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This project aims to provide a lightweight ActionFilterAttribute that takes care of sorting and paginating Asp.Net Core API results.

This project is for you if you're still waiting for OData support in Asp.Net Core, even though you only need the most basic of operations. It's also for everyone tired of writing like the 17th string sort = "Username" parameter and lines over lines of switch statements in their controller actions.

It supports EntityFrameworkCores async query materialization with the optional LightQuery.EntityFrameworkCore package.

In addition to the C# client, there's also a client for Angular 5+ on npm: ng-lightquery
Version 1.2.0 and above are compatible with Angular 6+ and rxjs >= 6.0.0.

The package is available on nuget. Daily builds are on myget.

MyGet feed: https://www.myget.org/F/dangl/api/v3/index.json

PM> Install-Package LightQuery

Includes the core functionality to sort and paginate Asp.Net Core controller results

PM> Install-Package LightQuery.EntityFrameworkCore

Includes support for EntityFramework.Core async query materialization

PM> Install-Package LightQuery.Client

Includes LightQuery models and the QueryBuilder utility

NETStandard 2.0 and .Net 4.6.1 are supported.

Tests are run via powershell ./build.ps1 Coverage (or build.sh Coverage) in the root directory.

See below how to apply sorting & filtering to your API controllers. At a glance:

• Return an ObjectResult from your controller with an IQueryable value
• Use sort to sort, page & pageSize for pagination in your requests

You can find a demo in the integration test projects for an example of using this in an Asp.Net Core MVC application for sorting and filtering.

using LightQuery;

public class ApiController : Controller
{
    [LightQuery]
    [ProducesResponseType(typeof(IEnumerable<User>), 200)]
    public IActionResult GetValues()
    {
        var values = _repository.GetAllValuesAsQueryable();
        return Ok(values);  
    }
}

Annotate your controller actions with the LightQueryAttribute and it takes care of applying url queries to the result. All ObjectResults (docs) that have an IQueryable value will be transformed. You're free to return any other results, too, from the annotated action and it will simply be ignored.

Example: http://your.api.com/values?sort=email desc

This will sort the result by its Email property (it is title-cased if no email property is found) in descending order.

You can specifiy a default sort order via the defaultSort parameter of the [LightQuery] attribute. It expects a string that is in the same format as the query string, e.g. defaultSort: "email desc". If relational sorting is active, null checks are introduced.

It is possible to sort by nested properties. This means that properties may be specified in a dotted way to access nested elements, e.g. sorting can be done by using bankAccount.balance. Take this example:

[
    {
        "name": "George",
        "bankAccount": { "balance": 500 }
    },
    {
        "name": "Alice",
        "bankAccount": { "balance": 800 }
    },
    {
        "name": "Bob",
        "bankAccount": null
    }
]

If you apply the sorting expression bankAccount.balance, the user Bob will not be present in the result set because the bankAccount property is null. The query will only be applied to George and Alice.

With v2.0.0, LightQuery introduced a new property wrapNestedSortInNullChecks to the ASP.NET Core controller attributes.

This defaults to false for regular [LightQuery] and to true for [AsyncLightQuery]. It controls whether nested sorting / relational sorting will introduce null checks, e.g. sorting by x.SubProperty.SubId is either translated as .Where(x => x.SubProperty != null).OrderBy(x => x.SubProperty.SubId) or directly as .OrderBy(x => x.SubProperty.SubId). For Entity Framework (using the [AsyncLightQuery] attribute), the database provider usually handles null checking via appropriate join conditions and versions before .NET 5 might produce errors otherwise.

LightQuery supports an additional sort level via the thenSort parameter. For example, take the following url:

`http://your.api.com/values?sort=country&thenSort=email desc`

This would return your values first sorted by the country property and then by the email (descending) property. There is currently no support for multiple thenSort parameters and relational sorting is ignored in thenSort.

Paging is active when the request includes pagination query parameters or via explicitly setting the forcePagination parameter to true in the attributes' constructor. Sorting works in combination with paging.

using LightQuery;

public class ApiController : Controller
{
    [LightQuery(forcePagination: true, defaultPageSize: 3, defaultSort: "columnName desc")]
    [ProducesResponseType(typeof(PaginationResult<User>), 200)]
    public IActionResult GetValues()
    {
        var values = _repository.GetAllValuesAsQueryable();
        return Ok(values);  
    }
}

Example: http://your.api.com/values?sort=email&page=2&pageSize=3

Response

{
    "page": 2,
    "pageSize": 3,
    "totalCount": 20,
    "data": [
        { "userName": "Dave", "email": "[email protected]" },
        { "userName": "Emilia", "email": "[email protected]" },
        { "userName": "Fred", "email": "[email protected]" }
    ]
}

The LightQuery.EntityFrameworkCore package provides an AsyncLightQueryAttribute. This can be used for data sources that support async materialization of queries, e.g. ToListAsync(). To use it, you also need to return just an IQueryable because LightQuery will itself call the async methods when materializing the result.

So, to return a paginatable list of users that is asynchronously materialized, just return something like OK(context.Users).

The LightQuery.Client package contains the PaginationResult<T> base class as well as a QueryBuilder utlity class to construct queries.

Example

using LightQuery.Client;

var url = QueryBuilder.Build(page: 3, pageSize: 25, sortParam: "email");
var response = await _client.GetAsync(url);
var responseContent = await response.Content.ReadAsStringAsync();
var deserializedResponse = JsonConvert.DeserializeObject<PaginationResult<User>>(responseContent);

The LightQuery.Client package contains an abstract class PaginationBaseService<T> that can be used in reactive clients. It is similar in functionality to the TypeScript client.

The npm package ng-lightquery contains client libraries for LightQuery that can be used in Angular 5+ projects. It has a generic PaginationBaseService<T> that your own services can inherit from. As of now, you have to provide a concrete implementation for each generic type argument that you want to use, since the dependency injection in Angular does not currently resolve generics. So if you want two LightQuery services - one to retrieve users and one to retrieve values - you need to create two services yourself.

You'll have three files in this example:

The Angular template which contains an Anguler Material table view.

<md-table [dataSource]="dataSource"
          mdSort
          [mdSortActive]="usersService.sort?.propertyName"
          [mdSortDirection]="usersService.sort?.isDescending ? 'desc' : 'asc'"
          (mdSortChange)="onSort($event)">
    <ng-container cdkColumnDef="email">
        <md-header-cell md-sort-header *cdkHeaderCellDef> Email </md-header-cell>
        <md-cell *cdkCellDef="let row">
            {{row.email}}
        </md-cell>
    </ng-container>
    <md-header-row *cdkHeaderRowDef="['email']"></md-header-row>
    <md-row *cdkRowDef="let row; columns: ['email'];"></md-row>
</md-table>
<md-paginator [length]="usersPaginated.totalCount"
              [pageSize]="usersPaginated.pageSize"
              [pageIndex]="usersPaginated.page - 1"
              (page)="onPage($event)">
</md-paginator>

The component which is backing the view.

export class UsersComponent implements OnInit, OnDestroy {

    constructor(public userService: UserService) { }

    private usersPaginatedSubscription: Subscription;
    usersPaginated: PaginationResult<User>;
    dataSource: DataSource<User>;

    onPage(pageEvent: PageEvent) {
        this.userService.page = pageEvent.pageIndex + 1;
        this.userService.pageSize = pageEvent.pageSize;
    }

    onSort(event: { active: string, direction: string }) {
        if (!event.direction) {
            this.userService.sort = null;
        } else {
            this.userService.sort = { propertyName: event.active, isDescending: event.direction === 'desc' };
        }
    }

    ngOnInit() {
        this.dataSource = this.userService;
        this.usersPaginatedSubscription = this.userService.paginationResult.subscribe(r => this.usersPaginated = r);
    }

    ngOnDestroy() {
        this.usersPaginatedSubscription.unsubscribe();
    }
}

To use the pagination service, simple let your own service inherit from the one provided by the ng-lightquery package via extends PaginationBaseService<T>. You can omit the implementation of the DataSource<User> interface and the connect() and disconnect() methods if you're not working with Angular Material.

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { PaginationBaseService } from 'ng-lightquery';
import { User } from '../models/user';
import { DataSource } from '@angular/cdk/collections';

@Injectable()
export class UsersDetailsService extends PaginationBaseService<User> implements DataSource<User> {

    constructor(protected http: HttpClient) {
      super(http);
      this.baseUrl = '/api/users';
      // You can optionally initialize with some default values,
      // e.g. for sorting, page size or custom url query attributes
      this.sort = {
        isDescending: false,
        propertyName: 'email'
      };
    }

  connect(): Observable<User[]> {
    return this.paginationResult
      .map((r: PaginationResult<User>) => r.data);
  }

  disconnect() { }

}

The packages LightQuery.NSwag and LightQuery.Swashbuckle support the automatic generation of correct Swagger & OpenAPI parameter descriptions for the sort and pagination parameters.

Just add the LightQuery.NSwag.LightQueryOperationsProcessor to your document generation:

services.AddSwaggerDocument(nSwagConfig =>
{
    nSwagConfig.DocumentName = "swagger20";
    nSwagConfig.OperationProcessors.Add(new LightQueryOperationsProcessor());
});
services.AddOpenApiDocument(nSwagConfig =>
{
    nSwagConfig.DocumentName = "openapi30";
    nSwagConfig.OperationProcessors.Add(new LightQueryOperationsProcessor());
});

Just add the LightQuery.Swashbuckle.LightQueryOperationFilter to your document generation:

services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("swagger20", new OpenApiInfo()
    {
        Description = "swagger20"
    });
    options.OperationFilter<LightQueryOperationFilter>();
});

services.AddSwaggerGen(options =>
{
    options.SwaggerDoc("openapi30", new OpenApiInfo()
    {
        Description = "openapi30"
    });
    options.OperationFilter<LightQueryOperationFilter>();
});

This module produces strong named assemblies when compiled. When consumers of this package require strongly named assemblies, for example when they themselves are signed, the outputs should work as-is. The key file to create the strong name is adjacent to the csproj file in the root of the source project. Please note that this does not increase security or provide tamper-proof binaries, as the key is available in the source code per Microsoft guidelines

MIT Licence