| Safe Haskell | None |
|---|---|
| Language | Haskell2010 |
IHP.ViewPrelude
Synopsis
- module IHP.Prelude
- module IHP.View.TimeAgo
- stringValue :: String -> AttributeValue
- module IHP.View.Form
- module IHP.View.Types
- hsx :: QuasiQuoter
- toHtml :: ToHtml a => a -> Html
- preEscapedToHtml :: ToMarkup a => a -> Html
- preEscapedTextValue :: Text -> AttributeValue
- module IHP.ValidationSupport
- pathTo :: HasPath controller => controller -> Text
- urlTo :: (?context :: context, ConfigProvider context, HasPath action) => action -> Text
- module IHP.ViewSupport
- module IHP.ModelSupport
- module IHP.FrameworkConfig
- (!) :: Attributable h => h -> Attribute -> h
- module Data.Data
- class FromJSON a where
- parseJSON :: Value -> Parser a
- parseJSONList :: Value -> Parser [a]
- omittedField :: Maybe a
- class ToJSON a where
- toJSON :: a -> Value
- toEncoding :: a -> Encoding
- toJSONList :: [a] -> Value
- toEncodingList :: [a] -> Encoding
- omitField :: a -> Bool
- class KeyValue e kv | kv -> e where
- (.=) :: ToJSON v => Key -> v -> kv
- explicitToField :: (v -> e) -> Key -> v -> kv
- module IHP.AutoRefresh.View
- module IHP.View.Classes
- module IHP.FlashMessages.ViewFunctions
- module IHP.Controller.Context
- module IHP.Controller.Layout
- module IHP.Modal.Types
- module IHP.Modal.ViewFunctions
- module IHP.Job.Types
- module IHP.LoginSupport.Helper.View
- module IHP.PageHead.ViewFunctions
- module IHP.Assets.ViewFunctions
- module IHP.Breadcrumb.ViewFunctions
- module IHP.Pagination.ViewFunctions
Documentation
module IHP.Prelude
module IHP.View.TimeAgo
stringValue :: String -> AttributeValue Source #
Create an attribute value from a String.
module IHP.View.Form
module IHP.View.Types
hsx :: QuasiQuoter Source #
preEscapedToHtml :: ToMarkup a => a -> Html Source #
Arguments
| :: Text | The actual value |
| -> AttributeValue | Resulting attribute value |
Render an attribute value from Text without escaping.
module IHP.ValidationSupport
pathTo :: HasPath controller => controller -> Text Source #
Returns the path to a given action
>>>pathTo UsersAction"/Users"
>>>pathTo ShowUserAction { userId = "a32913dd-ef80-4f3e-9a91-7879e17b2ece" }"/ShowUser?userId=a32913dd-ef80-4f3e-9a91-7879e17b2ece"
urlTo :: (?context :: context, ConfigProvider context, HasPath action) => action -> Text Source #
Returns the url to a given action.
Uses the baseUrl configured in Config/Config.hs. When no baseUrl
is configured in development mode, it will automatically detect the
correct baseUrl value.
>>>urlTo UsersAction"http://localhost:8000/Users"
>>>urlTo ShowUserAction { userId = "a32913dd-ef80-4f3e-9a91-7879e17b2ece" }"http://localhost:8000/ShowUser?userId=a32913dd-ef80-4f3e-9a91-7879e17b2ece"
module IHP.ViewSupport
module IHP.ModelSupport
module IHP.FrameworkConfig
(!) :: Attributable h => h -> Attribute -> h Source #
Apply an attribute to an element.
Example:
img ! src "foo.png"
Result:
<img src="foo.png" />
This can be used on nested elements as well.
Example:
p ! style "float: right" $ "Hello!"
Result:
<p style="float: right">Hello!</p>
module Data.Data
class FromJSON a where Source #
A type that can be converted from JSON, with the possibility of failure.
In many cases, you can get the compiler to generate parsing code for you (see below). To begin, let's cover writing an instance by hand.
There are various reasons a conversion could fail. For example, an
Object could be missing a required key, an Array could be of
the wrong size, or a value could be of an incompatible type.
The basic ways to signal a failed conversion are as follows:
failyields a custom error message: it is the recommended way of reporting a failure;empty(ormzero) is uninformative: use it when the error is meant to be caught by some(;<|>)typeMismatchcan be used to report a failure when the encountered value is not of the expected JSON type;unexpectedis an appropriate alternative when more than one type may be expected, or to keep the expected type implicit.
prependFailure (or modifyFailure) add more information to a parser's
error messages.
An example type and instance using typeMismatch and prependFailure:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceFromJSONCoord whereparseJSON(Objectv) = Coord<$>v.:"x"<*>v.:"y" -- We do not expect a non-Objectvalue here. -- We could useemptyto fail, buttypeMismatch-- gives a much more informative error message.parseJSONinvalid =prependFailure"parsing Coord failed, " (typeMismatch"Object" invalid)
For this common case of only being concerned with a single
type of JSON value, the functions withObject, withScientific, etc.
are provided. Their use is to be preferred when possible, since
they are more terse. Using withObject, we can rewrite the above instance
(assuming the same language extension and data type) as:
instanceFromJSONCoord whereparseJSON=withObject"Coord" $ \v -> Coord<$>v.:"x"<*>v.:"y"
Instead of manually writing your FromJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
parseJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericFromJSON instance for your datatype without giving
a definition for parseJSON.
For example, the previous example can be simplified to just:
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance FromJSON Coord
or using the DerivingVia extension
deriving viaGenericallyCoord instanceFromJSONCoord
The default implementation will be equivalent to
parseJSON = ; if you need different
options, you can customize the generic decoding by defining:genericParseJSON defaultOptions
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceFromJSONCoord whereparseJSON=genericParseJSONcustomOptions
Minimal complete definition
Nothing
Methods
parseJSON :: Value -> Parser a Source #
parseJSONList :: Value -> Parser [a] Source #
omittedField :: Maybe a Source #
Default value for optional fields.
Used by ( operator, and Generics and TH deriving
with .:?=)allowOmittedFields = True
Since: aeson-2.2.0.0
Instances
A type that can be converted to JSON.
Instances in general must specify toJSON and should (but don't need
to) specify toEncoding.
An example type and instance:
-- Allow ourselves to writeTextliterals. {-# LANGUAGE OverloadedStrings #-} data Coord = Coord { x :: Double, y :: Double } instanceToJSONCoord wheretoJSON(Coord x y) =object["x".=x, "y".=y]toEncoding(Coord x y) =pairs("x".=x<>"y".=y)
Instead of manually writing your ToJSON instance, there are two options
to do it automatically:
- Data.Aeson.TH provides Template Haskell functions which will derive an instance at compile time. The generated instance is optimized for your type so it will probably be more efficient than the following option.
- The compiler can provide a default generic implementation for
toJSON.
To use the second, simply add a deriving clause to your
datatype and declare a GenericToJSON instance. If you require nothing other than
defaultOptions, it is sufficient to write (and this is the only
alternative where the default toJSON implementation is sufficient):
{-# LANGUAGE DeriveGeneric #-}
import GHC.Generics
data Coord = Coord { x :: Double, y :: Double } deriving Generic
instance ToJSON Coord where
toEncoding = genericToEncoding defaultOptions
or more conveniently using the DerivingVia extension
deriving viaGenericallyCoord instanceToJSONCoord
If on the other hand you wish to customize the generic decoding, you have to implement both methods:
customOptions =defaultOptions{fieldLabelModifier=maptoUpper} instanceToJSONCoord wheretoJSON=genericToJSONcustomOptionstoEncoding=genericToEncodingcustomOptions
Previous versions of this library only had the toJSON method. Adding
toEncoding had two reasons:
toEncodingis more efficient for the common case that the output oftoJSONis directly serialized to aByteString. Further, expressing either method in terms of the other would be non-optimal.- The choice of defaults allows a smooth transition for existing users:
Existing instances that do not define
toEncodingstill compile and have the correct semantics. This is ensured by making the default implementation oftoEncodingusetoJSON. This produces correct results, but since it performs an intermediate conversion to aValue, it will be less efficient than directly emitting anEncoding. (this also means that specifying nothing more thaninstance ToJSON Coordwould be sufficient as a generically decoding instance, but there probably exists no good reason to not specifytoEncodingin new instances.)
Minimal complete definition
Nothing
Methods
Convert a Haskell value to a JSON-friendly intermediate type.
toEncoding :: a -> Encoding Source #
Encode a Haskell value as JSON.
The default implementation of this method creates an
intermediate Value using toJSON. This provides
source-level compatibility for people upgrading from older
versions of this library, but obviously offers no performance
advantage.
To benefit from direct encoding, you must provide an
implementation for this method. The easiest way to do so is by
having your types implement Generic using the DeriveGeneric
extension, and then have GHC generate a method body as follows.
instanceToJSONCoord wheretoEncoding=genericToEncodingdefaultOptions
toJSONList :: [a] -> Value Source #
toEncodingList :: [a] -> Encoding Source #
omitField :: a -> Bool Source #
Defines when it is acceptable to omit a field of this type from a record.
Used by ( operator, and Generics and TH deriving
with .?=)omitNothingFields = True
Since: aeson-2.2.0.0
Instances
class KeyValue e kv | kv -> e where Source #
A key-value pair for encoding a JSON object.
Methods
(.=) :: ToJSON v => Key -> v -> kv infixr 8 Source #
explicitToField :: (v -> e) -> Key -> v -> kv Source #
Since: aeson-2.2.0.0
Instances
| KeyValue Encoding Series | |
| value ~ Value => KeyValue Value (KeyMap value) | Constructs a singleton |
| (key ~ Key, value ~ Value) => KeyValue Value (key, value) | |
module IHP.AutoRefresh.View
module IHP.View.Classes
module IHP.Controller.Context
module IHP.Controller.Layout
module IHP.Modal.Types
module IHP.Modal.ViewFunctions
module IHP.Job.Types
module IHP.LoginSupport.Helper.View
module IHP.PageHead.ViewFunctions
module IHP.Assets.ViewFunctions
module IHP.Breadcrumb.ViewFunctions
module IHP.Pagination.ViewFunctions