Class FormFieldAttribute

Specifies that a parameter of a controller method will receive the value(s) of a field in a HTML form, obtained by deserializing a request body with a content type of application/x-www-form-urlencoded.

The parameter carrying this attribute can be either a simple type or a one-dimension array.

If multiple values are present for the field, a non-array parameter will receive the last specified value, while an array parameter will receive an array of field values converted to the element type of the parameter.

If a single value is present for the field, a non-array parameter will receive the value converted to the type of the parameter, while an array parameter will receive an array of length 1, containing the value converted to the element type of the parameter

If no values are present for the field and the BadRequestIfMissing property is true, a 400 Bad Request response will be sent to the client, with a message specifying the name of the missing field.

If no values are present for the field and the BadRequestIfMissing property is false, a non-array parameter will receive the default value for its type, while an array parameter will receive an array of length 0.

This class cannot be inherited.

Inheritance
Object
FormFieldAttribute
Namespace: EmbedIO.WebApi
Syntax
public sealed class FormFieldAttribute : Attribute, IRequestDataAttribute<WebApiController, string>, INonNullRequestDataAttribute<WebApiController, string[]>, IRequestDataAttribute<WebApiController>

Constructors

FormFieldAttribute()

Initializes a new instance of the FormFieldAttribute class. The name of the form field to extract will be equal to the name of the parameter carrying this attribute.

Declaration
public FormFieldAttribute()

FormFieldAttribute(Boolean)

Initializes a new instance of the FormFieldAttribute class. The name of the form field to extract will be equal to the name of the parameter carrying this attribute.

Declaration
public FormFieldAttribute(bool badRequestIfMissing)
Parameters
Type Name Description
Boolean badRequestIfMissing

If set to true, a 400 Bad Request response will be sent to the client if no values are found for the field; if set to false, a default value will be assumed.

FormFieldAttribute(String)

Initializes a new instance of the FormFieldAttribute class.

Declaration
public FormFieldAttribute(string fieldName)
Parameters
Type Name Description
String fieldName

The name of the form field to extract.

FormFieldAttribute(String, Boolean)

Initializes a new instance of the FormFieldAttribute class.

Declaration
public FormFieldAttribute(string fieldName, bool badRequestIfMissing)
Parameters
Type Name Description
String fieldName

The name of the form field to extract.
Boolean badRequestIfMissing

If set to true, a 400 Bad Request response will be sent to the client if no values are found for the field; if set to false, a default value will be assumed.

Properties

BadRequestIfMissing

Gets or sets a value indicating whether to send a 400 Bad Request response to the client if the submitted form contains no values for the field.

If this property is true and the submitted form contains no values for the field, the 400 Bad Request response sent to the client will contain a reference to the missing field.

If this property is false and the submitted form contains no values for the field, the default value for the parameter (or a zero-length array if the parameter is of an array type) will be passed to the controller method.

Declaration
public bool BadRequestIfMissing { get; }
Property Value
Type Description
Boolean

FieldName

Gets the name of the form field that this attribute will extract, or null if the name of the parameter carrying this attribute is to be used as field name.

Declaration
public string FieldName { get; }
Property Value
Type Description
String

Explicit Interface Implementations

INonNullRequestDataAttribute<WebApiController, String[]>.GetRequestDataAsync(WebApiController, String)

Declaration
Task<string[]> INonNullRequestDataAttribute<WebApiController, string[]>.GetRequestDataAsync(WebApiController controller, string parameterName)
Parameters
Type Name Description
WebApiController controller
String parameterName
Returns
Type Description
Task<String[]>

IRequestDataAttribute<WebApiController, String>.GetRequestDataAsync(WebApiController, String)

Declaration
Task<string> IRequestDataAttribute<WebApiController, string>.GetRequestDataAsync(WebApiController controller, string parameterName)
Parameters
Type Name Description
WebApiController controller
String parameterName
Returns
Type Description
Task<String>

IRequestDataAttribute<WebApiController>.GetRequestDataAsync(WebApiController, Type, String)

Declaration
Task<object> IRequestDataAttribute<WebApiController>.GetRequestDataAsync(WebApiController controller, Type type, string parameterName)
Parameters
Type Name Description
WebApiController controller
Type type
String parameterName
Returns
Type Description
Task<Object>

Implements

See Also

IRequestDataAttribute<TController, TData>
INonNullRequestDataAttribute<TController, TData>

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