Sieve

⚗️ Sieve is a simple, clean, and extensible framework for .NET Core that adds sorting, filtering, and pagination functionality out of the box. Most common use case would be for serving ASP.NET Core GET queries.

Get Sieve on nuget

Usage for ASP.NET Core

In this example, consider an app with a Post entity. We'll use Sieve to add sorting, filtering, and pagination capabilities when GET-ing all available posts.

1. Add required services

Inject the SieveProcessor service. So in Startup.cs add:

services.AddScoped<SieveProcessor>();

2. Tell Sieve which properties you'd like to sort/filter in your models

Sieve will only sort/filter properties that have the attribute [Sieve(CanSort = true, CanFilter = true)] on them (they don't have to be both true). So for our Post entity model example:

public int Id { get; set; }

[Sieve(CanFilter = true, CanSort = true)]
public string Title { get; set; }

[Sieve(CanFilter = true, CanSort = true)]
public int LikeCount { get; set; }

[Sieve(CanFilter = true, CanSort = true)]
public int CommentCount { get; set; }

[Sieve(CanFilter = true, CanSort = true, Name = "created")]
public DateTimeOffset DateCreated { get; set; } = DateTimeOffset.UtcNow;

There is also the Name parameter that you can use to have a different name for use by clients.

Alternatively, you can use Fluent API to do the same. This is especially useful if you don't want to use attributes or have multiple APIs. More on Sieve's Fluent API here.

3. Get sort/filter/page queries by using the Sieve model in your controllers

In the action that handles returning Posts, use SieveModel to get the sort/filter/page query. Apply it to your data by injecting SieveProcessor into the controller and using its ApplyAll<TEntity> method. So for instance:

[HttpGet]
public JsonResult GetPosts(SieveModel sieveModel) 
{
    var result = _dbContext.Posts.AsNoTracking(); // Makes read-only queries faster
    result = _sieveProcessor.ApplyAll(sieveModel, result); // Returns `result` after applying the sort/filter/page query in `SieveModel` to it
    return Json(result.ToList());
}

There are also ApplySorting, ApplyFiltering, and ApplyPagination methods.

4. Send a request

Send a request

Add custom sort/filter methods

If you want to add custom sort/filter methods, inject ISieveCustomSortMethods or ISieveCustomFilterMethods with the implementation being a class that has custom sort/filter methods that Sieve will search through.

For instance:

services.AddScoped<ISieveCustomSortMethods, SieveCustomSortMethods>();
services.AddScoped<ISieveCustomFilterMethods, SieveCustomFilterMethods>();

Where SieveCustomSortMethodsOfPosts for example is:

public class SieveCustomSortMethods : ISieveCustomSortMethods
{
    public IQueryable<Post> Popularity(IQueryable<Post> source, bool useThenBy, bool desc) // The method is given an indicator of weather to use ThenBy(), and if the query is descending 
    {
        var result = useThenBy ?
            ((IOrderedQueryable<Post>)source).ThenBy(p => p.LikeCount) : // ThenBy only works on IOrderedQueryable<TEntity>
            source.OrderBy(p => p.LikeCount)
            .ThenBy(p => p.CommentCount)
            .ThenBy(p => p.DateCreated);

        return result; // Must return modified IQueryable<TEntity>
    }
}

And SieveCustomFilterMethods:

public class SieveCustomFilterMethods : ISieveCustomFilterMethods
{
    public IQueryable<Post> IsNew(IQueryable<Post> source, string op, string value) // The method is given the {Operator} & {Value}
    {
        var result = source.Where(p => p.LikeCount < 100 &&
                                        p.CommentCount < 5);

        return result; // Must return modified IQueryable<TEntity>
    }
}

Configure Sieve

Use the ASP.NET Core options pattern with SieveOptions to tell Sieve where to look for configuration. For example:

services.Configure<SieveOptions>(Configuration.GetSection("Sieve"));

Then you can add the configuration:

{
    "Sieve": {
        "CaseSensitive": `boolean: should property names be case-sensitive? Defaults to false`,
        "DefaultPageSize": `int number: optional number to fallback to when no page argument is given. Set <=0 to disable paging if no pageSize is specified (default).`,
        "MaxPageSize": `int number: maximum allowed page size. Set <=0 to make infinite (default)`,
        "ThrowExceptions": `boolean: should Sieve throw exceptions instead of silently failing? Defaults to false`
    }
}

Send a request

With all the above in place, you can now send a GET request that includes a sort/filter/page query. An example:

GET /GetPosts

?sorts=     LikeCount,CommentCount,-created         // sort by likes, then comments, then descendingly by date created 
&filters=   LikeCount>10, Title@=awesome title,     // filter to posts with more than 10 likes, and a title that contains the phrase "awesome title"
&page=      1                                       // get the first page...
&pageSize=  10                                      // ...which contains 10 posts

More formally:

• sorts is a comma-delimited ordered list of property names to sort by. Adding a - before the name switches to sorting descendingly.
• filters is a comma-delimited list of {Name}{Operator}{Value} where
  • {Name} is the name of a property with the Sieve attribute or the name of a custom filter method for TEntity
  • {Operator} is one of the Operators
  • {Value} is the value to use for filtering
• page is the number of page to return
• pageSize is the number of items returned per page

Notes:

• Don't forget to remove commas from any {Value} fields
• You can have spaces anywhere except within {Name} or {Operator} fields
• Here's a good example on how to work with enumerables
• Another example on how to do OR logic

Creating your own DSL

You can replace this DSL with your own (eg. use JSON instead) by implementing an ISieveModel. You can use the default SieveModel for reference.

Operators

Operator	Meaning
==	Equals
!=	Not equals
>	Greater than
<	Less than
>=	Greater than or equal to
<=	Less than or equal to
@=	Contains
_=	Starts with
@=*	Case-insensitive string Contains
_=*	Case-insensitive string Starts with
==*	Case-insensitive string Equals

Handle Sieve's exceptions

Sieve will silently fail unless ThrowExceptions in the configuration is set to true. 3 kinds of custom exceptions can be thrown:

• SieveMethodNotFoundException with a MethodName
• SieveIncompatibleMethodException with a MethodName, an ExpectedType and an ActualType
• SieveException which encapsulates any other exception types in its InnerException

It is recommended that you write exception-handling middleware to globally handle Sieve's exceptions when using it with ASP.NET Core.

Example project

You can find an example project incorporating most Sieve concepts in SieveTests.

License & Contributing

Sieve is licensed under Apache 2.0. Any contributions highly appreciated!