Front-end pagination support #449
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| Original file line number | Diff line number | Diff line change |
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| @@ -0,0 +1,212 @@ | ||
| <?php declare(strict_types = 1); | ||
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| namespace RemoteDataBlocks\Editor\DataBinding; | ||
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| use RemoteDataBlocks\Config\Query\QueryInterface; | ||
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| use function add_filter; | ||
| use function add_query_arg; | ||
| use function get_query_var; | ||
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| defined( 'ABSPATH' ) || exit(); | ||
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| class Pagination { | ||
| private static $variable_name = 'rdb-pagination'; | ||
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| public static function init(): void { | ||
| add_filter( 'query_vars', [ __CLASS__, 'register_query_var' ], 10, 1 ); | ||
| } | ||
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| public static function create_query_var( string $query_id, array $pagination_input_variables ): string { | ||
| $value = [ | ||
| $query_id => $pagination_input_variables, | ||
| ]; | ||
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| return add_query_arg( self::$variable_name, self::encode_query_var( $value ) ); | ||
| } | ||
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| private static function decode_query_var( string $query_var_string ): array { | ||
| return json_decode( base64_decode( $query_var_string ), true ) ?? []; | ||
| } | ||
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| private static function encode_query_var( array $query_var_value ): string { | ||
| return base64_encode( wp_json_encode( $query_var_value ) ); | ||
| } | ||
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| public static function get_pagination_input_variables_for_current_request( QueryInterface $query ): array { | ||
| $untrusted_variables = self::decode_query_var( get_query_var( self::$variable_name, '' ) ); | ||
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| if ( empty( $untrusted_variables ) || ! is_array( $untrusted_variables ) ) { | ||
| return []; | ||
| } | ||
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| $query_id = $query->get_id(); | ||
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| // The query var value is an associative array with IDs as keys and | ||
| // values that are an associative array of input variables. | ||
| // | ||
| // We only expect a single key => value pair, but in the future we may | ||
| // decide to support more than one. This would allow us to control the | ||
| // pagination of multiple remote data blocks independently. | ||
| $untrusted_variables = $untrusted_variables[ $query_id ] ?? []; | ||
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| if ( empty( $untrusted_variables ) || ! is_array( $untrusted_variables ) ) { | ||
| return []; | ||
| } | ||
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| // Only accept pagination input variables that are defined in this query's | ||
| // input schema. | ||
| $input_schema = $query->get_input_schema(); | ||
| $input_variables = []; | ||
| $pagination_input_variable_types = [ | ||
| 'ui:pagination_cursor', | ||
| 'ui:pagination_cursor_next', | ||
| 'ui:pagination_cursor_previous', | ||
| 'ui:pagination_offset', | ||
| 'ui:pagination_page', | ||
| 'ui:pagination_per_page', | ||
| ]; | ||
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| foreach ( $input_schema as $slug => $input ) { | ||
| if ( ! in_array( $input['type'] ?? null, $pagination_input_variable_types, true ) ) { | ||
| continue; | ||
| } | ||
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| if ( ! array_key_exists( $slug, $untrusted_variables ) ) { | ||
| continue; | ||
| } | ||
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| $value = $untrusted_variables[ $slug ]; | ||
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| if ( ! is_string( $value ) && ! is_int( $value ) ) { | ||
| continue; | ||
| } | ||
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| $input_variables[ $slug ] = $value; | ||
| } | ||
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| return $input_variables; | ||
| } | ||
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| public static function format_pagination_data_for_query_response( array|null $pagination_data, array $query_input_schema, array $input_variables ): array { | ||
| // If the input schema is empty, it does not support pagination. | ||
| if ( empty( $query_input_schema ) ) { | ||
| return []; | ||
| } | ||
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| // Find the appropriate pagination variables from the input schema. | ||
| $cursor_variable = null; | ||
| $cursor_next_variable = null; | ||
| $cursor_previous_variable = null; | ||
| $offset_variable = null; | ||
| $page_variable = null; | ||
| $per_page_variable = null; | ||
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| foreach ( $query_input_schema as $slug => $input ) { | ||
| $type = $input['type'] ?? ''; | ||
| if ( 'ui:pagination_cursor' === $type ) { | ||
| $cursor_variable = $slug; | ||
| } elseif ( 'ui:pagination_cursor_next' === $type ) { | ||
| $cursor_next_variable = $slug; | ||
| } elseif ( 'ui:pagination_cursor_previous' === $type ) { | ||
| $cursor_previous_variable = $slug; | ||
| } elseif ( 'ui:pagination_offset' === $type ) { | ||
| $offset_variable = $slug; | ||
| } elseif ( 'ui:pagination_page' === $type ) { | ||
| $page_variable = $slug; | ||
| } elseif ( 'ui:pagination_per_page' === $type ) { | ||
| $per_page_variable = $slug; | ||
| } | ||
| } | ||
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| // Default pagination values | ||
| $current_per_page = $input_variables[ $per_page_variable ] ?? 10; | ||
| $pagination_input_variables = []; | ||
| $pagination_type = 'NONE'; | ||
| $total_items = $pagination_data['total_items'] ?? null; | ||
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| $pagination_input_variable_targets = [ | ||
| 'offset' => $offset_variable, | ||
| 'page' => $page_variable, | ||
| 'per_page' => $per_page_variable, | ||
| ]; | ||
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| if ( $cursor_variable ) { | ||
|
There was a problem hiding this comment. Could this logic be documented just above this if statement, or as a function comment? |
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| $pagination_type = 'CURSOR_SIMPLE'; | ||
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| if ( isset( $pagination_data['cursor_next'] ) ) { | ||
| $pagination_input_variables['next_page'] = [ | ||
| $cursor_variable => $pagination_data['cursor_next'], | ||
| ]; | ||
| } | ||
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| if ( isset( $pagination_data['cursor_previous'] ) ) { | ||
| $pagination_input_variables['previous_page'] = [ | ||
| $cursor_variable => $pagination_data['cursor_previous'], | ||
| ]; | ||
| } | ||
| } elseif ( $cursor_next_variable && $cursor_previous_variable ) { | ||
| $pagination_type = 'CURSOR'; | ||
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| if ( isset( $pagination_data['cursor_next'] ) ) { | ||
| $pagination_input_variables['next_page'] = [ | ||
| $cursor_next_variable => $pagination_data['cursor_next'], | ||
| ]; | ||
| } | ||
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| if ( isset( $pagination_data['cursor_previous'] ) ) { | ||
| $pagination_input_variables['previous_page'] = [ | ||
| $cursor_previous_variable => $pagination_data['cursor_previous'], | ||
| ]; | ||
| } | ||
| } elseif ( $offset_variable ) { | ||
| $pagination_type = 'OFFSET'; | ||
| $current_offset = $input_variables[ $offset_variable ] ?? 0; | ||
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| if ( null === $total_items || $current_offset + $current_per_page < $total_items ) { | ||
| $pagination_input_variables['next_page'] = [ | ||
| $offset_variable => $current_offset + $current_per_page, | ||
| ]; | ||
| } | ||
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| if ( $current_offset >= $current_per_page ) { | ||
| $pagination_input_variables['previous_page'] = [ | ||
| $offset_variable => $current_offset - $current_per_page, | ||
| ]; | ||
| } | ||
| } elseif ( $page_variable ) { | ||
| $pagination_type = 'PAGE'; | ||
| $current_page = $input_variables[ $page_variable ] ?? 1; | ||
| $total_pages = $total_items ? ceil( $total_items / $current_per_page ) : null; | ||
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| if ( null === $total_pages || $current_page < $total_pages ) { | ||
| $pagination_input_variables['next_page'] = [ | ||
| $page_variable => $current_page + 1, | ||
| ]; | ||
| } | ||
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| if ( $current_page > 1 ) { | ||
| $pagination_input_variables['previous_page'] = [ | ||
| $page_variable => $current_page - 1, | ||
| ]; | ||
| } | ||
| } | ||
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| if ( 'NONE' === $pagination_type ) { | ||
| return []; | ||
| } | ||
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| return [ | ||
| 'input_variables' => $pagination_input_variables, | ||
| 'input_variable_targets' => $pagination_input_variable_targets, | ||
| 'per_page' => $current_per_page, | ||
| 'total_items' => $total_items, | ||
| 'type' => $pagination_type, | ||
| ]; | ||
| } | ||
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| public static function register_query_var( array $query_vars ): array { | ||
| $query_vars[] = self::$variable_name; | ||
| return $query_vars; | ||
| } | ||
| } | ||
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One of the thoughts I had was to see if we could leverage the UUID from the config instead of doing it this way. But, I see that the problem is this isn't always available like for code based sources (Art Institute being an example of this).
Is there any benefit in changing that, so that all data source configs do have a UUID assigned to them? Then, we could use that UUID here and wherever else we might need to in the future?
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All good if the answer is no, or that it be punted to a future PR. This is just a thought that occurred to me when I tried to experiment with changing it to the UUID, and not seeing it reflect since the Art Institute didn't have one.
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It's a good question. We've discussed both sides. The major downsides of universally requiring UUIDs for all entities are:
Another downside of UUIDs in this use case is that they have no functional value. They are just identifiers. The ID introduced in this PR, by contrast, is deterministic based on the inputs that influence its behavior. This is useful since we are using it to identify external attributes that can be applied to this entity (pagination variables). If the input changes, the ID changes, and it makes sense that the attributes might no longer apply. Meanwhile, a UUID might change for any number of reasons that have nothing to do with the entity's behavior.
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All that said, the main reason that this ID is useful at all is because block instances don't have stable identifiers. If they did, we would use them.