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@mxriverlynn
Last active April 16, 2020 05:12
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node-oracledb cursor handling
// set up your oracle stuff ...
function runIt(cb){
// connection and other setup here
var bindvars = {
o_cursor: {
type: oracledb.CURSOR,
dir : oracledb.BIND_OUT
}
};
connection.execute("call schema.cool_proc", bindvars, function(err, out){
// use your standard error handling, here
if (err) { throw err; }
// collection of data
var myCoolStuff = [];
// set up the cursor
var cursor = new Cursor(out.o_cursor);
// handle errors
cursor.on("error", (err) => {/* standard error handler here*/});
// handle data coming through
// each data item is a single record
cursor.on("data", (row) => {
var coolThing = new CoolThing(row);
myCoolThings.push(coolThing);
})
// read it and handle the end of the cursor
cursor.read(() => {
// all done so do stuff with myCoolThings array
cb(myCoolThings);
});
});
}
// do the whole thing and get the rows as an array of my object type
runIt((things) => {
// just loop and log the items for now
things.forEach((thing) => {console.log(thing); });
})
// this code will turn an OUT cursor from the node-oracledb library
// and turn the data into an array objects that has the structure of
// [{NAME: value, NAME_2: value, NAME_N: value}, ...]
// where the NAME is the column name returned through the cursor
//
// Distributed freely under MIT License <http://mutedsolutions.mit-license.org>
// Copyright 2016 Muted Solutions, LLC. All Rights Reserved.
const EventEmitter = require("events");
const util = require("util");
const _ = require("underscore");
// Config
// ------
const defaultNumRows = 500;
// Cursor
// ------
function Cursor(o_cursor, options){
EventEmitter.call(this);
this.options = _.defaults({}, options, {
numRows: defaultNumRows
});
this.o_cursor = o_cursor;
this._configure(o_cursor.metaData);
}
util.inherits(Cursor, EventEmitter);
// Methods
// -------
Cursor.prototype.read = function(cb){
var numRows = this.options.numRows;
this._fetchRows(numRows, cb);
};
Cursor.prototype.close = function(cb){
this.o_cursor.close((err) => {
if (err) { return cb(err); }
return cb();
});
}
// Private API
// -----------
Cursor.prototype._fetchRows = function(numRows, done){
this.o_cursor.getRows(numRows, (err, rows) => {
if (err) { return this.emit("error", err); }
if (rows.length === 0) {
return this.close(done);
}
rows.forEach((row) => {
var rowData = this._getRowData(row);
this.emit("data", rowData);
});
this._fetchRows(numRows, done);
});
}
Cursor.prototype._configure = function(metaData){
this._columnConfig = metaData;
};
Cursor.prototype._getRowData = function(row){
var rowData = {};
row.forEach((dataPoint, index) => {
var rowConfig = this._columnConfig[index];
rowData[rowConfig.name] = dataPoint;
});
return rowData;
};
// Exports
// -------
module.exports = Cursor;
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