Lift Framework example source code file (RestHelper.scala)
The Lift Framework RestHelper.scala source code
/*
* Copyright 2010-2011 WorldWide Conferencing, LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.liftweb
package http
package rest
import net.liftweb._
import json._
import common._
import util._
import scala.xml.{Elem, Node, Text}
/**
* Mix this trait into a class to provide a list of REST helper methods
*/
trait RestHelper extends LiftRules.DispatchPF {
import JsonAST._
/**
* Will the request accept a JSON response? Yes if
* the Accept header contains "text/json", "application/json" or
* the Accept header is missing or contains "star/star" and the
* suffix is "json". Override this method to provide your
* own logic. If there's no suffix, no accepts (or it's "star/star")
* then look to either the Content-Type header or the defaultGetAsJson
* flag
*/
protected def jsonResponse_?(in: Req): Boolean = {
(in.acceptsJson_? && !in.acceptsStarStar) ||
((in.weightedAccept.isEmpty ||
in.acceptsStarStar) &&
(in.path.suffix.equalsIgnoreCase("json") ||
in.json_? ||
(in.path.suffix.length == 0 && defaultGetAsJson))) ||
suplimentalJsonResponse_?(in)
}
/**
* If the headers and the suffix say nothing about the
* response type, should we default to JSON. By default,
* yes, override to change the behavior.
*/
protected def defaultGetAsJson: Boolean = true
/**
* If the headers and the suffix say nothing about the
* response type, should we default to XML. By default,
* no, override to change the behavior.
*/
protected def defaultGetAsXml: Boolean = false
/**
* Take any value and convert it into a JValue. Full box if
* it works, empty if it does
*/
protected def anyToJValue(in: Any): Box[JValue] = Helpers.tryo{
implicit def formats = DefaultFormats
Extraction.decompose(in)
}
/**
* If there are additional custom rules (e.g., looking at query parameters)
* you can override this method which is consulted if the other rules
* in jsonResponse_? fail
*/
protected def suplimentalJsonResponse_?(in: Req): Boolean = false
/**
* Will the request accept an XML response? Yes if
* the Accept header contains "application/xml" or "text/xml" or
* the Accept header is missing or contains "star/star" and the
* suffix is "xml". Override this method to provide your
* own logic. If there's no suffix, no accepts (or it's "star/star")
* then look to either the Content-Type header or the defaultGetAsXml
* flag.
*/
protected def xmlResponse_?(in: Req): Boolean = {
(in.acceptsXml_? && !in.acceptsStarStar) ||
((in.weightedAccept.isEmpty ||
in.acceptsStarStar) &&
(in.path.suffix.equalsIgnoreCase("xml") ||
in.xml_? ||
(in.path.suffix.length == 0 && defaultGetAsXml))) ||
suplimentalXmlResponse_?(in)
}
/**
* If there are additional custom rules (e.g., looking at query parameters)
* you can override this method which is consulted if the other rules
* in xmlResponse_? fail
*/
protected def suplimentalXmlResponse_?(in: Req): Boolean = false
/**
* A trait that defines the TestReq extractor. Is
* the request something that expects JSON, XML in the response.
* Subclass this trait to change the behavior
*/
protected trait TestReq {
/**
* Test to see if the request is expecting JSON, XML in the response.
* The path and a Tuple2 representing RequestType and the Req
* instance are extracted.
*/
def unapply(r: Req): Option[(List[String], (RequestType, Req))] =
if (testResponse_?(r))
Some(r.path.partPath -> (r.requestType -> r)) else None
def testResponse_?(r: Req): Boolean
}
protected trait XmlTest {
def testResponse_?(r: Req): Boolean = xmlResponse_?(r)
}
protected trait JsonTest {
def testResponse_?(r: Req): Boolean = jsonResponse_?(r)
}
/**
* The stable identifier for JsonReq. You can use it
* as an extractor.
*/
protected lazy val JsonReq = new TestReq with JsonTest
/**
* The stable identifier for XmlReq. You can use it
* as an extractor.
*/
protected lazy val XmlReq = new TestReq with XmlTest
/**
* A trait that defines the TestGet extractor. Is
* the request a GET and something that expects JSON or XML in the response.
* Subclass this trait to change the behavior
*/
protected trait TestGet {
/**
* Test to see if the request is a GET and expecting JSON in the response.
* The path and the Req instance are extracted.
*/
def unapply(r: Req): Option[(List[String], Req)] =
if (r.get_? && testResponse_?(r))
Some(r.path.partPath -> r) else None
def testResponse_?(r: Req): Boolean
}
/**
* The stable identifier for JsonGet. You can use it
* as an extractor.
*/
protected lazy val JsonGet = new TestGet with JsonTest
/**
* The stable identifier for XmlGet. You can use it
* as an extractor.
*/
protected lazy val XmlGet = new TestGet with XmlTest
/**
* A trait that defines the TestDelete extractor. Is
* the request a DELETE and something that expects
* JSON or XML in the response.
* Subclass this trait to change the behavior
*/
protected trait TestDelete {
/**
* Test to see if the request is a DELETE and
* expecting JSON or XML in the response.
* The path and the Req instance are extracted.
*/
def unapply(r: Req): Option[(List[String], Req)] =
if (r.requestType.delete_? && testResponse_?(r))
Some(r.path.partPath -> r) else None
def testResponse_?(r: Req): Boolean
}
/**
* The stable identifier for JsonDelete. You can use it
* as an extractor.
*/
protected lazy val JsonDelete = new TestDelete with JsonTest
/**
* The stable identifier for XmlDelete. You can use it
* as an extractor.
*/
protected lazy val XmlDelete = new TestDelete with XmlTest
/**
* A trait that defines the TestPost extractor. Is
* the request a POST, has JSON or XML data in the post body
* and something that expects JSON or XML in the response.
* Subclass this trait to change the behavior
*/
protected trait TestPost[T] {
/**
* Test to see if the request is a POST, has JSON data in the
* body and expecting JSON in the response.
* The path, JSON Data and the Req instance are extracted.
*/
def unapply(r: Req): Option[(List[String], (T, Req))] =
if (r.post_? && testResponse_?(r))
body(r).toOption.map(t => (r.path.partPath -> (t -> r)))
else None
def testResponse_?(r: Req): Boolean
def body(r: Req): Box[T]
}
/**
* a trait that extracts the JSON body from a request It is
* composed with a TestXXX to get the correct thing for the extractor
*/
protected trait JsonBody {
def body(r: Req): Box[JValue] = r.json
}
/**
* a trait that extracts the XML body from a request It is
* composed with a TestXXX to get the correct thing for the extractor
*/
protected trait XmlBody {
def body(r: Req): Box[Elem] = r.xml
}
/**
* An extractor that tests the request to see if it's a GET and
* if it is, the path and the request are extracted. It can
* be used as:<br/>
* <pre>case "api" :: id :: _ Get req => ...* or<br/> * <pre>case Get("api" :: id :: _, req) => ... * */ protected object Get { def unapply(r: Req): Option[(List[String], Req)] = if (r.get_?) Some(r.path.partPath -> r) else None } /** * An extractor that tests the request to see if it's a POST and * if it is, the path and the request are extracted. It can * be used as:<br/> * <pre>case "api" :: id :: _ Post req => ... * or<br/> * <pre>case Post("api" :: id :: _, req) => ... */ protected object Post { def unapply(r: Req): Option[(List[String], Req)] = if (r.post_?) Some(r.path.partPath -> r) else None } /** * An extractor that tests the request to see if it's a PUT and * if it is, the path and the request are extracted. It can * be used as:<br/> * <pre>case "api" :: id :: _ Put req => ... * or<br/> * <pre>case Put("api" :: id :: _, req) => ... */ protected object Put { def unapply(r: Req): Option[(List[String], Req)] = if (r.put_?) Some(r.path.partPath -> r) else None } /** * An extractor that tests the request to see if it's a DELETE and * if it is, the path and the request are extracted. It can * be used as:<br/> * <pre>case "api" :: id :: _ Delete req => ... * or<br/> * <pre>case Delete("api" :: id :: _, req) => ... */ protected object Delete { def unapply(r: Req): Option[(List[String], Req)] = if (r.requestType.delete_?) Some(r.path.partPath -> r) else None } /** * A function that chooses JSON or XML based on the request.. * Use with serveType */ implicit def jxSel(req: Req): BoxOrRaw[JsonXmlSelect] = if (jsonResponse_?(req)) JsonSelect else if (xmlResponse_?(req)) XmlSelect else None /** * Serve a given request by determining the request type, computing * the response and then converting the response to the given * type (e.g., JSON or XML).<br/> * @param selection -- a function that determines the response type * based on the Req. * @parama pf -- a PartialFunction that converts the request to a * response type (e.g., a case class that contains the response). * @param cvt -- a function that converts from the response type * to a the appropriate LiftResponse based on the selected response * type. */ protected def serveType[T, SelectType](selection: Req => BoxOrRaw[SelectType]) (pf: PartialFunction[Req, BoxOrRaw[T]]) (implicit cvt: PartialFunction[(SelectType, T, Req), LiftResponse]): Unit = { serve(new PartialFunction[Req, () => Box[LiftResponse]] { def isDefinedAt(r: Req): Boolean = selection(r).isDefined && pf.isDefinedAt(r) def apply(r: Req): () => Box[LiftResponse] = () => { pf(r).box match { case Full(resp) => val selType = selection(r).open_! // Full because pass isDefinedAt if (cvt.isDefinedAt((selType, resp, r))) Full(cvt((selType, resp, r))) else emptyToResp(ParamFailure("Unabled to convert the message", Empty, Empty, 500)) case e: EmptyBox => emptyToResp(e) } } } ) } /** * Serve a request returning either JSON or XML. * * @parama pf -- a Partial Function that converts the request into * an intermediate response. * @param cvt -- convert the intermediate response to a LiftResponse * based on the request being for XML or JSON. If T is JsonXmlAble, * there are built-in converters. Further, you can return auto(thing) * and that will invoke built-in converters as well. The built-in * converters use Lift JSON's Extraction.decompose to convert the object * into JSON and then Xml.toXml() to convert to XML. */ protected def serveJx[T](pf: PartialFunction[Req, BoxOrRaw[T]]) (implicit cvt: JxCvtPF[T]): Unit = serveType(jxSel)(pf)(cvt) protected type JxCvtPF[T] = PartialFunction[(JsonXmlSelect, T, Req), LiftResponse] /** * Serve a request returning either JSON or XML. * * @parama pf -- a Partial Function that converts the request into * Any (note that the response must be convertable into * JSON vis Lift JSON Extraction.decompose */ protected def serveJxa(pf: PartialFunction[Req, BoxOrRaw[Any]]): Unit = serveType(jxSel)(pf)(new PartialFunction[(JsonXmlSelect, Any, Req), LiftResponse] { def isDefinedAt(p: (JsonXmlSelect, Any, Req)) = convertAutoJsonXmlAble.isDefinedAt((p._1, AutoJsonXmlAble(p._2), p._3)) def apply(p: (JsonXmlSelect, Any, Req)) = convertAutoJsonXmlAble.apply((p._1, AutoJsonXmlAble(p._2), p._3)) }) /** * Return the implicit Formats instance for JSON conversion */ protected implicit def formats: Formats = net.liftweb.json.DefaultFormats /** * The default way to convert a JsonXmlAble into JSON or XML */ protected implicit lazy val convertJsonXmlAble: PartialFunction[(JsonXmlSelect, JsonXmlAble, Req), LiftResponse] = { case (JsonSelect, obj, _) => Extraction.decompose(obj) case (XmlSelect, obj, _) => Xml.toXml(Extraction.decompose(obj)).toList match { case x :: _ => x case _ => Text("") } } /** * The class that wraps anything for auto conversion to JSON or XML */ protected final case class AutoJsonXmlAble(obj: Any) /** * wrap anything for autoconversion to JSON or XML */ protected def auto(in: Any): Box[AutoJsonXmlAble] = Full(new AutoJsonXmlAble(in)) /** * Wrap a Box of anything for autoconversion to JSON or XML */ protected def auto(in: Box[Any]): Box[AutoJsonXmlAble] = in.map(obj => new AutoJsonXmlAble(obj)) /** * An implicit conversion that converts AutoJsonXmlAble into * JSON or XML */ protected implicit lazy val convertAutoJsonXmlAble: PartialFunction[(JsonXmlSelect, AutoJsonXmlAble, Req), LiftResponse] = { case (JsonSelect, AutoJsonXmlAble(obj), _) => Extraction.decompose(obj) case (XmlSelect, AutoJsonXmlAble(obj), _) => Xml.toXml(Extraction.decompose(obj)).toList match { case x :: _ => x case _ => Text("") } } /** * The stable identifier for JsonPost. You can use it * as an extractor. */ protected lazy val JsonPost = new TestPost[JValue] with JsonTest with JsonBody /** * The stable identifier for XmlPost. You can use it * as an extractor. */ protected lazy val XmlPost = new TestPost[Elem] with XmlTest with XmlBody /** * A trait that defines the TestPut extractor. Is * the request a PUT, has JSON or XML data in the put body * and something that expects JSON or XML in the response. * Subclass this trait to change the behavior */ protected trait TestPut[T] { /** * Test to see if the request is a PUT, has JSON or XML data in the * body and expecting JSON or XML in the response. * The path, Data and the Req instance are extracted. */ def unapply(r: Req): Option[(List[String], (T, Req))] = if (r.put_? && testResponse_?(r)) body(r).toOption.map(b => (r.path.partPath -> (b -> r))) else None def testResponse_?(r: Req): Boolean def body(r: Req): Box[T] } /** * The stable identifier for JsonPut. You can use it * as an extractor. */ protected lazy val JsonPut = new TestPut[JValue] with JsonTest with JsonBody /** * The stable identifier for XmlPut. You can use it * as an extractor. */ protected lazy val XmlPut = new TestPut[Elem] with XmlTest with XmlBody /** * Extract a Pair using the same syntax that you use to make a Pair */ protected object -> { def unapply[A, B](s: (A, B)): Option[(A, B)] = Some(s._1 -> s._2) } @volatile private var _dispatch: List[LiftRules.DispatchPF] = Nil private lazy val nonDevDispatch = _dispatch.reverse private def dispatch: List[LiftRules.DispatchPF] = if (Props.devMode) _dispatch.reverse else nonDevDispatch /** * Is the Rest helper defined for a given request */ def isDefinedAt(in: Req) = dispatch.find(_.isDefinedAt(in)).isDefined /** * Apply the Rest helper */ def apply(in: Req): () => Box[LiftResponse] = dispatch.find(_.isDefinedAt(in)).get.apply(in) /** * Add request handlers */ protected def serve(handler: PartialFunction[Req, () => Box[LiftResponse]]): Unit = _dispatch ::= handler /** * Turn T into the return type expected by DispatchPF as long * as we can convert T to a LiftResponse. */ protected implicit def thingToResp[T](in: T)(implicit c: T => LiftResponse): () => Box[LiftResponse] = () => Full(c(in)) /** * Turn a Box[T] into the return type expected by * DispatchPF. Note that this method will return * messages from Failure() and return codes and messages * from ParamFailure[Int[(msg, _, _, code) */ protected implicit def boxToResp[T](in: Box[T]) (implicit c: T => LiftResponse): () => Box[LiftResponse] = in match { case Full(v) => () => Full(c(v)) case e: EmptyBox => () => emptyToResp(e) } protected def emptyToResp(eb: EmptyBox): Box[LiftResponse] = eb match { case ParamFailure(msg, _, _, code: Int) => Full(InMemoryResponse(msg.getBytes("UTF-8"), ("Content-Type" -> "text/plain; charset=utf-8") :: Nil, Nil, code)) case Failure(msg, _, _) => Full(NotFoundResponse(msg)) case _ => Empty } /** * Turn an Option[T] into the return type expected by * DispatchPF. */ protected implicit def optionToResp[T](in: Option[T]) (implicit c: T => LiftResponse): () => Box[LiftResponse] = in match { case Some(v) => () => Full(c(v)) case _ => () => Empty } /** * Turn a () => Box[T] into the return type expected by * DispatchPF. Note that this method will return * messages from Failure() and return codes and messages * from ParamFailure[Int[(msg, _, _, code) */ protected implicit def boxFuncToResp[T](in: () => Box[T]) (implicit c: T => LiftResponse): () => Box[LiftResponse] = () => { in() match { case ParamFailure(msg, _, _, code: Int) => Full(InMemoryResponse(msg.getBytes("UTF-8"), ("Content-Type" -> "text/plain; charset=utf-8") :: Nil, Nil, code)) case Failure(msg, _, _) => Full(NotFoundResponse(msg)) case Full(v) => Full(c(v)) case _ => Empty } } /** * Turn an Option[T] into the return type expected by * DispatchPF. */ protected implicit def optionFuncToResp[T](in: () => Option[T]) (implicit c: T => LiftResponse): () => Box[LiftResponse] = () => in() match { case Some(v) => Full(c(v)) case _ => Empty } /** * Override this method to create an AppXmlResponse with the * mime type application/xml rather then text/xml */ protected def createXmlResponse(in: scala.xml.Node): LiftResponse = XmlResponse(in) /** * Convert a Node to an XmlResponse */ protected implicit def nodeToResp(in: scala.xml.Node): LiftResponse = createXmlResponse(in) /** * Convert a JValue to a LiftResponse */ implicit def jsonToResp(in: JsonAST.JValue): LiftResponse = JsonResponse(in) /** * Convert a JsExp to a LiftResponse */ implicit def jsExpToResp(in: js.JsExp): LiftResponse = JavaScriptResponse(in.cmd) /** * Convert a JsCmd to a LiftResponse */ implicit def jsCmdToResp(in: js.JsCmd): LiftResponse = JavaScriptResponse(in) /** @return a SuperString with more available methods such as roboSplit or commafy */ protected implicit def listStringToSuper(in: List[String]): SuperListString = new SuperListString(in) /** @return a SuperString with more available methods such as roboSplit or commafy */ protected implicit def stringToSuper(in: String): SuperString = new SuperString(in) /** * Allows you to use >> after a path list * to handle all the cases where you have a prefix * for a series of differ suffixes with the same * path prefix. For example: * <code> * serve("foo" / "bar" >> { * case baz :: Nil Post _ => ... * case Nil Get _ => ... * }) * </code> */ protected implicit def listToServeMagic(in: List[String]): ListServeMagic = new ListServeMagic(in) /** * Take an original piece of JSON (most probably, JObject * and replace all the JFields with those in toMerge */ protected def mergeJson(original: JValue, toMerge: JValue): JValue = { def replace(lst: List[JField], f: JField): List[JField] = f :: lst.filterNot(_.name == f.name) original match { case JObject(fields) => toMerge match { case jf: JField => JObject(replace(fields, jf)) case JObject(otherFields) => JObject(otherFields.foldLeft(fields)(replace(_, _))) case _ => original } case jf: JField => toMerge match { case jfMerge: JField => JObject(replace(List(jf), jfMerge)) case JObject(otherFields) => JObject(otherFields.foldLeft(List(jf))(replace(_, _))) case _ => original } case _ => original // can't merge } } } /** * Do some magic to prefix path patterns with a single List */ final class ListServeMagic(list: List[String]) { val listLen = list.length /** * Used in conjunction with RestHelper.serveJx to * prefix the pattern matched path. For example: * <code> * serveJx[Foo]("foo" / "bar" prefixJx { * case FindBaz(baz) :: Nil Get _ => baz * }) * </code> */ def prefixJx[T](pf: PartialFunction[Req, BoxOrRaw[T]]): PartialFunction[Req, BoxOrRaw[T]] = new PartialFunction[Req, BoxOrRaw[T]] { def isDefinedAt(req: Req): Boolean = req.path.partPath.startsWith(list) && { pf.isDefinedAt(req.withNewPath(req.path.drop(listLen))) } def apply(req: Req): BoxOrRaw[T] = pf.apply(req.withNewPath(req.path.drop(listLen))) } /** * Used in conjunction with RestHelper.serveJx to * prefix the pattern matched path. For example: * <code> * serve("foo" / "bar" prefix { * case FindBaz(baz) :: Nil GetJson _ => baz: JValue * case FindBaz(baz) :: Nil GetXml _ => baz: Node * }) * </code> */ def prefix(pf: PartialFunction[Req, () => Box[LiftResponse]]): PartialFunction[Req, () => Box[LiftResponse]] = new PartialFunction[Req, () => Box[LiftResponse]] { def isDefinedAt(req: Req): Boolean = req.path.partPath.startsWith(list) && { pf.isDefinedAt(req.withNewPath(req.path.drop(listLen))) } def apply(req: Req): () => Box[LiftResponse] = pf.apply(req.withNewPath(req.path.drop(listLen))) } } /** * A trait that can be mixed into an class (probably a case class) * so that the class can be converted automatically into JSON or XML */ trait JsonXmlAble /** * This trait is part of the ADT that allows the choice between */ sealed trait JsonXmlSelect /** * The Type for JSON */ final case object JsonSelect extends JsonXmlSelect /** * The type for XML */ final case object XmlSelect extends JsonXmlSelect Other Lift Framework examples (source code examples)Here is a short list of links related to this Lift Framework RestHelper.scala source code file: |
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