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Lift Framework example source code file (RestHelper.scala)

This example Lift Framework source code file (RestHelper.scala) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Lift Framework tags/keywords

boolean, boolean, box, box, boxorraw, full, liftresponse, none, option, partialfunction, partialfunction, req, req, t

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

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