataTable\Exceptions\InvalidFilterException;
+use App\Services\DataTable\Filter\Filter;
+
+class FilterValidator
+{
+    private static $instance;
+
+    private function __construct()
+    {
+    }
+
+    public static function getInstance(): FilterValidator
+    {
+        if (!isset(self::$instance)) {
+            self::$instance = new static();
+        }
+
+        return self::$instance;
+    }
+
+    public function isValid(Filter $filter, array $allowedFilters): bool
+    {
+        if (!$this->isAllowed($filter, $allowedFilters)) {
+            $filterId = $filter->getId();
+            throw new InvalidFilterException($filter->getId(), "filtering field `$filterId` is not allowed.");
+        }
+
+        if (!$this->isValidSearchFunction($filter)) {
+            $searchFunction = $filter->getFn();
+            throw new InvalidFilterException($searchFunction, "search function `$searchFunction` is invalid.");
+        }
+
+        if ($this->isValidDataType($filter) == -1) {
+            throw new InvalidFilterException(null, "datatype property is not set in `filters` array.");
+        }
+
+        if (!$this->isValidDataType($filter)) {
+            $datatype = $filter->getDatatype();
+            throw new InvalidFilterException($datatype, "datatype `$datatype` is invalid.");
+        }
+
+        return true;
+    }
+
+    protected function isAllowed(Filter $filter, array $allowedFilters): bool
+    {
+        return $allowedFilters == ['*'] || in_array($filter->getId(), $allowedFilters);
+    }
+
+    protected function isValidSearchFunction(Filter $filter): bool
+    {
+        $searchFunction = $filter->getFn();
+        return isset($searchFunction) && in_array($searchFunction, SearchType::values());
+    }
+
+    protected function isValidDataType(Filter $filter): int
+    {
+        if (!property_exists($filter, 'datatype'))
+            return -1;
+
+        return $filter->getDatatype() && in_array($filter->getDatatype(), DataType::values()) ? 1 : 0;
+    }
+}

backend/app/Services/DataTable/Validators/RelationValidator.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace App\Services\DataTable\Validators;
+
+use App\Services\DataTable\Exceptions\InvalidRelationException;
+
+class RelationValidator
+{
+    public static function validate(?array $rels, array $allowedRelations): bool
+    {
+        foreach ($rels as $relation) {
+
+            if (!self::isAllowed($relation, $allowedRelations)) {
+                throw new InvalidRelationException($relation, "relation `$relation` is not allowed.");
+            }
+        }
+
+        return true;
+    }
+
+    public static function isAllowed(string $relation, array $allowedRelations): bool
+    {
+        return !$relation || in_array($relation, $allowedRelations);
+    }
+}

backend/app/Services/DataTable/Validators/SortingValidator.php

@@ -0,0 +1,39 @@
+<?php
+
+namespace App\Services\DataTable\Validators;
+
+use App\Services\DataTable\Exceptions\InvalidSortingException;
+use App\Services\DataTable\Sort\Sort;
+
+class SortingValidator
+{
+    private static $instance;
+
+    private function __construct()
+    {
+    }
+
+    public static function getInstance(): SortingValidator
+    {
+        if (!isset(self::$instance)) {
+            self::$instance = new static();
+        }
+
+        return self::$instance;
+    }
+
+    public function isValid(Sort $sorting, array $allowedSortings): bool
+    {
+        if (!$this->isAllowed($sorting, $allowedSortings)) {
+            $sortId = $sorting->getId();
+            throw new InvalidSortingException($sortId, "sorting field `$sortId` is not allowed.");
+        }
+
+        return true;
+    }
+
+    protected function isAllowed(Sort $sorting, array $allowedSortings): bool
+    {
+        return $allowedSortings == ['*'] || in_array($sorting->getId(), $allowedSortings);
+    }
+}

backend/bootstrap/providers.php

@@ -1,7 +1,6 @@
 <?php
 
-use App\Providers\AppServiceProvider;
-
 return [
-    AppServiceProvider::class,
+    App\Providers\AppServiceProvider::class,
+    App\Providers\DataTableServiceProvider::class,
 ];