Load table items dynamically and enable nice formatting of data

Loading items dynamically gives impression of better responsiveness
with big items that cause slow queries.

Using fancy JSON formatter is probably gonna be slower than just
using JSON.stringify() but I've deemed it worthy due to much better
readability and being able to tell types of item values.

Add possibility to go to previous page of results

Author: rchl

lib/backend.js

@@ -335,7 +335,46 @@ exports.createServer = (dynamodb, docClient) => {
   app.get('/tables/:TableName', (req, res, next) => {
     const TableName = req.params.TableName
     req.query = pickBy(req.query)
-    const filters = omit(req.query, ['_hash', 'range', 'startKey', 'pageNum'])
+    const filters = omit(req.query, ['_hash', 'range', 'prevKey', 'startKey', 'pageNum'])
+
+    describeTable({ TableName })
+      .then(description => {
+        const pageNum = req.query.pageNum ? parseInt(req.query.pageNum) : 1
+        const ExpressionAttributeNames = {}
+        const ExpressionAttributeValues = {}
+        const FilterExpressions = []
+
+        for (const key in filters) {
+          const attributeDefinition = description.Table.AttributeDefinitions.find(
+            definition => {
+              return definition.AttributeName === key
+            }
+          )
+          if (attributeDefinition && attributeDefinition.AttributeType === 'N') {
+            req.query[key] = Number(req.query[key])
+          }
+          ExpressionAttributeNames[`#${key}`] = key
+          ExpressionAttributeValues[`:${key}`] = req.query[key]
+
+          FilterExpressions.push(`#${key} = :${key}`)
+        }
+
+        const data = Object.assign({}, description, {
+          query: req.query,
+          omit,
+          filters,
+          pageNum: pageNum,
+          filterQueryString: querystring.stringify(filters),
+        })
+        res.render('scan', data)
+      })
+      .catch(next)
+  })
+
+  app.get('/tables/:TableName/items', (req, res, next) => {
+    const TableName = req.params.TableName
+    req.query = pickBy(req.query)
+    const filters = omit(req.query, ['_hash', 'range', 'prevKey', 'startKey', 'pageNum'])
 
     describeTable({ TableName })
       .then(description => {
@@ -401,12 +440,14 @@ exports.createServer = (dynamodb, docClient) => {
               omit,
               filters,
               pageNum: pageNum,
+              prevKey: encodeURIComponent(req.query.prevKey || ''),
+              startKey: encodeURIComponent(req.query.startKey || ''),
               nextKey: nextKeyParam,
               filterQueryString: querystring.stringify(filters),
               Items,
               UniqueKeys,
             })
-            res.render('scan', data)
+            res.json(data)
           }
         )
       })

public/vendor/json-formatter/LICENSE

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) 2015 Mohsen Azimi
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.