Promisify util#serialize and util#translate

Author: rubensworks

lib/handlers/get.js

@@ -131,16 +131,17 @@ function handler (req, res, next) {
     }
 
     // Translate from the contentType found to the possibleRDFType desired
-    translate(stream, baseUri, contentType, possibleRDFType, function (err, data) {
-      if (err) {
+    translate(stream, baseUri, contentType, possibleRDFType)
+      .then((data) => {
+        debug(req.originalUrl + ' translating ' + contentType + ' -> ' + possibleRDFType)
+        res.setHeader('Content-Type', possibleRDFType)
+        res.send(data)
+        return next()
+      })
+      .catch((err) => {
         debug('error translating: ' + req.originalUrl + ' ' + contentType + ' -> ' + possibleRDFType + ' -- ' + 500 + ' ' + err.message)
         return next(error(500, 'Error translating between RDF formats'))
-      }
-      debug(req.originalUrl + ' translating ' + contentType + ' -> ' + possibleRDFType)
-      res.setHeader('Content-Type', possibleRDFType)
-      res.send(data)
-      return next()
-    })
+      })
   })
 }
 

lib/ldp.js

@@ -165,18 +165,13 @@ class LDP {
       ))
     })
     .catch(() => { throw error(500, "Can't list container") })
-    .then(() => new Promise((resolve, reject) => {
-      // TODO 'text/turtle' is fixed, should be contentType instead
-      // This forces one more translation turtle -> desired
-      serialize(resourceGraph, reqUri, 'text/turtle', function (err, result) {
-        if (err) {
-          debug.handlers('GET -- Error serializing container: ' + err)
-          reject(error(500, "Can't serialize container"))
-        } else {
-          resolve(result)
-        }
-      })
-    }))
+    // TODO 'text/turtle' is fixed, should be contentType instead
+    // This forces one more translation turtle -> desired
+    .then(() => serialize(resourceGraph, reqUri, 'text/turtle')
+      .catch((err) => {
+        debug.handlers('GET -- Error serializing container: ' + err)
+        return Promise.reject(error(500, "Can't serialize container"))
+      }))
     .then(result => callback(null, result), callback)
   }
 
@@ -237,17 +232,17 @@ class LDP {
       let hostname = parsedUri.hostname
       let path = parsedUri.pathname
 
-      serialize(graph, uri, contentType, (error, content) => {
-        if (error) { return reject(error) }
+      serialize(graph, uri, contentType)
+        .then((content) => {
+          let stream = stringToStream(content)
 
-        let stream = stringToStream(content)
+          this.put(hostname, path, stream, (error) => {
+            if (error) { return reject(error) }
 
-        this.put(hostname, path, stream, (error) => {
-          if (error) { return reject(error) }
-
-          resolve(graph)
+            resolve(graph)
+          })
         })
-      })
+        .catch(reject)
     })
   }
 

lib/utils.js

@@ -143,51 +143,50 @@ function hasSuffix (path, suffixes) {
   return false
 }
 
-function serialize (graph, baseUri, contentType, callback) {
-  try {
-    // target, kb, base, contentType, callback
-    $rdf.serialize(null, graph, baseUri, contentType, function (err, result) {
-      if (err) {
-        console.log(err)
-        return callback(err)
-      }
-      if (result === undefined) {
-        return callback(new Error('Error serializing the graph to ' +
-          contentType))
-      }
+function serialize (graph, baseUri, contentType) {
+  return new Promise((resolve, reject) => {
+    try {
+      // target, kb, base, contentType, callback
+      $rdf.serialize(null, graph, baseUri, contentType, function (err, result) {
+        if (err) {
+          return reject(err)
+        }
+        if (result === undefined) {
+          return reject(new Error('Error serializing the graph to ' +
+            contentType))
+        }
 
-      return callback(null, result)
-    })
-  } catch (err) {
-    console.log(err)
-    callback(err)
-  }
+        resolve(result)
+      })
+    } catch (err) {
+      reject(err)
+    }
+  })
 }
 
-function translate (stream, baseUri, from, to, callback) {
-  // Handle Turtle Accept header
-  if (to === 'text/turtle' ||
-    to === 'text/n3' ||
-    to === 'application/turtle' ||
-    to === 'application/n3') {
-    to = 'text/turtle'
-  }
+function translate (stream, baseUri, from, to) {
+  return new Promise((resolve, reject) => {
+    // Handle Turtle Accept header
+    if (to === 'text/turtle' ||
+      to === 'text/n3' ||
+      to === 'application/turtle' ||
+      to === 'application/n3') {
+      to = 'text/turtle'
+    }
 
-  let data = ''
-  stream
-    .on('data', function (chunk) {
-      data += chunk
-    })
-    .on('end', function () {
-      const graph = $rdf.graph()
-      $rdf.parse(data, graph, baseUri, from, function (err) {
-        if (err) return callback(err)
-        serialize(graph, baseUri, to, function (err, data) {
-          if (err) return callback(err)
-          callback(null, data)
+    let data = ''
+    stream
+      .on('data', function (chunk) {
+        data += chunk
+      })
+      .on('end', function () {
+        const graph = $rdf.graph()
+        $rdf.parse(data, graph, baseUri, from, function (err) {
+          if (err) return reject(err)
+          resolve(serialize(graph, baseUri, to))
         })
       })
-    })
+  })
 }
 
 function stringToStream (string) {