如何解决如何从 node-oracledb toQueryStream() 作为 Promise 检索值
在尝试使用 resultSet
从 toQueryStream()
获取行时,我只能在控制台中找到行。但无法使用 Promise 返回值,因为 toQueryStream()
函数使用 eventListener
来解析行。我的代码如下,请建议获取行值。
function getPosCounter() {
return oracledb.getConnection(kcdConnStr)
.then(function (conn) {
return conn.execute(`BEGIN GETPOSCOUNTER(:CV_1); END;`,{ // EXECUTE ORACLE PROCEDURE
CV_1: { dir: oracledb.BIND_OUT,type: oracledb.CURSOR } //CURSOR DEFINED FOR OUT PARAM
})
.then((result) => {
var resRows = new Array();
var resultSet = result.outBinds.CV_1; //RESULT SET FOR OUTPUT
var queryStream = resultSet.toQueryStream(); //QUERYSTREAM INITIALIZED FOR CURSOR VALUES
var consumeStream = new Promise((resolve,reject) => {
queryStream.on('data',function (row) {
console.log(row);
});
queryStream.on('error',reject);
queryStream.on('close',resolve);
})
.then(rows => {
console.dir(rows); //RETURN ROW VALUES
});
})
.catch((err) => {
conn.close();
console.error(err);
return 'failure';
})
});
}
解决方法
在我遇到这个问题之前,我不知道 nodeJs-Stream
功能对我来说很难理解。所以我在 Oracle Community 上找到了关于从结果集中获取行的文档。通过以下方式使其成为可能。
function getPosCounter() {
return oracledb.getConnection(kcdConnStr)
.then(function (conn) {
return conn.execute(`BEGIN USP_POSCOUNTER(:CV_1); END;`,{ // EXECUTE ORACLE PROCEDURE
CV_1: { dir: oracledb.BIND_OUT,type: oracledb.CURSOR } //CURSOR DEFINED FOR OUT PARAM
})
.then((result) => {
var resRows = [];
var resultSet = result.outBinds.CV_1; //RESULT SET FOR OUTPUT
var queryStream = resultSet.toQueryStream(); //QUERYSTREAM INITIALIZED FOR CURSOR VALUES
return consumeStream = new Promise((resolve,reject) => {
queryStream.on('data',(row) => {
resRows.push(row); //STORE ROWS IN TO BLANK ARRAY
});
queryStream.on('error',reject);
queryStream.on('close',() => {
resolve(resRows); //RETURN ON RESOLVING ALL THE ROWS
conn.close();
});
});
})
.catch((err) => {
conn.close();
//console.error(err);
return 'failure';
})
});
}
,
您可以这样编写代码,而不是摆弄 Promise 和流:
const oracledb = require('oracledb');
const dbConfig = require('./dbconfig.js');
if (process.platform === 'darwin') {
oracledb.initOracleClient({libDir: process.env.HOME + '/Downloads/instantclient_19_8'});
}
async function run() {
let connection;
try {
connection = await oracledb.getConnection(dbConfig);
await connection.execute(
`create or replace procedure usp_poscounter(p out sys_refcursor) as
begin
open p for select postal_code from locations order by location_id;
end;`);
const r = await getPosCounter();
console.dir(r,{ depth: null });
} catch (err) {
console.error(err);
} finally {
if (connection) {
try {
await connection.close();
} catch (err) {
console.error(err);
}
}
}
}
async function getPosCounter() {
let conn;
try {
conn = await oracledb.getConnection(dbConfig); // should really use a pool instead
const result = await conn.execute(
`BEGIN USP_POSCOUNTER(:CV_1); END;`,{ CV_1: { dir: oracledb.BIND_OUT,type: oracledb.CURSOR } }
);
let row,outRows = [];
while ((row = await result.outBinds.CV_1.getRow())) {
outRows.push(row);
}
// With node-oracledb 5.2 you will be able to simplify this loop to be the
// following one line. Note with any node-oracledb version,if the number
// of rows is large,then you will want your architecture to deal with
// batches of rows insteading of returning one big array.
//
// const outRows = await result.outBinds.CV_1.getRows(); // empty arg gets all rows
return (outRows);
} catch (err) {
console.error(err);
} finally {
if (conn) {
try {
await conn.close();
} catch (err) {
console.error(err);
}
}
}
}
run();
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