• Intro
• Quick Start
• Query Request
• Property Types, Operators and Data Providers
  • Supported Property Types
  • Supported Operators
  • Supported Data Providers
  • Nested and Nullable Properties
• Custom Filter Expressions
  • Shorthand Expressions
• Configuring Query Options
  • Excluding Properties
  • Including ONLY Allowed Properties
  • Property Name Mapping
  • Hiding Mapped Properties
  • Override DateTimeKind
  • Specifying BindingFlags for Property Matching
  • Configuring StringComparison per Query
• Override CultureInfo and Exact Parse Format
  • Extended Capabilities for Runtime IQueryables
• Examples
  • Single Filter
  • Multiple Filters with AND operator
  • Multiple Filters with OR operator
  • Multiple Filters with Complex Logic
  • Multiple Filters with NOT operator
  • Filters on Nested and Nullable Properties
  • Search on Multiple Properties
  • Single Sort
  • Multiple Sorts
• License

Intro

MagiQuery provides a unified API for generic filtering and sorting on C# IQueryables (such as EF entities).

The primary motivation for its development is assisting backend developers in creating simple, yet flexible data query endpoints.

With MagiQuery you can cover a wide range of requests - from the simplest queries to the most complex ones - with a single endpoint!

The idea is simple - you write it once, and it should be able to handle any scenario that might come up on the frontend.

Quick Start

1. Add the NuGet package to your project:

   dotnet add package MagiQuery

2. Get a reference to an IQueryable (be it from a DbContext or somewhere else) and use the ApplyQuery extension method like this:

   [Route("Goblins")]
   public class QueryController(TestDbContext context) : ControllerBase
   {
       [HttpPost("Query")]
       [ProducesResponseType<IEnumerable<Goblin>>(StatusCodes.Status200OK)]
       public IActionResult QueryGoblins([FromBody] QueryRequest request)
       {
           var goblinsQuery = context.Goblins.ApplyQuery(request);
           return Ok(goblinsQuery.ToArray());
       }
   }

   ... or simply use the utility extension method GetPagedResponse to return a result with pagination like this:

   [Route("Goblins")]
   public class QueryController(TestDbContext context) : ControllerBase
   {
       [HttpPost("Query")]
       [ProducesResponseType<QueryPagedResponse<Goblin>>(StatusCodes.Status200OK)]
       public IActionResult QueryGoblins([FromBody] QueryPagedRequest request)
           => Ok(context.Goblins.GetPagedResponse(request));
   }

3. Optionally, add a JsonStringEnumConverter to your serialization options, so you can refer to members of the FilterOperator enum by name, rather than by their int equivalents:

   builder.Services
       .AddControllers()
           .AddJsonOptions(
               x => x.JsonSerializerOptions.Converters.Add(new JsonStringEnumConverter()));

   If you prefer using the int equivalents for members of FilterOperator, please consult the table here.

4. Finally, hit the /Goblins/Query POST endpoint with a payload like this one:

   {
     "filters": [
       {
         "property": "Name", // Name of the property in the Goblin class
         "operator": "StartsWith", // The operator to use for filtering
         "value": "Wiz" // The value to filter with
       },
       {
         "property": "DateOfBirth",
         "operator": "GreaterThan",
         "value": "1010-10-01"
       }
     ]
   }

   ... and you will get a Goblin collection that consist only of goblins, whose names start with Wiz, and who were born after October 1st, 1010.

We have provided a testing playground project WebApiExample in this repository, where you can experiment with MagiQuery and get a feel for how it works and what it can do for you.

It is preloaded with test data and uses an in-memory SQLite database. It has a Swagger implementation loaded with several examples of QueryRequest payloads.

Query Request

The QueryRequest class configures the filtering and sorting parameters of a query on a given IQueryable<TItem>. It has two main components:

• Filters - a collection of filters that will be applied to the IQueryable<TItem>. A filter is defined with:

  • the name of a property of the class TItem
  • a string representation of the value you want to filter with on the specified property
  • a comparison operator from the predefined FilterOperator enum

• Sorts - a collection of sort instructions to be applied to IQueryable<TItem>. A sort is defined with:

  • the name of a property of the class TItem
  • an optional boolean value for using descending order. If this property is omitted from the payload, MagiQuery automatically uses ascending order

Additionally, QueryRequest has two optional properties - FilterExpression and OverrideCulture.

MagiQuery also offers a utility class named QueryRequestPaged, which inherits from QueryRequest and has two extra properties for paging support.

The detailed structure of the two classes can be seen here.

Examples of QueryRequest payloads can be seen here.

Property Types, Operators and Data Providers

Supported Property Types

The following property types are supported in MagiQuery:

• string
• char
• sbyte
• short
• ushort
• byte
• int
• uint
• long
• ulong
• float
• double
• decimal
• bool
• Enum
• DateTime
• DateTimeOffset
• DateOnly
• TimeSpan
• TimeOnly

Supported Operators

The following operators are supported in MagiQuery:

Operator Name	Operator int Id	Description
Equals	0	Relevant for all property types, including nullables.
DoesNotEqual	1	Relevant for all property types, including nullables.
GreaterThan	2	Relevant for all property types, except string, char and bool.
GreaterThanOrEqual	3	Relevant for all property types, except string, char and bool.
LessThan	4	Relevant for all property types, except string, char and bool.
LessThanOrEqual	5	Relevant for all property types, except string, char and bool.
StartsWith	6	Works natively for properties of type string. For other types, MagiQuery will attempt to convert the property value to string during the filtering operation.
EndsWith	7	Works natively for properties of type string. For other types, MagiQuery will attempt to convert the property value to string during the filtering operation.
Contains	8	Works natively for properties of type string. For other types, MagiQuery will attempt to convert the property value to string during the filtering operation.
DoesNotContain	9	Works natively for properties of type string. For other types, MagiQuery will attempt to convert the property value to string during the filtering operation.
IsEmpty	10	Applicable only to types string or char. Works exactly as String.IsNullOrEmpty.
IsNotEmpty	11	Applicable only to types string or char. Works as an inverse of String.IsNullOrEmpty.
Regex	12	Supported only with certain providers, see here. Works natively for properties of type string. For other types, MagiQuery will attempt to convert the property value to string during the filtering operation.

Supported Data Providers

Here is a table showing which properties, operators and features of MagiQuery are supported for each provider:

Name	Source	Properties	Operators	Nullables	Supports String Comparison Override?
Microsoft .EntityFrameworkCore .SqlServer	MSSQL	All	All, except Regex	Full	No
Microsoft .EntityFrameworkCore .Sqlite	SQLite	All, except ulong, DateTimeOffset and TimeSpan. Type decimal is not supported for sorting	All	Full	No
Microsoft .EntityFrameworkCore .InMemory	In-Memory DB	All	All	Full	No
Npgsql .EntityFrameworkCore .PostgreSQL	PostgreSQL	All, except DateOnly and TimeOnly	All	Full	No
Pomelo .EntityFrameworkCore .MySql	MySQL, MariaDB	All, except DateOnly and TimeOnly	All	Full	No
MySql .EntityFrameworkCore	MySQL	All, except DateOnly and TimeOnly	All, except StarsWith, EndsWith and Regex	Full	No
MongoDB .EntityFrameworkCore	MongoDB	All. Limited support for string comparisons for TimeSpan and char (stored as numbers by default) and DateTimeOffset	All	Base Level Only	No
Runtime	IEnumerable	All	All	Full	Yes

Nested and Nullable Properties

MagiQuery supports queries on nested properties. You can use the . operator to go down a level and access a property of a property. For example:

Let's say we are querying a collection with a base class named Goblin, which has a property named Contract. We can go deeper into the structure of Contract, and filter based on lower-level properties, like this:

"property": "Contract.Details.SigningTime"

This property name informs MagiQuery to filter the collection based on the value of the property SigningTime, which is a property of Details, which in turn is a property of Contract, which in turn is a property of the main Goblin class.

MagiQuery will automatically add all necessary null checks to the query as it traverses down the structure of the main class to reach the requested filter property.

Explicit null checks in MagiQuery can be performed by simply omitting the "value" property in your filter definition and using an Equals or DoesNotEqual operator:

    //Filters for entries where Contract is null
    {
      "property": "Contract",
      "operator": "Equals"
    }

    //Filters for entries where Contract is NOT null
    {
      "property": "Contract",
      "operator": "DoesNotEqual"
    }

Custom Filter Expressions

The QueryRequest class allows you to define a custom logical expression that determines how the specified filters in the request are actually applied to the target collection.

Each filter defined in the filters collection in a QueryRequest is essentially a boolean condition.

Using logical operators, you can join together these boolean conditions to create a filtering logic that suits your needs.

There are three building blocks you can use to generate these expressions:

1. Filter Index Numbers - since filters is a collection, each individual filter has a unique 0-based indexing number. In your filter expression, you can use this indexing number to refer to a specific filter.

2. Logical Operators - MagiQuery supports three logical operators:

   • && - this is the AND operator
   • || - this is the OR operator
   • ! - this is the NOT operator

3. Regular Brackets - you can use regular brackets () to isolate specific evaluations to ensure they are executed in the intended order

Here is an example of how you can use a custom regular expression:

Let's say we want to filter for goblins that are:

• Born before January 1st, 2000

OR

• Have MagicPower of 4600000000 or less, and an Id that does not contain the digit 2

We can achieve this with the following QueryRequest:

{
  "filters": [
    {
      "operator": "GreaterThan",
      "value": "4600000000",
      "property": "MagicPower"
    },
    {
      "operator": "DoesNotContain",
      "value": "2",
      "property": "Id"
    },
    {
      "operator": "LessThan",
      "value": "2000-01-01",
      "property": "DateOfBirth"
    }
  ],
  "filterExpression": "2 || (!0 && 1)"
}

Let's break down what is happening in the filter expression 2 || (!0 && 1):

• 2 - this is a reference to the third filter in the filters collection (the filter on DateOfBirth)
• || - this is an OR operator which ensures that either 2 or the result of the expression to the right of the || symbol needs to be true to evaluate the whole expression as true
• ( - a bracket is opened, which will allow us to evaluate all expressions within the bracket as a whole
• !0 - here we see a reference to the first filter in the filters collection (the filter on MagicPower). However, we see that the NOT (!) operator is applied to this filter, meaning we are reversing the result of the boolean expression (i.e. we are looking for MagicPower less than or equal to 4600000000, instead of greater than 4600000000)
• && - this in an AND operator binding the result of the !0 evaluation to the successful evaluation of the expression to the right of the && symbol
• 1 - this is a reference to the second filter in the filters collection (the filter on Id). As a result of the preceding && symbol, both this filter and the previous one need to evaluate as true to evaluate the whole expression in the brackets as true
• ) - we are closing the brackets on the expression.

After applying this custom filter expression, the query result will only contain goblins that are either born before January 1st, 2000, OR have ids that do not contain the digit 2 and have 4600000000 magic power or less.

More examples can be seen in the Examples section.

Shorthand Expressions

MagiQuery offers two shorthand expressions for the most common query scenarios:

1. "filterExpression": "&&" - with this expression all filters will be joined together with an AND logical operator. Basically, this expression tells MagiQuery to perform a traditional filter operation. This is the default value of filterExpression.

2. "filterExpression": "||" - with this expression all filters will be joined together with an OR logical operator. This is the equivalent of a traditional search operation (provided each filter uses the Contains filter operator in its definition).

Configuring Query Options

MagiQuery provides granular control over the query build process via the QueryRequestOptions class. You can pass an instance of QueryRequestOptions as an optional parameter to the ApplyQuery and GetPagedResponse extension methods.

Excluding Properties

ExcludedProperties allows you to specify which properties of the TItem base class in IQueryable<TItem> you would like to explicitly exclude from the query.

For example, here is how you can exclude the properties Name and DateOfBirth from a query on class Goblin:

QueryBuildOptions<Goblin> options = new()
{
    ExcludedProperties = x => x
        .SelectProperty(y => y.Name)
        .SelectProperty(y => y.DateOfBirth)
};

If IncludedProperties is defined, it will override ExcludedProperties.

Including ONLY Allowed Properties

IncludedProperties allows you to specify which properties of the TItem base class in IQueryable<TItem> are allowed to be queried.

If IncludedProperties is defined, MagiQuery will throw an error, if filtering or sorting is attempted on a property that has not been defined explicitly in IncludedProperties.

For example, here is how you can force MagiQuery to only allow filtering and sorting on the Goblin class' properties Id, ExperiencePoints and Age:

QueryBuildOptions<Goblin> options = new()
{
    IncludedProperties = x => x
            .SelectProperty(y => y.Id)
            .SelectProperty(y => y.ExperiencePoints)
            .SelectProperty(y => y.Age)
};

When defined, IncludedProperties will override ExcludedProperties.

Property Name Mapping

Via PropertyMapping, you can specify an alias mapping for the properties of the class TItem in IQueryable<TItem>.

This is very useful, if you would like to hide the structure of the base class, or if you just want to add a developer-friendly nickname for a property, which might have a very long name (for example, a nested property which goes several levels below the base class).

Here is an example of a mapping that will add an alias for the nested property Contract.Details.SigningTime, as well as one for the properties DateOfBirth and Id:

QueryBuildOptions<Goblin> options = new()
{
    PropertyMapping = new()
    {
        {"DOB", x=>x.DateOfBirth},
        {"SigningTime", x=>x.Contract.Details.SigningTime},
        {"GoblinId", x=>x.Id}
    }
};

Having provided this mapping, the FE can pass a payload like this:

{
  "filters": [
    {
        "operator": 4,
        "value": "2022-06-15T12:34:56Z",
        "property": "DOB"
    },
    {
        "operator": 11,
        "value": null,
        "property": "GoblinName"
    }
  ],
  "sorts": [
    {
        "descending": true,
        "property": "SigningTime"
    }
  ]
}

... and MagiQuery will correctly traverse the base class to find the correct properties to do filtering and sorting on.

Hiding Mapped Properties

When PropertyMapping has been defined, you can control whether properties with mapped names can be directly accessed by their actual name. This can be done with the boolean flag HideMappedProperties.

When true, a query can only access a property via its alias (if one has been defined). When false, a property can be accessed either by its alias or by its actual name.

HideMappedProperties is true by default.

Override DateTimeKind

The OverrideDateTimeKind property allows you to override the DateTimeKind used for constructing filter constants of DateTime and DateTimeOffset during the query build.

This is especially useful when using PostgreSQL, as your queries may crash if you use a DateTime with DateTimeKind.Unspecified to filter on a column with type timestamptz.

Specifying BindingFlags for Property Matching

PropertyBindingFlags allows you to specify the BindingFlags to be used during the property name parsing phase of the query build. Here you can read more about BindingFlags.

By default, PropertyBindingFlags has the value:

 BindingFlags.IgnoreCase | BindingFlags.Public | BindingFlags.Instance

Please be careful, if you decide to override the default PropertyBindingFlags value, as you may inadvertently expose properties that should not be accessible from outside your application.

Configuring StringComparison per Query

🔴 IMPORTANT

The StringComparisonType option is supported only for queries on collections that have already been fully loaded into memory, i.e. data provider is Runtime.

Unsupported if you are using a remote source like a database.

The StringComparisonType property allows you to specify the StringComparison/StringComparer to be used during filtering and sorting of IQueryables coming from the Runtime data provider. Here are the supported values:

- StringComparison.Ordinal (default)
- StringComparison.OrdinalIgnoreCase
- StringComparison.InvariantCulture
- StringComparison.InvariantCultureIgnoreCase
- StringComparison.CurrentCulture
- StringComparison.CurrentCultureIgnoreCase

Override CultureInfo and Exact Parse Format

MagiQuery also offers the option to provide an override CultureInfo code and an exact parse format to ensure the string value you provide for a filter is parsed correctly by the .Net application.

Here is how you can do this at filter or sort level:

{
  "filters": [
    {
      "property": "DateOfBirth",
      "operator": "GreaterThan",
      "value": "1030 ЮНИ", // Raw Value
      "overrideCulture": "bg-BG", // Specifying culture to be used
      "exactParseFormat": "yyyy MMMM" // Specifying exact parse format for the value
    },
    {
      "property": "Agility",
      "operator": "LessThan",
      "value": "8,0",
      "overrideCulture": "bg-BG"
    }
  ]
}

If you want to override the CultureInfo on a QueryRequest level, you can rewrite the payload above like this:

{
  "filters": [
    {
      "property": "DateOfBirth",
      "operator": "GreaterThan",
      "value": "1030 ЮНИ",
      "exactParseFormat": "yyyy MMMM"
    },
    {
      "property": "Agility",
      "operator": "LessThan",
      "value": "8,0"
    }
  ],
  "overrideCulture": "bg-BG"
}

.. and the CultureInfo code will be used for all filter and sort definitions.

Even if a request-wide CultureInfo override is in effect, you can still override the CultureInfo code at the level of an individual filter or sort.

Extended Capabilities for Runtime IQueryables

If the collection you are querying has already been fully loaded into memory (i.e. you are using the Runtime data provider), the overrideCulture and exactParseFormat properties are also applied to the members of the collection.

This means that you can do the following:

{
  "filters": [
    {
      "property": "DateOfBirth",
      "operator": "Contains",
      "value": "er 1",
      "exactParseFormat": "MMMM yyyy"
    }
  ],
  "overrideCulture": "de-DE"
}

Which will return all entries where the month name ends in "er" and the first digit of the year is "1".

🔴 IMPORTANT You cannot do this directly with a remote data provider like a database.

If you still want the same functionality with a database, you will first need to query the database to load all relevant entities into a collection in the memory, and then cast the collection as an IQueryable, before applying the QueryRequest. Like this:

[Route("Goblins")]
public class QueryController(TestDbContext context) : ControllerBase
{
    [HttpPost("Query")]
    [ProducesResponseType<QueryResponsePaged<Goblin>>(StatusCodes.Status200OK)]
    public IActionResult QueryGoblins([FromBody] QueryRequestPaged request)
    {
        var goblins = context.Goblins.ToArray();
        return Ok(goblins.AsQueryable().GetPagedResponse(request));
    }
}

Note that this approach can be extremely resource-intensive and should be avoided whenever possible.

If you have no other option but to use it, at least try to narrow down the amount of entries you will need to load into memory to minimize the resource drain on each call.

Examples

The following examples are available as query templates in the WebApiExample provided in this repository.

The WebApiExample comes with preloaded test data, stored in an in-memory SQLite database. It has a Swagger implementation with the payloads below listed as examples.

Single Filter

Here is an example of a single Equals filter on a single property:

{
  "filters": [
    {
      "property": "Name",
      "operator": "Equals",
      "value": "Sigurður"
    }
  ]
}

Multiple Filters with AND operator

Here is an example with multiple filters on a single property with an AND operator. In this case, both conditions need to be satisfied for an entry to appear in the query result (&& operator).

{
  "filters": [
    {
      "property": "Name",
      "operator": "StartsWith",
      "value": "B"
    },
    {
      "property": "Name",
      "operator": "Contains",
      "value": "r"
    }
  ]
}

Multiple Filters with OR operator

Here is an example with multiple filters on a single property, joined with an OR operator. In this case only one of the conditions need to be satisfied for an entry to be included in the result (|| operator).

{
  "filters": [
    {
      "property": "Name",
      "operator": "StartsWith",
      "value": "B"
    },
    {
      "property": "Name",
      "operator": "Contains",
      "value": "r"
    }
  ],
  "filterExpression": "||"
}

Multiple Filters with Complex Logic

Here is an advanced scenario in which we not only have multiple filters, but also a complex logic for including entries. Specifically, we would like to get goblins, whose name starts with "B", and are over 30-years-old, OR goblins, who were born before July 11th 1996, and do not have bitter taste.

{
  "filters": [
    {
      "property": "Name",
      "operator": "StartsWith",
      "value": "B"
    },
    {
      "property": "Age",
      "operator": "GreaterThan",
      "value": "30"
    },
    {
      "property": "DateOfBirth",
      "operator": "LessThanOrEqual",
      "value": "1996-07-11 21:42:09.000"
    },
    {
      "property": "Taste",
      "operator": "DoesNotEqual",
      "value": "Bitter"
    }
  ],
  "filterExpression": "(0 && 1) || (2 && 3)"
}

Multiple Filters with NOT operator

In addition to the AND (&&) and OR (||) operators, filter expressions also support the NOT (!) operator. The ! operator allows you to reverse the condition of a filter without changing the filter operator. As you can see in this example, we filter for IsActive=true, but reverse it with ! in the filterExpression.

{
  "filters": [
    {
      "property": "isActive",
      "operator": "Equals",
      "value": "true"
    },
    {
      "property": "Strength",
      "operator": "GreaterThan",
      "value": "5.1"
    }
  ],
  "filterExpression": "!0 && 1"
}

Filters on Nested and Nullable Properties

MagiQuery supports both nested and nullable properites.

Nested properties are separated from their parents with dots.

If you want to do a null evaluation on a property, you just need to specify the operator and omit the filter's value property in your QueryRequest payload.

{
  "filters": [
    {
      "property": "Contract.Details.SigningTime",
      "operator": "GreaterThan",
      "value": "00:15:00"
    },
    {
      "property": "Contract",
      "operator": "DoesNotEqual"
    },
    {
      "property": "Contract.Details.DaysOfEffect",
      "operator": "Equals"
    }
  ]
}

Search on Multiple Properties

Search is actually a variation of filtering. Just specify the properties you want to search on as filters with the Contains operator and use || in the filterExpression.

{
  "filters": [
    {
      "property": "Name",
      "operator": "Contains",
      "value": "ee"
    },
    {
      "property": "FavouriteLetter",
      "operator": "Contains",
      "value": "ee"
    },
    {
      "property": "Taste",
      "operator": "Contains",
      "value": "ee"
    }
  ],
  "filterExpression": "||"
}

Single Sort

Here is an example of how you can sort entries by a property. The default order is ascending, unless specified otherwise with "descending": "true"

{
  "filters": [
    {
      "property": "Name",
      "operator": "Contains",
      "value": "e"
    }
  ],
  "sorts": [
    {
      "property": "FavouriteLetter"
    }
  ]
}

Multiple Sorts

Here is an example of how you can sort entries by multiple properties. In this case, we are first sorting by date of birth in ascending order, and then by intelligence level in descending order.

{
  "filters": [
    {
      "property": "Salary",
      "operator": "GreaterThanOrEqual",
      "value": "54001"
    }
  ],
  "sorts": [
    {
      "property": "DateOfBirth"
    },
    {
      "property": "IntelligenceLevel",
      "descending": true
    }
  ]
}

License

MIT