rawsql-ts/dist/esm/transformers/SqlPaginationInjector.js

High-performance SQL parser and AST analyzer written in TypeScript. Provides fast parsing and advanced transformation capabilities.

import { SimpleSelectQuery } from "../models/SelectQuery";
import { LimitClause, OffsetClause } from "../models/Clause";
import { ParameterExpression } from "../models/ValueComponent";
import { SelectQueryParser } from "../parsers/SelectQueryParser";
/**
 * SqlPaginationInjector injects pagination (LIMIT/OFFSET) into a SelectQuery model,
 * creating LIMIT and OFFSET clauses based on provided pagination options.
 */
export class SqlPaginationInjector {
    /**
     * Injects pagination as LIMIT/OFFSET clauses into the given query model.
     * @param query The SelectQuery to modify
     * @param pagination Pagination options containing page number and page size
     * @returns The modified SimpleSelectQuery with pagination applied
     */
    inject(query, pagination) {
        // Validate pagination options
        this.validatePaginationOptions(pagination);
        // Convert string query to SimpleSelectQuery using SelectQueryParser if needed
        if (typeof query === 'string') {
            query = SelectQueryParser.parse(query);
        }
        // Check if query is SimpleSelectQuery
        if (!(query instanceof SimpleSelectQuery)) {
            throw new Error('Complex queries are not supported for pagination');
        }
        // Check if query already has LIMIT or OFFSET clauses
        if (query.limitClause || query.offsetClause) {
            throw new Error('Query already contains LIMIT or OFFSET clause. Use removePagination() first if you want to override existing pagination.');
        }
        // Calculate offset
        const offset = (pagination.page - 1) * pagination.pageSize;
        // Create LIMIT clause
        const limitClause = new LimitClause(new ParameterExpression('paging_limit', pagination.pageSize));
        // Create OFFSET clause (always include for consistent query caching)
        const offsetClause = new OffsetClause(new ParameterExpression('paging_offset', offset));
        // Create a new query with pagination clauses
        return new SimpleSelectQuery({
            withClause: query.withClause,
            selectClause: query.selectClause,
            fromClause: query.fromClause,
            whereClause: query.whereClause,
            groupByClause: query.groupByClause,
            havingClause: query.havingClause,
            orderByClause: query.orderByClause,
            windowClause: query.windowClause,
            limitClause: limitClause,
            offsetClause: offsetClause,
            fetchClause: query.fetchClause,
            forClause: query.forClause,
        });
    }
    /**
     * Removes LIMIT and OFFSET clauses from the given query.
     * @param query The SelectQuery to modify
     * @returns The modified SimpleSelectQuery with pagination removed
     */
    static removePagination(query) {
        // Convert string query to SimpleSelectQuery using SelectQueryParser if needed
        if (typeof query === 'string') {
            query = SelectQueryParser.parse(query);
        }
        // Check if query is SimpleSelectQuery
        if (!(query instanceof SimpleSelectQuery)) {
            throw new Error('Complex queries are not supported for pagination removal');
        }
        // Create a new query without LIMIT and OFFSET clauses
        return new SimpleSelectQuery({
            withClause: query.withClause,
            selectClause: query.selectClause,
            fromClause: query.fromClause,
            whereClause: query.whereClause,
            groupByClause: query.groupByClause,
            havingClause: query.havingClause,
            orderByClause: query.orderByClause,
            windowClause: query.windowClause,
            limitClause: null, // Remove LIMIT
            offsetClause: null, // Remove OFFSET
            fetchClause: query.fetchClause,
            forClause: query.forClause,
        });
    }
    /**
     * Validates pagination options
     * @param pagination Pagination options to validate
     * @throws Error if validation fails
     */
    validatePaginationOptions(pagination) {
        if (!pagination) {
            throw new Error('Pagination options are required');
        }
        if (typeof pagination.page !== 'number' || pagination.page < 1) {
            throw new Error('Page number must be a positive integer (1 or greater)');
        }
        if (typeof pagination.pageSize !== 'number' || pagination.pageSize < 1) {
            throw new Error('Page size must be a positive integer (1 or greater)');
        }
        // Optional: Set reasonable upper limit for page size to prevent performance issues
        if (pagination.pageSize > 1000) {
            throw new Error('Page size cannot exceed 1000 items');
        }
    }
}
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