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| export class QueryBuilder<T> {
private _select: string[] = [];
private _from: string = '';
private _joins: JoinClause[] = [];
private _where: WhereClause[] = [];
private _orderBy: OrderByClause[] = [];
private _limit?: number;
private _offset?: number;
private _alias: string = 't';
private _aliasCounter: number = 1;
constructor(
private entity: EntityClass<T>,
private connection: Connection
) {
const metadata = entityMetadata.get(entity);
if (metadata) {
this._from = metadata.tableName;
}
}
selectAll(): QueryBuilder<T> {
const metadata = entityMetadata.get(this.entity);
if (metadata) {
metadata.columns.forEach((column, property) => {
this._select.push(`${this._alias}.${column.columnName}`);
});
}
return this;
}
select<K extends keyof T>(...fields: K[]): QueryBuilder<Pick<T, K>> {
const metadata = entityMetadata.get(this.entity);
if (metadata) {
fields.forEach(field => {
const column = metadata.columns.get(field as string);
if (column) {
this._select.push(`${this._alias}.${column.columnName}`);
}
});
}
return this as any;
}
selectAs<K extends keyof T, A extends string>(
field: K,
alias: A
): QueryBuilder<T & Record<A, T[K]>> {
const metadata = entityMetadata.get(this.entity);
if (metadata) {
const column = metadata.columns.get(field as string);
if (column) {
this._select.push(`${this._alias}.${column.columnName} AS ${alias}`);
}
}
return this as any;
}
eq<K extends keyof T>(field: K, value: T[K]): QueryBuilder<T> {
return this.where(field, '=', value);
}
like<K extends keyof T>(field: K, value: string): QueryBuilder<T> {
return this.where(field, 'LIKE', value);
}
gt<K extends keyof T>(field: K, value: T[K]): QueryBuilder<T> {
return this.where(field, '>', value);
}
where<K extends keyof T>(field: K, operator: string, value: T[K]): QueryBuilder<T> {
const metadata = entityMetadata.get(this.entity);
if (metadata) {
const column = metadata.columns.get(field as string);
if (column) {
this._where.push({
field: `${this._alias}.${column.columnName}`,
operator,
value,
logic: 'AND'
});
}
}
return this;
}
leftJoin<R>(
entity: EntityClass<R>,
condition: (left: T, right: R) => JoinCondition
): JoinQueryBuilder<T, R> {
const rightAlias = `t${this._aliasCounter++}`;
const rightMetadata = entityMetadata.get(entity);
if (rightMetadata) {
this._joins.push({
type: 'LEFT',
table: rightMetadata.tableName,
alias: rightAlias,
condition: condition as any
});
}
return new JoinQueryBuilder(this, entity, rightAlias);
}
orderBy<K extends keyof T>(field: K, direction: 'ASC' | 'DESC' = 'ASC'): QueryBuilder<T> {
const metadata = entityMetadata.get(this.entity);
if (metadata) {
const column = metadata.columns.get(field as string);
if (column) {
this._orderBy.push({
field: `${this._alias}.${column.columnName}`,
direction
});
}
}
return this;
}
limit(count: number): QueryBuilder<T> {
this._limit = count;
return this;
}
offset(count: number): QueryBuilder<T> {
this._offset = count;
return this;
}
toSQL(): { sql: string; params: any[] } {
let sql = 'SELECT ';
if (this._select.length > 0) {
sql += this._select.join(', ');
} else {
sql += '*';
}
sql += ` FROM ${this._from} ${this._alias}`;
this._joins.forEach(join => {
sql += ` ${join.type} JOIN ${join.table} ${join.alias} ON ${join.condition}`;
});
const params: any[] = [];
if (this._where.length > 0) {
sql += ' WHERE ';
const whereConditions = this._where.map(clause => {
params.push(clause.value);
return `${clause.field} ${clause.operator} ?`;
});
sql += whereConditions.join(' AND ');
}
if (this._orderBy.length > 0) {
sql += ' ORDER BY ';
const orderConditions = this._orderBy.map(clause =>
`${clause.field} ${clause.direction}`
);
sql += orderConditions.join(', ');
}
if (this._limit !== undefined) {
sql += ` LIMIT ${this._limit}`;
}
if (this._offset !== undefined) {
sql += ` OFFSET ${this._offset}`;
}
return { sql, params };
}
async getMany(): Promise<T[]> {
const { sql, params } = this.toSQL();
const [rows] = await this.connection.execute(sql, params);
return this.mapRowsToEntities(rows as any[]);
}
async getOne(): Promise<T | null> {
this.limit(1);
const results = await this.getMany();
return results.length > 0 ? results[0] : null;
}
async getCount(): Promise<number> {
let sql = `SELECT COUNT(*) as count FROM ${this._from} ${this._alias}`;
this._joins.forEach(join => {
sql += ` ${join.type} JOIN ${join.table} ${join.alias} ON ${join.condition}`;
});
const params: any[] = [];
if (this._where.length > 0) {
sql += ' WHERE ';
const whereConditions = this._where.map(clause => {
params.push(clause.value);
return `${clause.field} ${clause.operator} ?`;
});
sql += whereConditions.join(' AND ');
}
const [rows] = await this.connection.execute(sql, params);
return (rows as any[])[0].count;
}
private mapRowsToEntities(rows: any[]): T[] {
const metadata = entityMetadata.get(this.entity);
if (!metadata) return [];
return rows.map(row => {
const entity = new (this.entity as any)();
metadata.columns.forEach((column, property) => {
if (row[column.columnName] !== undefined) {
(entity as any)[property] = row[column.columnName];
}
});
return entity;
});
}
}
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