Simplify promise-based handlers using async-await syntax

Author: rubensworks

lib/handlers/delete.js

@@ -2,18 +2,17 @@ module.exports = handler
 
 const debug = require('../debug').handlers
 
-function handler (req, res, next) {
+async function handler (req, res, next) {
   debug('DELETE -- Request on' + req.originalUrl)
 
   const ldp = req.app.locals.ldp
-  ldp.delete(req)
-    .then(() => {
-      debug('DELETE -- Ok.')
-      res.sendStatus(200)
-      next()
-    })
-    .catch(err => {
-      debug('DELETE -- Failed to delete: ' + err)
-      next(err)
-    })
+  try {
+    await ldp.delete(req)
+    debug('DELETE -- Ok.')
+    res.sendStatus(200)
+    next()
+  } catch (err) {
+    debug('DELETE -- Failed to delete: ' + err)
+    next(err)
+  }
 }

lib/handlers/patch/n3-patch-parser.js

@@ -9,34 +9,35 @@ const PATCH_NS = 'http://www.w3.org/ns/solid/terms#'
 const PREFIXES = `PREFIX solid: <${PATCH_NS}>\n`
 
 // Parses the given N3 patch document
-function parsePatchDocument (targetURI, patchURI, patchText) {
+async function parsePatchDocument (targetURI, patchURI, patchText) {
   // Parse the N3 document into triples
-  return new Promise((resolve, reject) => {
-    const patchGraph = $rdf.graph()
+  const patchGraph = $rdf.graph()
+  try {
     $rdf.parse(patchText, patchGraph, patchURI, 'text/n3')
-    resolve(patchGraph)
-  })
-  .catch(err => { throw error(400, `Patch document syntax error: ${err}`) })
+  } catch (err) {
+    throw error(400, `Patch document syntax error: ${err}`)
+  }
 
   // Query the N3 document for insertions and deletions
-  .then(patchGraph => queryForFirstResult(patchGraph, `${PREFIXES}
+  let firstResult;
+  try {
+    firstResult = await queryForFirstResult(patchGraph, `${PREFIXES}
     SELECT ?insert ?delete ?where WHERE {
       ?patch solid:patches <${targetURI}>.
       OPTIONAL { ?patch solid:inserts ?insert. }
       OPTIONAL { ?patch solid:deletes ?delete. }
       OPTIONAL { ?patch solid:where   ?where.  }
     }`)
-    .catch(err => { throw error(400, `No patch for ${targetURI} found.`, err) })
-  )
+  } catch (err) {
+    throw error(400, `No patch for ${targetURI} found.`, err)
+  }
 
   // Return the insertions and deletions as an rdflib patch document
-  .then(result => {
-    const {'?insert': insert, '?delete': deleted, '?where': where} = result
-    if (!insert && !deleted) {
-      throw error(400, 'Patch should at least contain inserts or deletes.')
-    }
-    return {insert, delete: deleted, where}
-  })
+  const {'?insert': insert, '?delete': deleted, '?where': where} = firstResult
+  if (!insert && !deleted) {
+    throw error(400, 'Patch should at least contain inserts or deletes.')
+  }
+  return {insert, delete: deleted, where}
 }
 
 // Queries the store with the given SPARQL query and returns the first result

lib/handlers/patch/sparql-update-parser.js

@@ -6,13 +6,11 @@ const $rdf = require('rdflib')
 const error = require('../../http-error')
 
 // Parses the given SPARQL UPDATE document
-function parsePatchDocument (targetURI, patchURI, patchText) {
-  return new Promise((resolve, reject) => {
-    const baseURI = patchURI.replace(/#.*/, '')
-    try {
-      resolve($rdf.sparqlUpdateParser(patchText, $rdf.graph(), baseURI))
-    } catch (err) {
-      reject(error(400, `Patch document syntax error: ${err}`))
-    }
-  })
+async function parsePatchDocument (targetURI, patchURI, patchText) {
+  const baseURI = patchURI.replace(/#.*/, '')
+  try {
+    return $rdf.sparqlUpdateParser(patchText, $rdf.graph(), baseURI)
+  } catch (err) {
+    throw error(400, `Patch document syntax error: ${err}`)
+  }
 }

lib/handlers/put.js

@@ -2,21 +2,20 @@ module.exports = handler
 
 const debug = require('debug')('solid:put')
 
-function handler (req, res, next) {
+async function handler (req, res, next) {
   const ldp = req.app.locals.ldp
   debug(req.originalUrl)
   res.header('MS-Author-Via', 'SPARQL')
 
-  ldp.put(req, req)
-    .then(() => {
-      debug('succeded putting the file')
+  try {
+    await ldp.put(req, req)
+    debug('succeded putting the file')
 
-      res.sendStatus(201)
-      return next()
-    })
-    .catch(err => {
-      debug('error putting the file:' + err.message)
-      err.message = 'Can\'t write file: ' + err.message
-      return next(err)
-    })
+    res.sendStatus(201)
+    return next()
+  } catch (err) {
+    debug('error putting the file:' + err.message)
+    err.message = 'Can\'t write file: ' + err.message
+    return next(err)
+  }
 }