Change outconverter for isOson formatted columns to return JSON object

Author: sharadraju

doc/src/release_notes.rst

@@ -13,6 +13,16 @@ node-oracledb `v6.4.0 <https://github.com/oracle/node-oracledb/compare/v6.3.0...
 Common Changes
 ++++++++++++++
 
+#)  Add support for fetching BLOB columns which have "IS JSON FORMAT OSON"
+    constraint enabled in the same way as columns of type JSON.
+    In node-oracledb :ref:`Thick mode <enablingthick>` this requires
+    Oracle Client 21c or higher. Applications can get this new fetch behaviour
+    by setting the oracledb property :attr:`oracledb.future.oldJsonColumnAsObj`
+    to `true`. The default value for this property is `false` which retains
+    the existing fetch behaviour.
+    In a future version, the new fetch behaviour will become default and
+    setting this property will no longer be needed.
+
 #)  Added methods :meth:`~Connection.decodeOSON` and
     :meth:`~Connection.encodeOSON` to support fetching and inserting into
     columns which have the check constraint ``IS JSON FORMAT OSON``

lib/impl/resultset.js

@@ -33,6 +33,7 @@ const settings = require('../settings.js');
 const future = require('../future.js');
 const types = require('../types.js');
 const Lob = require('../lob.js');
+const oson = require('./datahandlers/oson.js');
 
 // define implementation class
 class ResultSetImpl {
@@ -105,26 +106,42 @@ class ResultSetImpl {
     let converter;
     const userConverter = metadata.converter;
 
-    // If IsJson is set convert to JSON objects unless
+    // If IsJson or IsOson is set, convert to JSON objects unless
     // user defined output type handler overwrites it.
-    if (future.oldJsonColumnAsObj && metadata.isJson && metadata.dbType !== types.DB_TYPE_JSON
+    if (metadata.dbType !== types.DB_TYPE_JSON && future.oldJsonColumnAsObj
       && userConverter === undefined) {
-      const outConverter = async function(val) {
-        if (!val) {
-          return val;
-        }
+      let outConverter;
+      if (metadata.isOson) {
+        outConverter = async function(val) {
+          if (!val) {
+            return val;
+          }
+          let result = val;
+          if (val instanceof Lob) {
+            result = await val.getData();
+          }
+          const decoder = new oson.OsonDecoder(result);
+          return decoder.decode();
+        };
+        converter = outConverter;
+      } else if (metadata.isJson) {
+        outConverter = async function(val) {
+          if (!val) {
+            return val;
+          }
 
-        let result = val;
-        if (val instanceof Lob) {
-          result = await val.getData();
-        }
-        if (result instanceof Buffer) {
-          result = result.toString();
-        }
-        result = JSON.parse(result);
-        return result;
-      };
-      converter = outConverter;
+          let result = val;
+          if (val instanceof Lob) {
+            result = await val.getData();
+          }
+          if (result instanceof Buffer) {
+            result = result.toString();
+          }
+          result = JSON.parse(result);
+          return result;
+        };
+        converter = outConverter;
+      }
     }
 
     // in thin mode, Oracle NUMBER values are internally fetched as string in

test/dataTypeBlob.js

@@ -167,7 +167,6 @@ describe('41. dataTypeBlob.js', function() {
     const plsql = testsUtil.sqlCreateTable(TABLE, createTable);
 
     before('create table', async function() {
-      oracledb.fetchAsBuffer = [oracledb.BLOB];
       if (testsUtil.getClientVersion() >= 2100000000 &&
         connection.oracleServerVersion >= 2100000000) {
         isRunnable = true;
@@ -177,11 +176,13 @@ describe('41. dataTypeBlob.js', function() {
         this.skip();
       }
 
+      // Allows automatically converting OSON formatted columns to JSON objects.
+      oracledb.future.oldJsonColumnAsObj = true;
       await connection.execute(plsql);
     });
 
     after(async function() {
-      oracledb.fetchAsBuffer = [];
+      oracledb.future.oldJsonColumnAsObj = false;
       await connection.execute(testsUtil.sqlDropTable(TABLE));
     });
 
@@ -203,25 +204,30 @@ describe('41. dataTypeBlob.js', function() {
       values (1, :1, :2) `,
       [byteBuf, byteBuf]);
       result = await connection.execute(`select OSONCOL from ${TABLE}`);
-      let generatedObj = connection.decodeOSON(result.rows[0][0]);
-      assert.deepStrictEqual(expectedObj1, generatedObj);
+      assert.deepStrictEqual(expectedObj1, result.rows[0][0]);
 
       // Generate OSON bytes and insert these bytes and verify with decode.
       const osonBytes = connection.encodeOSON(expectedObj2);
       result = await connection.execute(`insert into ${TABLE}(IntCol, OsonCol, blobCol)
       values (2, :1, :2) `,
       [osonBytes, byteBuf]);
       result = await connection.execute(`select OSONCOL from ${TABLE} where IntCol = 2`);
-      generatedObj = connection.decodeOSON(result.rows[0][0]);
-      assert.deepStrictEqual(expectedObj2, generatedObj);
+      assert.deepStrictEqual(expectedObj2, result.rows[0][0]);
 
       // Verify vector inside OSON image for 23.4 server onwards.
       if (connection.oracleServerVersion >= 2304000000) {
         result = await connection.execute(`insert into ${TABLE}(IntCol, OsonCol, blobCol)
       values (3, :1, :2) `,
         [connection.encodeOSON(expectedObj3), byteBuf]);
         result = await connection.execute(`select OSONCOL from ${TABLE} where IntCol = 3`);
-        generatedObj = connection.decodeOSON(result.rows[0][0]);
+        assert.deepStrictEqual(expectedObj3, result.rows[0][0]);
+
+        // Verify LOB is returned by default (oracledb.future.oldJsonColumnAsObj = false).
+        // We need to explicitly use decodeOSON to convert the LOB data into JSON object.
+        oracledb.future.oldJsonColumnAsObj = false;
+        result = await connection.execute(`select OSONCOL from ${TABLE} where IntCol = 3`);
+        const lob = result.rows[0][0];
+        const generatedObj = connection.decodeOSON(await lob.getData());
         assert.deepStrictEqual(expectedObj3, generatedObj);
       }