CODEWITHSUNDEEP
javascriptnode.jsredis
pretzelhammer
pretzelhammer

Reputation: 15115

node redis client HSET command failing

I have a DAO (data access object) in the current project I'm working on that's an abstraction of a redis db. Here's all of the code that is going to be relevant to my upcoming question below:

var redis = require("redis");
var _ = require("underscore");
var exceptions = require("./exceptions");

function Dao (port, address) {
    var self = this;

    console.log("Connecting to redis @ %s:%s", address, port);
    var client = redis.createClient(port, address);

    function incrCount (callback) {
        client.incr("count", callback);
    };

    this.getPages = function (callback) {
        client.hgetall("pages", function (err, pages) {
            if (err) {
                callback(err);
            } else if (!pages) {
                callback(exceptions.NoPages);
            } else {
                callback(err, _.reduce(Object.keys(pages), function (array, id) {
                    array.push(JSON.parse(pages[id]));
                    return array;
                }, []));        
            }
        });
    };

    this.createPage = function (page, callback) {
        incrCount(function (err, results) {
            if (err) {
                callback(err);
            } else {
                page.id = results;
                self.updatePage(page);
                callback(err, {id: results});
            }
        });
    };

    this.updatePage = function (page) {
        client.hset("pages", page.id, JSON.stringify(page));
    };
};

Whenever I use this object, for example:

function printResults (err, results) {
    console.log(err || results);
};

var dao = new Dao(port, address);
dao.createPage({testpage: "testcontent"}); // DOES NOT ADD PAGE TO DB, I HAVE NOT IDEA WHY, HOWEVER COUNT IS INCREMENTED TO 1 AS IT SHOULD BE
dao.getPages(printResults); // PRINTS ERROR: NO PAGES EXIST IN DB
dao.updatePage({id: 1, testpage: "testcontent"}); // ADDS PAGE TO DB, AND THIS IS EXACTLY HOW THE FUNCTION WOULD HAVE BEEN CALLED INTERNALLY BY CREATEPAGE() ABOVE
dao.getPages(printResults); // RETURNS TEST PAGE

What makes no sense is that createPage() calls updatePage() under the hood! Why are pages only created in the DB when I call updatePage() directly? createPage() doesn't actually add any pages to redis even though it's also just calling updatePage().

EDIT (resolved): Apparently the tests I was running were closing the DB connection before it had a chance to fully receive/process the createPage calls, I added a setTimeout(db.close(), 2000) to the end of my tests and it works now.

Upvotes: 0

Views: 1565

Answers (1)

Barış Uşaklı
Barış Uşaklı

Reputation: 13532

You are not waiting on the callback for hset I would change it so it uses a callback.

this.createPage = function (page, callback) {
    incrCount(function (err, results) {
        if (err) {
            callback(err);
        } else {
            page.id = results;
            self.updatePage(page, function(err) {
                 callback(err, {id: results});
            });                
        }
    });
};

this.updatePage = function (page, callback) {
    client.hset("pages", page.id, JSON.stringify(page), callback);
};

Then change your code to see if it makes any difference

var dao = new Dao(port, address);
dao.createPage({testpage: "testcontent"}, function(err, page) {
    if (err) {
       return console.log(err)
    }
    dao.getPages(printResults); 
});

The problem with the below code is getPages may be called before the incr and hset are done, so it returns no pages.

dao.createPage({testpage: "testcontent"}); 
dao.getPages(printResults);

Upvotes: 1

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