Class BindingOptions

request binding options

Inheritance
object
BindingOptions
Inherited Members
Namespace: FastEndpoints
Assembly: FastEndpoints.dll
Syntax
public sealed class BindingOptions

Properties

FailureMessage

a function used to construct the failure message when a supplied value cannot be succesfully bound to a dto property during model binding.

NOTE: this only applies to non-STJ operations. for customizing error messages of STJ binding failures, specify a JsonExceptionTransformer func.

the following arguments are supplied to the function.

Type: the type of the property which failed to bind

string: the name of the property which failed to bind

StringValues: the value that was attempted which resulted in the failure

use these input parameters and construct your own error message string and return it from the function.
Declaration
public Func<Type, string, StringValues, string> FailureMessage { set; }
Property Value
Type Description
Func<Type, string, StringValues, string>

JsonExceptionTransformer

by default, all STJ JsonExceptions thrown during deserialization are automatically caught and transformed using this function. if you'd like to disable this behavior, simply set this property to null or specify a function to construct a FluentValidation.Results.ValidationFailure when STJ throws an exception due to invalid json input.

NOTE: this only applies to STJ based operations. for customizing error messages of non-STJ binding failures, specify a FailureMessage func.

Declaration
public Func<JsonException, ValidationFailure>? JsonExceptionTransformer { set; }
Property Value
Type Description
Func<JsonException, ValidationFailure>

Modifier

an optional action to be run after the endpoint level request binding has occured. it is intended as a way to perform common model binding logic that applies to all endpoints/requests. the action is passed in the following arguments:

object: the request dto instance

Type: the type of the request dto

BinderContext: the request binding context

CancellationToken: a cancellation token

WARNING: be mindful of the performance cost of using reflection to modify the request dto object

Declaration
public Action<object, Type, BinderContext, CancellationToken>? Modifier { set; }
Property Value
Type Description
Action<object, Type, BinderContext, CancellationToken>

Methods

ValueParserFor(Type, Func<object?, ParseResult>)

add a custom value parser function for any given type which the default model binder will use to parse values when model binding request dto properties from query/route/forms/headers/claims. this is an alternative approach to adding a TryParse() function to your types that need model binding support from the abovementioned binding sources. once you register a parser function here for a type, any TryParse() method on the type will not be used for parsing. also, these parser functions do not apply to JSON deserialization done by STJ and can be considered the equivalent to registering a custom converter in STJ when it comes to query/route/forms/headers/claims binding sources.

Declaration
public bool ValueParserFor(Type type, Func<object?, ParseResult> parser)
Parameters
Type Name Description
Type type

the type of the class which this parser function will target
Func<object, ParseResult> parser

a function that takes in a nullable object and returns a ParseResult as the output.

app.UseFastEndpoints(c =>
{
    c.Binding.ValueParserFor(typeof(Guid), MyParsers.GuidParser);
});

public static class MyParsers
{
    public static ParseResult GuidParser(object? input)
    {
        Guid result;
        bool success = Guid.TryParse(input?.ToString(), out result);
        return new(success, result);
    }
}
Returns
Type Description
bool

ValueParserFor<T>(Func<object?, ParseResult>)

add a custom value parser function for any given type which the default model binder will use to parse values when model binding request dto properties from query/route/forms/headers/claims. this is an alternative approach to adding a TryParse() function to your types that need model binding support from the abovementioned binding sources. once you register a parser function here for a type, any TryParse() method on the type will not be used for parsing. also, these parser functions do not apply to JSON deserialization done by STJ and can be considered the equivalent to registering a custom converter in STJ when it comes to query/route/forms/headers/claims binding sources.

Declaration
public bool ValueParserFor<T>(Func<object?, ParseResult> parser)
Parameters
Type Name Description
Func<object, ParseResult> parser

a function that takes in a nullable object and returns a ParseResult as the output.

app.UseFastEndpoints(c =>
{
    c.Binding.ValueParserFor<Guid>(MyParsers.GuidParser);
});

public static class MyParsers
{
    public static ParseResult GuidParser(object? input)
    {
        Guid result;
        bool success = Guid.TryParse(input?.ToString(), out result);
        return new(success, result);
    }
}
Returns
Type Description
bool
Type Parameters
Name Description
T

the type of the class which this parser function will target

ValueParserWhen(Func<PropertyInfo, bool>, Func<object?, Type, ParseResult>)

override value parsers for request dto properties that match a predicate.

WARNING: might lead to weird/untraceable behavior. use at own risk!

Declaration
public void ValueParserWhen(Func<PropertyInfo, bool> propertyMatcher, Func<object?, Type, ParseResult> parser)
Parameters
Type Name Description
Func<PropertyInfo, bool> propertyMatcher

a predicate for qualifying a property
Func<object, Type, ParseResult> parser

the value parser for the matched property type