From baeb76e91141867ff099b96c2790fcb2f5331dc3 Mon Sep 17 00:00:00 2001
From: Agnes Lin <agneslin.lin@ibm.com>
Date: Mon, 27 Jan 2020 13:25:31 -0500
Subject: [PATCH] allows diff db cols naming conventions 4 discover

---
 lib/datasource.js      | 51 +++++++++++++++++++++++++++++-------------
 package.json           |  1 +
 test/discovery.test.js | 15 ++++++++++++-
 3 files changed, 51 insertions(+), 16 deletions(-)

diff --git a/lib/datasource.js b/lib/datasource.js
index f82a3e5a..1d2fc20a 100644
--- a/lib/datasource.js
+++ b/lib/datasource.js
@@ -28,6 +28,8 @@ const g = require('strong-globalize')();
 const juggler = require('..');
 const deprecated = require('depd')('loopback-datasource-juggler');
 const Transaction = require('loopback-connector').Transaction;
+const pascalCase = require('change-case').pascalCase;
+const camelCase = require('change-case').camelCase;
 
 if (process.env.DEBUG === 'loopback') {
   // For back-compatibility
@@ -1450,17 +1452,22 @@ function capitalize(str) {
   return str.charAt(0).toUpperCase() + ((str.length > 1) ? str.slice(1).toLowerCase() : '');
 }
 
-function fromDBName(dbName, camelCase) {
-  if (!dbName) {
-    return dbName;
+/**
+ * Renames db column names with different naming conventions:
+ * camelCase for property names as it's LB default naming convention for properties,
+ * or keep the name the same if needed.
+ *
+ * @param {*} name name defined in database
+ * @param {*} caseFunction optional. A function to convert the name into different case.
+ */
+function fromDBName(name, caseFunction) {
+  if (!name) {
+    return name;
   }
-  const parts = dbName.split(/-|_/);
-  parts[0] = camelCase ? parts[0].toLowerCase() : capitalize(parts[0]);
-
-  for (let i = 1; i < parts.length; i++) {
-    parts[i] = capitalize(parts[i]);
+  if (typeof caseFunction === 'function') {
+    return caseFunction(name);
   }
-  return parts.join('');
+  return name;
 }
 
 /**
@@ -1567,13 +1574,14 @@ DataSource.prototype.discoverSchemas = function(tableName, options, cb) {
     cb = options;
     options = {};
   }
-
   cb = cb || utils.createPromiseCallback();
 
   const self = this;
   const dbType = this.connector.name;
 
   let nameMapper;
+  const disableCamelCase = !!options.disableCamelCase;
+
   if (options.nameMapper === null) {
     // No mapping
     nameMapper = function(type, name) {
@@ -1586,11 +1594,19 @@ DataSource.prototype.discoverSchemas = function(tableName, options, cb) {
     // Default name mapper
     nameMapper = function mapName(type, name) {
       if (type === 'table' || type === 'model') {
-        return fromDBName(name, false);
+        return fromDBName(name, pascalCase);
       } else if (type == 'fk') {
-        return fromDBName(name + 'Rel', true);
+        if (disableCamelCase) {
+          return fromDBName(name + 'Rel');
+        } else {
+          return fromDBName(name + 'Rel', camelCase);
+        }
       } else {
-        return fromDBName(name, true);
+        if (disableCamelCase) {
+          return fromDBName(name);
+        } else {
+          return fromDBName(name, camelCase);
+        }
       }
     };
   }
@@ -1770,12 +1786,17 @@ DataSource.prototype.discoverSchemasSync = function(modelName, options) {
   if (!columns || columns.length === 0) {
     return [];
   }
+  const disableCamelCase = !!options.disableCamelCase;
 
   const nameMapper = options.nameMapper || function mapName(type, name) {
     if (type === 'table' || type === 'model') {
-      return fromDBName(name, false);
+      return fromDBName(name, pascalCase);
     } else {
-      return fromDBName(name, true);
+      if (disableCamelCase) {
+        return fromDBName(name);
+      } else {
+        return fromDBName(name, camelCase);
+      }
     }
   };
 
diff --git a/package.json b/package.json
index 3e40fdbc..1cd7e710 100644
--- a/package.json
+++ b/package.json
@@ -49,6 +49,7 @@
   },
   "dependencies": {
     "async": "^3.1.0",
+    "change-case": "^4.1.1",
     "debug": "^4.1.0",
     "depd": "^2.0.0",
     "inflection": "^1.6.0",
diff --git a/test/discovery.test.js b/test/discovery.test.js
index 42429170..c84ee839 100644
--- a/test/discovery.test.js
+++ b/test/discovery.test.js
@@ -73,7 +73,7 @@ describe('Memory connector with mocked discovery', function() {
     };
   });
 
-  it('should convert table/column names to camel cases', function(done) {
+  it('should convert table names to pascal cases and column names to camel case', function(done) {
     ds.discoverSchemas('INVENTORY', {}, function(err, schemas) {
       if (err) return done(err);
       schemas.should.have.property('STRONGLOOP.INVENTORY');
@@ -86,6 +86,19 @@ describe('Memory connector with mocked discovery', function() {
     });
   });
 
+  it('should keep the column names the same as database', function(done) {
+    ds.discoverSchemas('INVENTORY', {disableCamelCase: true}, function(err, schemas) {
+      if (err) return done(err);
+      schemas.should.have.property('STRONGLOOP.INVENTORY');
+      const s = schemas['STRONGLOOP.INVENTORY'];
+      s.name.should.be.eql('Inventory');
+      Object.keys(s.properties).should.be.eql(
+        ['PRODUCT_ID', 'LOCATION_ID', 'AVAILABLE', 'TOTAL'],
+      );
+      done();
+    });
+  });
+
   it('should convert table/column names with custom mapper', function(done) {
     ds.discoverSchemas('INVENTORY', {
       nameMapper: function(type, name) {