(feat): support for "begins_with" operator searches

.gitignore

@@ -2,3 +2,5 @@
 node_modules
 yarn.lock
 .idea/
+.vscode/
+.npmrc

lib/backend.js

@@ -248,7 +248,6 @@ exports.createServer = (dynamodb, docClient) => {
             }
           }
 
-
           if (secondaryIndex.IndexType === 'global') {
             index.ProvisionedThroughput = {
               ReadCapacityUnits: req.body.ReadCapacityUnits,
@@ -400,6 +399,7 @@ exports.createServer = (dynamodb, docClient) => {
             '<=': '<=',
             '>': '>',
             '<': '<',
+            'begins_with': 'begins_with'
           },
           attributeTypes: {
             'S': 'String',
@@ -450,11 +450,30 @@ exports.createServer = (dynamodb, docClient) => {
           if (indexBeingUsed && indexBeingUsed.KeySchema.find(
             (keySchemaItem) => keySchemaItem.AttributeName === key)
           ) {
-            KeyConditionExpression.push(`#key${i} ${filters[key].operator} :key${i}`)
+            const matchedKeySchema = indexBeingUsed.KeySchema.find(
+              (keySchemaItem) => keySchemaItem.AttributeName === key)
+
+            if (matchedKeySchema.KeyType === 'HASH') {
+              KeyConditionExpression.push(
+                `#key${i} ${filters[key].operator} :key${i}`)
+            } else if (matchedKeySchema.KeyType === 'RANGE') {
+              if (filters[key].operator === 'begins_with') {
+                KeyConditionExpression.push(
+                  `${filters[key].operator} ( #key${i} , :key${i})`)
+              } else {
+                KeyConditionExpression.push(
+                  `#key${i} ${filters[key].operator} :key${i}`)
+              }
+            }
           } else {
             ExpressionAttributeNames[`#key${i}`] = key
             ExpressionAttributeValues[`:key${i}`] = filters[key].value
-            FilterExpressions.push(`#key${i} ${filters[key].operator} :key${i}`)
+
+            if (filters[key].operator === 'begins_with') {
+              FilterExpressions.push(`${filters[key].operator} ( #key${i} , :key${i})`)
+            } else {
+              FilterExpressions.push(`#key${i} ${filters[key].operator} :key${i}`)
+            }
           }
           // Increment the unique ID variable
           i = i + 1
@@ -658,6 +677,7 @@ exports.createServer = (dynamodb, docClient) => {
 
   return app
 }
+
 function isAttributeNotAlreadyCreated(attributeDefinitions, attributeName) {
   return !attributeDefinitions
     .find(attributeDefinition => attributeDefinition.AttributeName === attributeName)