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Installation

The request package can be installed independently or as part of the full CRUD framework: 
npm install @nestjsx/crud-request
If you install @nestjsx/crud, this package is automatically included as a dependency. You only need to install it separately if you want to use the query builder in a standalone project.

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Automatic Dependencies

The following packages are automatically installed:
  • @nestjsx/util - Shared utility functions
  • qs - Query string parsing and stringification

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Usage in Frontend Applications

This package is particularly useful in frontend applications for building API queries:

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Basic Setup

import { RequestQueryBuilder } from '@nestjsx/crud-request';

// Create a query builder instance
const qb = RequestQueryBuilder.create();

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Building Simple Queries

import { RequestQueryBuilder } from '@nestjsx/crud-request';

// Simple search
const query = RequestQueryBuilder.create()
  .search({ name: 'John' })
  .query();

// Result: "?s={\"name\":\"John\"}"

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Building Complex Queries

import { RequestQueryBuilder, CondOperator } from '@nestjsx/crud-request';

const query = RequestQueryBuilder.create()
  .search({
    status: 'active',
    role: 'admin'
  })
  .setFilter({
    field: 'age',
    operator: CondOperator.GREATER_THAN,
    value: 18
  })
  .sortBy([
    { field: 'createdAt', order: 'DESC' },
    { field: 'name', order: 'ASC' }
  ])
  .setLimit(20)
  .setPage(1)
  .setJoin({ field: 'profile' })
  .query();

// Use with your HTTP client
const response = await fetch(`/api/users${query}`);

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Common Query Patterns

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Pagination

const query = RequestQueryBuilder.create()
  .setLimit(10)
  .setPage(1)
  .query();

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Sorting

const query = RequestQueryBuilder.create()
  .sortBy({ field: 'name', order: 'ASC' })
  .query();

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Filtering

import { CondOperator } from '@nestjsx/crud-request';

const query = RequestQueryBuilder.create()
  .setFilter({
    field: 'email',
    operator: CondOperator.CONTAINS,
    value: '@example.com'
  })
  .query();

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Relations

const query = RequestQueryBuilder.create()
  .setJoin([
    { field: 'profile' },
    { field: 'posts' }
  ])
  .query();

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Field Selection

const query = RequestQueryBuilder.create()
  .select(['id', 'name', 'email'])
  .query();

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Usage in Backend Applications

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Automatic Parsing

When using @nestjsx/crud, request parsing happens automatically: 
import { Controller } from '@nestjs/common';
import { Crud, CrudRequest, ParsedRequest } from '@nestjsx/crud';

@Crud({
  model: { type: User }
})
@Controller('users')
export class UserController {
  constructor(public service: UserService) {}
  
  // Access parsed request in overridden methods
  @Override()
  getMany(@ParsedRequest() req: CrudRequest) {
    // req.parsed contains the parsed query
    return this.service.getMany(req);
  }
}

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Manual Parsing

You can also parse queries manually: 
import { RequestQueryParser } from '@nestjsx/crud-request';

const parser = RequestQueryParser.create();
const parsed = parser.parseQuery({
  fields: 'id,name,email',
  sort: 'name,ASC',
  limit: '10',
  page: '1'
});

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Integration with HTTP Clients

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Axios

import axios from 'axios';
import { RequestQueryBuilder } from '@nestjsx/crud-request';

const query = RequestQueryBuilder.create()
  .search({ status: 'active' })
  .query();

const response = await axios.get(`/api/users${query}`);

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Fetch API

import { RequestQueryBuilder } from '@nestjsx/crud-request';

const query = RequestQueryBuilder.create()
  .setLimit(20)
  .query();

const response = await fetch(`/api/users${query}`);
const data = await response.json();

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Angular HttpClient

import { HttpClient } from '@angular/common/http';
import { RequestQueryBuilder } from '@nestjsx/crud-request';

const query = RequestQueryBuilder.create()
  .sortBy({ field: 'name', order: 'ASC' })
  .query();

this.http.get(`/api/users${query}`).subscribe(data => {
  console.log(data);
});

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TypeScript Support

The package includes full TypeScript definitions: 
import { 
  RequestQueryBuilder,
  CondOperator,
  QueryFilter,
  QuerySort,
  QueryJoin 
} from '@nestjsx/crud-request';

// Type-safe filter
const filter: QueryFilter = {
  field: 'age',
  operator: CondOperator.GREATER_THAN,
  value: 18
};

// Type-safe sort
const sort: QuerySort = {
  field: 'name',
  order: 'ASC'
};

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Available Operators

The package provides the following filter operators:
  • EQUALS - Equal to
  • NOT_EQUALS - Not equal to
  • GREATER_THAN - Greater than
  • LOWER_THAN - Less than
  • GREATER_THAN_EQUALS - Greater than or equal
  • LOWER_THAN_EQUALS - Less than or equal
  • STARTS - Starts with
  • ENDS - Ends with
  • CONTAINS - Contains
  • EXCLUDES - Excludes
  • IN - In array
  • NOT_IN - Not in array
  • IS_NULL - Is null
  • NOT_NULL - Is not null
  • BETWEEN - Between values

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Next Steps

Core Package

Learn about the core CRUD package

TypeORM Integration

Add TypeORM for database operations

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Troubleshooting

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Query String Too Long

If your query strings are getting too long, consider:
  • Using POST requests for complex filters
  • Implementing server-side saved filters
  • Breaking down complex queries into multiple requests

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TypeScript Errors

Ensure your tsconfig.json includes: 
{
  "compilerOptions": {
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true
  }
}

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