137 lines
3.5 KiB
JavaScript
137 lines
3.5 KiB
JavaScript
/* Copyright (c) 2015, 2017, Oracle and/or its affiliates. All rights reserved. */
|
|
|
|
/******************************************************************************
|
|
*
|
|
* You may not use the identified files except in compliance with the Apache
|
|
* License, Version 2.0 (the "License.")
|
|
*
|
|
* You may obtain a copy of the License at
|
|
* http://www.apache.org/licenses/LICENSE-2.0.
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
*
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*
|
|
* NAME
|
|
* lobstream1.js
|
|
*
|
|
* DESCRIPTION
|
|
* SELECTs a CLOB and a BLOB and streams to files.
|
|
*
|
|
* Use demo.sql to create the required table or do:
|
|
* DROP TABLE mylobs;
|
|
* CREATE TABLE mylobs (id NUMBER, c CLOB, b BLOB);
|
|
*
|
|
* Run lobinsert1.js to load data before running this example.
|
|
*
|
|
* This example requires node-oracledb 1.12 or later.
|
|
*
|
|
* This example uses Node 8's async/await syntax.
|
|
*
|
|
*****************************************************************************/
|
|
|
|
var fs = require('fs');
|
|
var oracledb = require('oracledb');
|
|
var dbConfig = require('./dbconfig.js');
|
|
|
|
// Stream a LOB to a file
|
|
async function doStream(lob, outFileName) {
|
|
|
|
const doStreamHelper = new Promise((resolve, reject) => {
|
|
|
|
if (lob.type === oracledb.CLOB) {
|
|
console.log('Writing a CLOB to ' + outFileName);
|
|
lob.setEncoding('utf8'); // set the encoding so we get a 'string' not a 'buffer'
|
|
} else {
|
|
console.log('Writing a BLOB to ' + outFileName);
|
|
}
|
|
|
|
let errorHandled = false;
|
|
|
|
lob.on('error', (err) => {
|
|
// console.log("lob.on 'error' event");
|
|
if (!errorHandled) {
|
|
errorHandled = true;
|
|
lob.close(() => {
|
|
reject(err);
|
|
});
|
|
}
|
|
});
|
|
lob.on('end', () => {
|
|
// console.log("lob.on 'end' event");
|
|
});
|
|
lob.on('close', () => {
|
|
// console.log("lob.on 'close' event");
|
|
if (!errorHandled) {
|
|
resolve();
|
|
}
|
|
});
|
|
|
|
const outStream = fs.createWriteStream(outFileName);
|
|
outStream.on('error', (err) => {
|
|
// console.log("outStream.on 'error' event");
|
|
if (!errorHandled) {
|
|
errorHandled = true;
|
|
lob.close(() => {
|
|
reject(err);
|
|
});
|
|
}
|
|
});
|
|
|
|
// Switch into flowing mode and push the LOB to the file
|
|
lob.pipe(outStream);
|
|
});
|
|
|
|
await doStreamHelper;
|
|
}
|
|
|
|
async function run() {
|
|
let connection;
|
|
|
|
try {
|
|
connection = await oracledb.getConnection(dbConfig);
|
|
|
|
//
|
|
// Fetch a CLOB and stream it
|
|
//
|
|
let result = await connection.execute(`SELECT c FROM mylobs WHERE id = 1`);
|
|
if (result.rows.length === 0) {
|
|
throw new Error("No results. Did you run lobinsert1.js?");
|
|
}
|
|
let lob = result.rows[0][0];
|
|
if (lob === null) {
|
|
throw new Error("LOB was NULL");
|
|
}
|
|
await doStream(lob, 'clobstream1out.txt');
|
|
|
|
//
|
|
// Fetch a BLOB and stream it
|
|
//
|
|
result = await connection.execute(`SELECT b FROM mylobs WHERE id = 2`);
|
|
if (result.rows.length === 0) {
|
|
throw new Error("No results. Did you run lobinsert1.js?");
|
|
}
|
|
lob = result.rows[0][0];
|
|
if (lob === null) {
|
|
throw new Error("LOB was NULL");
|
|
}
|
|
await doStream(lob, 'blobstream1out.jpg');
|
|
|
|
} catch (err) {
|
|
console.error(err);
|
|
} finally {
|
|
if (connection) {
|
|
try {
|
|
await connection.close();
|
|
} catch (err) {
|
|
console.error(err);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
run();
|