Pagination in TypeORM/NestJS

Question

. 。 Answers to this question are eligible for a +50 reputation bounty. Niharika S wants to to this question: 这个问题：

Please help me. I am not able to resolve the same. if you need code I can provide the same.

I have to introduce pagination in findAll() method. I really dont know how to do it. I tried but it is giving so many errors. I used findAndCount() method given by typeorm for that, But I am not sure how it will work.

As of now below method returning all the record. I need to return at a time 10 records. Please suggest what modification I need to do.

async findAll(queryCertificateDto: QueryCertificateDto,page=1):  Promise<PaginatedResult> {
    
    let { country, sponser } = queryCertificateDto;

    const query = this.certificateRepository.createQueryBuilder('certificate');

    if (sponser) {
        sponser = sponser.toUpperCase();
        query.andWhere('Upper(certificate.sponser)=:sponser', { sponser });
    }

    if (country) {
        country = country.toUpperCase();
        query.andWhere('Upper(certificate.country)=:country', { country });
    }      
    const  certificates = query.getMany();     
    return certificates;
}

this is PaginatedResult file.

 export class PaginatedResult {
        data: any[];
        meta: {
          total: number;
          page: number;
          last_page: number;
        };
      }
  

I tried changing code of findAll() but where clause is giving error. I am not sure how to handle query.getMany() in pagination .

 const take = query.take || 10
        const skip = query.skip || 0
       
      
        const [result, total] = await this.certificateRepository.findAndCount(
            {
                where: query.getMany(),   //this is giving error
                take:take,
                skip:skip
            }
        );
        return result;

I need to introduce pagination in this method. Any help will be really helpful.

Answer 1

Typeorm has a really nice method specific to your usecase findAndCount

async findAll(queryCertificateDto: QueryCertificateDto):  Promise<PaginatedResult> {

    const take = queryCertificateDto.take || 10
    const skip = queryCertificateDto.skip || 0
    const country = queryCertificateDto.keyword || ''
    const sponser = queryCertificateDto.sponser || ''
    

    const query = this.certificateRepository.createQueryBuilder('certificate');

    const [result, total] = await this.certificateRepository.findAndCount(
        {
            where: { country: Like('%' + country + '%') AND sponser: Like('%' + sponser + '%') }, order: { name: "DESC" },
            take: take,
            skip: skip
        }
    );
     
    return {
        data: result,
        count: total
    };
}

More documentation about Repository class can be found here

Answer 2

you don't need the .getmany() with your where in the last code, the result is an array of the data you need.

from your first code, you can do this

async findAll(queryCertificateDto: QueryCertificateDto,page=1): Promise<PaginatedResult> {
    //let's say limit and offset are passed here too
    let { country, sponser, limit, offset } = queryCertificateDto;


    const query = this.certificateRepository.createQueryBuilder('certificate');

    if (sponser) {
        sponser = sponser.toUpperCase();
        query.andWhere('certificate.sponser = :sponser', { sponser });
    }

    if (country) {
        country = country.toUpperCase();
        query.andWhere('certificate.country = :country', { country });
    } 
    //limit and take mean the same thing, while skip and offset mean the 
    same thing

    const  certificates = await query
                               .offset(offset || 0)
                               .limit(limit || 10)
                               .getMany();

    // if you want to count just replace the `.getMany()` with 
    ```.getManyandCount()```;

    return certificates;
}```