QueryKit is a .NET library that makes it easier to query your data by providing a fluent and intuitive syntax for filtering and sorting.
$ dotnet add package QueryKitQueryKit is a .NET library that makes it easier to query your data by providing a fluent and intuitive syntax for filtering and sorting. The main use case is a lighter weight subset of OData or GraphQL for parsing external filtering and sorting inputs to provide more granular consumption (e.g. a React UI provides filtering controls to filter a worklist). It's inspired by Sieve, but with some differences.
dotnet add package QueryKit
If we wanted to apply a filter to a DbSet called People, we just have to do something like this:
var filterInput = """FirstName == "Jane" && Age > 10""";
var people = _dbContext.People
.ApplyQueryKitFilter(filterInput)
.ToList();
QueryKit will automatically translate this into an expression for you. You can even customize your property names:
var filterInput = """first == "Jane" && Age > 10""";
var config = new QueryKitConfiguration(config =>
{
config.Property<Person>(x => x.FirstName).HasQueryName("first");
});
var people = _dbContext.People
.ApplyQueryKitFilter(filterInput, config)
.ToList();
Sorting works too:
var filterInput = """first == "Jane" && Age > 10""";
var config = new QueryKitConfiguration(config =>
{
config.Property<Person>(x => x.FirstName).HasQueryName("first");
});
var people = _dbContext.People
.ApplyQueryKitFilter(filterInput, config)
.ApplyQueryKitSort("first, Age desc", config)
.ToList();
And that's the basics! There's no services to inject or global set up to worry about, just apply what you want and call it a day. For a full list of capables, see below.
To apply filters to your queryable, you just need to pass an input string with your filtering input to ApplyQueryKitFilter off of a queryable:
var people = _dbContext.People.ApplyQueryKitFilter("Age < 10").ToList();
You can also pass a configuration like this. More on configuration options below.
var config = new QueryKitConfiguration(config =>
{
config.Property<SpecialPerson>(x => x.FirstName)
.HasQueryName("first")
.PreventSort();
});
var people = _dbContext.People
.ApplyQueryKitFilter(@$"first == "Jane" && Age < 10", config)
.ToList();
When filtering, you can use logical operators && for and as well as || for or. For example:
var input = """FirstName == "Jane" && Age < 10""";
var input = """FirstName == "Jane" || FirstName == "John" """;You can use order of operation with parentheses like this:
var input = """(FirstName == "Jane" && Age < 10) || FirstName == "John" """;There's a wide variety of comparison operators that use the same base syntax as Sieve's operators. To do a case-insensitive operation, just append a * at the end of the operator.
| Name | Operator | Case Insensitive Operator | Count Operator |
|---|---|---|---|
| Equals | == | ==* | #== |
| Not Equals | != | !=* | #!= |
| Greater Than | > | N/A | #> |
| Less Than | < | N/A | #< |
| Greater Than Or Equal | >= | N/A | #>= |
| Less Than Or Equal | <= | N/A | #<= |
| Starts With | _= | _=* | N/A |
| Does Not Start With | !_= | !_=* | N/A |
| Ends With | _-= | _-=* | N/A |
| Does Not End With | !_-= | !_-=* | N/A |
| Contains | @= | @=* | N/A |
| Does Not Contain | !@= | !@=* | N/A |
| Sounds Like | ~~ | N/A | N/A |
| Does Not Sound Like | !~ | N/A | N/A |
| Has | ^$ | ^$* | N/A |
| Does Not Have | !^$ | !^$* | N/A |
| In | ^^ | ^^* | N/A |
| Not In | !^^ | !^^* | N/A |
Sounds LikeandDoes Not Sound Likerequires a soundex configuration on your DbContext. For more info see the docs below
Here's an example for the in operator:
var input = """(Age ^^ [20, 30, 40]) && (BirthMonth ^^* ["January", "February", "March"]) || (Id ^^ ["6d623e92-d2cf-4496-a2df-f49fa77328ee"])""";string and guid properties should be wrapped in double quotes
null doesn't need quotes: var input = "Title == null";
Double quotes can be escaped by using a similar syntax to raw-string literals introduced in C#11:
var input = """""Title == """lamb is great on a "gee-ro" not a "gy-ro" sandwich""" """"";
// OR
var input = """""""""Title == """"lamb is great on a "gee-ro" not a "gy-ro" sandwich"""" """"""""";
Dates and times use ISO 8601 format and should be surrounded by double quotes:
DateOnly: var filterInput = """Birthday == "2022-07-01" """;
DateTimeOffset:
var filterInput = """Birthday == "2022-07-01T00:00:03Z" """;DateTime: var filterInput = """Birthday == "2022-07-01" """;
var filterInput = """Birthday == "2022-07-01T00:00:03" """;var filterInput = """Birthday == "2022-07-01T00:00:03+01:00" """;TimeOnly:
var filterInput = """Time == "12:30:00" """;var filterInput = """Time == "12:30:00.678722" """;bool properties need to use == true, == false, or the same using the != operator. they can not be standalone properies:
var input = """Title == "chicken & waffles" && Favorite""";var input = """Title == "chicken & waffles" && Favorite == true""";var input = """(Title == "lamb" && ((Age >= 25 && Rating < 4.5) || (SpecificDate <= "2022-07-01T00:00:03Z" && Time == "00:00:03")) && (Favorite == true || Email.Value _= "hello@gmail.com"))""";QueryKit supports comparing one property directly to another property on the same entity. This allows for dynamic filtering where the comparison value is another field rather than a literal value:
// Compare two string properties
var input = """FirstName == LastName""";
// Compare numeric properties
var input = """Age > Rating""";
// Use in complex expressions
var input = """(FirstName != LastName && Age > Rating) || (Score1 <= Score2)""";
// Combine with regular filters
var input = """FirstName == LastName && Age > 21""";Property-to-property comparisons work with all comparison operators and automatically handle type conversions between compatible numeric types (e.g., comparing int with decimal).
You can also compare child properties to root properties or other child properties:
// Compare child property to root property
var input = """Author.Name == Title""";
// Compare nested child properties
var input = """Email.Value == CollectionEmail.Value""";
// Mix child and root properties in complex expressions
var input = """Author.Name != Title && Rating > Author.Score""";Child property comparisons work with:
Author.Name, Email.Value==, !=, >, <, >=, <=QueryKit supports arithmetic expressions in filters, allowing you to perform calculations directly within your queries. This enables powerful filtering capabilities based on computed values.
// Addition: Find records where Age + Rating is greater than 50
var input = "(Age + Rating) > 50";
// Subtraction: Find records where Age - Rating is positive
var input = "(Age - Rating) > 0";
// Multiplication: Find records where Price * Quantity exceeds 1000
var input = "(Price * Quantity) > 1000";
// Division: Find records where Total / Count is less than 100
var input = "(Total / Count) < 100";
// Modulo: Find records where ID is even
var input = "(Id % 2) == 0";Arithmetic expressions follow standard mathematical operator precedence:
// Multiplication and division before addition and subtraction
var input = "(Price + Tax * Rate) > 100"; // Tax * Rate is calculated first
// Use parentheses to override precedence
var input = "((Price + Tax) * Rate) > 100"; // Addition happens firstYou can combine entity properties with literal numeric values:
// Property with literal
var input = "(Age - 18) >= 0"; // Age minus 18
// Multiple properties with literals
var input = "(Price * 1.1 + ShippingCost) <= Budget";Arithmetic expressions can be combined with logical operators and used in complex scenarios:
// Arithmetic with logical operators
var input = """(Price - Cost) > 300 && Category == "Electronics" """;
// Multiple arithmetic comparisons
var input = "(Score1 + Score2) > 150 && (Score1 - Score2) < 20";
// Nested arithmetic expressions
var input = "((Revenue - Expenses) / Revenue) > 0.1";int, decimal, double, float, long, short, byte and their nullable variants// Calculate profit margin and filter
var profitableItems = _dbContext.Products
.ApplyQueryKitFilter("((Price - Cost) / Price) > 0.2")
.ToList();
// Find orders with high shipping ratio
var expensiveShipping = _dbContext.Orders
.ApplyQueryKitFilter("(ShippingCost / TotalAmount) > 0.15")
.ToList();
// Complex business logic in one filter
var qualifiedCustomers = _dbContext.Customers
.ApplyQueryKitFilter("""
(TotalPurchases / NumberOfOrders) > 500 &&
((LastOrderDate - FirstOrderDate) / 365) >= 2
""")
.ToList();You can also filter on queryable projections like so:
var input = $"""info @=* "{fakeAuthorOne.Name}" """;
var config = new QueryKitConfiguration(config =>
{
config.Property<RecipeDto>(x => x.AuthorInfo).HasQueryName("info");
});
var queryableRecipe = testingServiceScope.DbContext().Recipes
.Include(x => x.Author)
.Select(x => new RecipeDto
{
Id = x.Id,
Title = x.Title,
AuthorName = x.Author.Name,
AuthorInfo = x.Author.Name + " - " + x.Author.InternalIdentifier
});
var appliedQueryable = queryableRecipe.ApplyQueryKitFilter(input, config);
var recipes = await appliedQueryable.ToListAsync();You can also filter into collections with QueryKit by using most of the normal operators. For example, if I wanted to filter for recipes that only have an ingredient named salt, I could do something like this:
var input = """"Ingredients.Name == "salt" """";By default, QueryKit will use Any under the hood when building this filter, but if you want to use All, you just need to prefix the operator with a %:
var input = """"Ingredients.Stock %>= 1"""";Nested collections can also be filtered:
var input = $"""preparations == "{preparationOne.Text}" """;
var config = new QueryKitConfiguration(settings =>
{
settings.Property<Recipe>(x => x.Ingredients
.SelectMany(y => y.Preparations)
.Select(y => y.Text))
.HasQueryName("preparations");
});
// Act
var queryableRecipes = testingServiceScope.DbContext().Recipes;
var appliedQueryable = queryableRecipes.ApplyQueryKitFilter(input, config);
var recipes = await appliedQueryable.ToListAsync();If you want to filter a primitve collection like List<string> you can use the Has or DoesNotHave operator (can be case insensitive with the appended *):
var input = """Tags ^$ "winner" """;
// or
var input = """Tags !^$ "winner" """;If you want to filter on the count of a collection, you can prefix some of the operators with a #. For example, if i wanted to get all recipes that have more than 0 ingredients:
var input = """"Ingredients #>= 0"""";You can filter enums with their respective integer value:
var input = "BirthMonth == 1";
public enum BirthMonthEnum
{
January = 1,
February = 2,
//...
}Filtering is set up to create an expression using the property names you have on your entity, but you can pass in a config to customize things a bit when needed.
HasQueryName() to create a custom alias for a property. For exmaple, we can make FirstName aliased to first.PreventFilter() to prevent filtering on a given propertyvar input = $"""first == "Jane" || Age > 10""";
var config = new QueryKitConfiguration(config =>
{
config.Property<SpecialPerson>(x => x.FirstName)
.HasQueryName("first");
config.Property<SpecialPerson>(x => x.Age)
.PreventFilter();
});You can also expose custom derived properties for consumption. Just be sure that Linq can handle them in a db query if you're using it that way.
var config = new QueryKitConfiguration(config =>
{
config.DerivedProperty<Person>(p => p.FirstName + " " + p.LastName).HasQueryName("fullname");
config.DerivedProperty<Person>(p => p.Age >= 18 && p.FirstName == "John").HasQueryName("adult_johns");
});
var input = $"""(fullname @=* "John Doe") && age >= 18""";
// or
var input = $"""adult_johns == true""";For more complex business logic that can't be expressed as simple derived properties, you can define custom operations. These allow you to encapsulate sophisticated filtering logic that can access related data, perform calculations, or implement domain-specific rules.
var config = new QueryKitConfiguration(config =>
{
// Define a custom operation that checks if a book has sold more than X units in the last 10 days
config.CustomOperation<Book>((x, op, value) =>
x.Orders.Where(y => y.OrderDate > DateTime.UtcNow.AddDays(-10))
.Sum(o => o.Quantity) > (int)value)
.HasQueryName("SoldUnitsMoreThan10Days");
// Custom operation for VIP customer detection
config.CustomOperation<Customer>((x, op, value) =>
(bool)value ?
(x.TotalPurchases > 10000 && x.AccountAge > 365 && x.FirstName.Contains("VIP")) :
!(x.TotalPurchases > 10000 && x.AccountAge > 365 && x.FirstName.Contains("VIP")))
.HasQueryName("isVipCustomer");
// Custom operation with date parameter handling
config.CustomOperation<Order>((x, op, value) =>
x.OrderDate > (DateTime)value)
.HasQueryName("isAfterDate");
});
// Usage examples:
var input = """SoldUnitsMoreThan10Days > 100"""; // Books that sold more than 100 units
var input = """isVipCustomer == true"""; // VIP customers only
var input = """isAfterDate == "2023-06-15T00:00:00Z" """; // Orders after specific dateCustom Operation Features:
x.Orders, x.Items)Common Use Cases:
Parameter Type Conversion:
Custom operations automatically handle common data types:
// Boolean parameters
var input = """isEligible == true"""; // Converts "true" to bool
// Numeric parameters
var input = """totalScore > 85.5"""; // Converts "85.5" to decimal/double
var input = """itemCount >= 10"""; // Converts "10" to int
// Date parameters
var input = """lastLoginAfter == "2023-12-01T00:00:00Z" """; // Converts to DateTime
// String parameters (with quotes)
var input = """categoryMatches == "electronics" """; // Keeps as stringCustom operations provide a powerful way to extend QueryKit's filtering capabilities while maintaining type safety and Entity Framework compatibility.
You can also add custom comparison operators to your config if you'd like:
var config = new QueryKitConfiguration(config =>
{
config.EqualsOperator = "@@$";
config.CaseInsensitiveAppendix = "$";
config.AndOperator = "and";
});If you want to use it globally, you can make a base implementation like this:
public class CustomQueryKitConfiguration : QueryKitConfiguration
{
public CustomQueryKitConfiguration(Action<QueryKitSettings>? configureSettings = null)
: base(settings =>
{
settings.EqualsOperator = "eq";
settings.NotEqualsOperator = "neq";
settings.GreaterThanOperator = "gt";
settings.GreaterThanOrEqualOperator = "gte";
settings.LessThanOperator = "lt";
settings.LessThanOrEqualOperator = "lte";
settings.ContainsOperator = "ct";
settings.StartsWithOperator = "sw";
settings.EndsWithOperator = "ew";
settings.NotContainsOperator = "nct";
settings.NotStartsWithOperator = "nsw";
settings.NotEndsWithOperator = "new";
settings.AndOperator = "and";
settings.OrOperator = "or";
settings.CaseInsensitiveAppendix = "i";
configureSettings?.Invoke(settings);
})
{
}
}
// ---
var input = """Title eq$ "Pancakes" and Rating gt 10""";
var config = new CustomQueryKitConfiguration();
var filterExpression = FilterParser.ParseFilter<Recipe>(input, config);Note Spaces must be used around the comparison operator when using custom values.
Title @@$ "titilating"✅Title@@$"titilating"❌
By default, QueryKit will throw an error if it doesn't recognize a property name, If you want to loosen the reigns here a bit, you can set AllowUnknownProperties to true in your config. When active, unknown properties will be ignored in the expression resolution.
var config = new QueryKitConfiguration(config =>
{
config.AllowUnknownProperties = true;
});
var filterExpression = FilterParser.ParseFilter<Recipe>(input, config);Say we have a nested object like this:
public class SpecialPerson
{
public Guid Id { get; set; } = Guid.NewGuid();
public EmailAddress Email { get; set; }
}
public class EmailAddress : ValueObject
{
public EmailAddress(string? value)
{
Value = value;
}
public string? Value { get; private set; }
}To actually use the nested properties, you can do something like this:
var input = $"""Email.Value == "{value}" """;
// or with an alias...
var input = $"""email == "hello@gmail.com" """;
var config = new QueryKitConfiguration(config =>
{
config.Property<SpecialPerson>(x => x.Email.Value).HasQueryName("email");
});Note, with EF core, your config might look like this:
public sealed class PersonConfiguration : IEntityTypeConfiguration<SpecialPerson>
{
public void Configure(EntityTypeBuilder<SpecialPerson> builder)
{
builder.HasKey(x => x.Id);
// Option 1 (as of .NET 8) - ComplexProperty
builder.ComplexProperty(x => x.Email,
x => x.Property(y => y.Value)
.HasColumnName("email"));
// Option 2 - HasConversion (see HasConversion support below)
builder.Property(x => x.Email)
.HasConversion(x => x.Value, x => new EmailAddress(x))
.HasColumnName("email");
// Option 3 - OwnsOne
builder.OwnsOne(x => x.Email, opts =>
{
opts.Property(x => x.Value).HasColumnName("email");
}).Navigation(x => x.Email)
.IsRequired();
}
}For properties configured with EF Core's HasConversion, QueryKit provides special support that allows you to filter against the property directly without needing to access nested values. Use the HasConversion<TTarget>() configuration method:
// EF configuration with HasConversion
builder.Property(x => x.Email)
.HasConversion(x => x.Value, x => new EmailAddress(x))
.HasColumnName("email");
// QueryKit configuration for HasConversion properties
var config = new QueryKitConfiguration(config =>
{
config.Property<SpecialPerson>(x => x.Email)
.HasQueryName("email")
.HasConversion<string>(); // Specify the target type used in HasConversion
});
// Now you can filter directly against the property:
var input = """email == "hello@gmail.com" """;
var people = _dbContext.People
.ApplyQueryKitFilter(input, config)
.ToList();This allows you to use Email == "value" syntax instead of Email.Value == "value" when the property is configured with HasConversion in EF Core. The HasConversion<TTarget>() method tells QueryKit what the conversion target type is so it can handle the type conversion properly.
Sorting is a more simplistic flow. It's just an input with a comma delimited list of properties to sort by.
asc or desc to designate if you want it to be ascending or descending. If neither is used, QueryKit will assume asc- to designate it as descSo all of these are valid:
var input = "Title";
var input = "Title, Age desc";
var input = "Title desc, Age desc";
var input = "Title, Age";
var input = "Title asc, -Age";
var input = "Title, -Age";Sorting is set up to create an expression using the property names you have on your entity, but you can pass in a config to customize things a bit when needed.
HasQueryName() to create a custom alias for a property. For exmaple, we can make FirstName aliased to first.PreventSort() to prevent filtering on a given propertyvar input = $"""Age desc, first"";
var config = new QueryKitConfiguration(config =>
{
config.Property<SpecialPerson>(x => x.FirstName)
.HasQueryName("first")
.PreventSort();
});If you want to apply filtering and sorting in one fell swoop, you can do something like this:
var config = new QueryKitConfiguration(config =>
{
config.Property<Person>(x => x.FirstName).HasQueryName("first");
});
var people = _dbContext.People
.ApplyQueryKit(new QueryKitData()
{
Filters = """first == "Jane" && Age > 10""",
SortOrder = "first, Age desc",
Configuration = config
})
.ToList();If you want to capture errors to easily throw a 400, you can add error handling around these exceptions:
QueryKitException is the base class for all of the exceptions listed below. This can be caught to catch
any exception thrown by QueryKit.ParsingException will be thrown when there is an invalid operator or bad syntax is used (e.g. not using double quotes around a string or guid).UnknownFilterPropertyException will be thrown if a property is not recognized during filteringSortParsingException will be thrown if a property or operation is not recognized during sortingQueryKitDbContextTypeException will be thrown when trying to use a DbContext specific workflow without passing that context (e.g. SoundEx)SoundsLikeNotImplementedException will be thrown when trying to use soundex on a DbContext that doesn't have it implemented.QueryKitParsingException is a more generic error that will include specific details on a more granular error in the parsing pipeline.The Sounds Like and Does Not Sound Like operators require a soundex configuration on any DbContext that contain your DbSet being filtered on. Something like the below should work. The SoundsLike method does not need to implement anything and is just used as a pointer to the db method.
public class ExampleDbContext : DbContext
{
public ExampleDbContext(DbContextOptions<TestingDbContext> options)
: base(options)
{
}
[DbFunction (Name = "SOUNDEX", IsBuiltIn = true)]
public static string SoundsLike(string query) => throw new NotImplementedException();
public DbSet<People> MyPeople { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
base.OnModelCreating(modelBuilder);
modelBuilder.HasPostgresExtension("fuzzystrmatch");
}
}⭐️ Note that with Postgres, something like
modelBuilder.HasPostgresExtension("fuzzystrmatch");will need to be added like the example along with a migration for adding the extension.
You can even use this on a normal IQueryable like this:
var waffleRecipes = _dbContext.MyPeople
.Where(x => ExampleDbContext.SoundsLike(x.LastName) == ExampleDbContext.SoundsLike("devito"))
.ToList();Once your DbContext is configured to allow soundex, you'll need to provide that DbContext type in your QueryKit config. This is because, as of now, there is no reliable way to get the DbContext from an IQueryable.
var input = $"""LastName ~~ "devito" """;
// Act
var queryablePeople = testingServiceScope.DbContext().People;
var appliedQueryable = queryablePeople.ApplyQueryKitFilter(input, new QueryKitConfiguration(o =>
{
o.DbContextType = typeof(TestingDbContext);
}));
var people = await appliedQueryable.ToListAsync();