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I want to implement search, filter and pagination capabilities for a model I created in Loopback 4. I have the default 7 CRUD apis for the model I created, all thoughs work fine.

Now I want to add the list capabilities(search, filter pagination etc) how to implement that there is no proper documentation for this in Loopback 4 docs. Can anybody please help me implement that.

Thanks

Yash Rahurikar
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2 Answers2

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Yes, the documentation is incomplete but seems like they are working on it.

Meanwhile, you can try find() on a repository with where and or parameters together. For pagination, offset and limit parameters work fine. More details on filter available here on their docs. Details on CrudConnector.find() method is available here.

For your reference, I'll attach my piece of code and use it as you wish.

/**
   * customer.repository.ts
   * mongodb datasource
   * @param [searchKey] Search in `firstName`, `lastName`, or `email`
   * @param [pageIndex] page number. If provided, `pageSize` is required
   * @param [pageSize] records per page. If provided, `pageIndex` is required
   * @returns {CustomerInfoInterface[]} List of customers sorted by `firstName`
   */
  async getCustomerList(searchKey?: string, pageIndex?: number, pageSize?: number): Promise<CustomerInfoInterface[]> {
    const searchParam = searchKey || '';
    const searchParams = [
      {firstName: {like: searchParam, options: 'i'}},
      {lastName: {like: searchParam, options: 'i'}},
      {email: {like: searchParam, options: 'i'}},
    ];
    var filterObject = {where: {or: searchParams}, order: ['firstName ASC']};
    if (pageIndex && pageSize) {
      const offset = (pageIndex - 1) * pageSize;
      const limit = pageSize;
      filterObject = Object.assign(filterObject, {limit, offset});
    }
    logger.debug('search user list with search query');
    logger.debug(filterObject);
    const customerList = await this.find(filterObject);
    return customerList.map(i => ({
      customerId: i.customerId,
      firstName: i.firstName,
      lastName: i.lastName,
      phone: i.phone,
      address: i.address,
      id: i.customerId,
    }));
  }
Salitha
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  • From where are you getting searchKey, pageIndex and pageSize ? – Yash Rahurikar Sep 16 '19 at 06:34
  • In order to search do I have to insert the exact same value for the search field ? for example, filter[where][name]=John Doe Can't I just search John and it should give me the result, but right now it gives me an empty response when I just search for John is there any way ? – Yash Rahurikar Sep 16 '19 at 06:51
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    This is a function that performs search and return a promise (array). So you need to call it from somewhere else. I'm calling it from the controller. You **do not** need to put **exact** same value. Read MongoDB documentations. Please note that my code is not exactly what you want. so you need to understand the concept and implement your own. good luck – Salitha Sep 16 '19 at 07:13
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As mentioned in the other answer, the documentation for LoopBack 4 is not complete yet.

For searching and filtering records, LoopBack 4 uses the same query syntax as LoopBack 3, both at the TypeScript level (see the type definitions in loopback-datasource-juggler's file query.d.ts) and REST API level (via controllers scaffolded by lb4 controller command).

As a result, most of the LoopBack 3 documentation applies to LoopBack 4 too. See Filters section in Querying data to get started, check sub-pages like Where filter for more information on different filtering fields.

Miroslav Bajtoš
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  • Where should I write the filters ? in controllers ? – Yash Rahurikar Sep 16 '19 at 06:30
  • In order to search do I have to insert the exact same value for the search field ? for example, filter[where][name]=John Doe Can't I just search John and it should give me the result, but right now it gives me an empty response when I just search for John is there any way ? – Yash Rahurikar Sep 16 '19 at 06:53
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    LoopBack uses equality operator by default. `filter[where][name]=John Doe` returns all records where name is exactly `John Doe`. Use `like` or `ilike` to specific a more complex match. See https://loopback.io/doc/en/lb3/Where-filter.html#like-and-nlike – Miroslav Bajtoš Sep 16 '19 at 10:00