I'm fairly new to Node.js and I'm trying to create a blog using Express and Redis.
My problem is that I'm kind of lost in NoSQL and I can't really see how I should design my Redis data.
I wanted to do :
SET global:postsNb 0
SET posts:1:text blablabla
SADD posts:1:tags a
SADD posts:1:tags b
SADD posts:1:tags c
It seems quite natural but I don't know how I can search all posts where a in tags.
Could you help me pls ?
Thanks in advance.
It seems quite natural but I don't know how I can search all posts where a in tags.
You will need somthing like:
SADD tags:[tagname] [postId]
e.g, when creating a post (with id=1, tags=a,b,c, content=...) run the following commands:
SADD tags:a 1
SADD tags:b 1
SADD tags:c 1
Then to retrieve all posts that have the tag a:
SMEMBERS tags:a
Now with the retrieved ids just fetch each posts you need to display.
PS: HASH are more convenient than strings for storing blog posts, so instead of:
SET posts:1:text
you may want to use HMSET instead
HMSET posts:1 text blablabla createdAt 1385547056549
it will allow you to add more attributes/metadata to the post while still retrieving it easily with HGETALL or HMGET.
Related
i am trying to filter records using key.For example
localhost:5984/school/_design/school/_view/schoolstats?startkey=[Name,DOB,AGE]&endkey=[Name,DOB,AGE]
1)filter using Name only
2)filter using Name and Age only
3)filter using Name and DOB only
4)filter using Age only
I have tried a lot using wildcard in couchdb but cant able to fetch the exact result.
If you use a ranged query with startkey and endkey, the order of keys is not changeable.
These combination should be working. If you need other combination you have to emit your multikey in the desired form.
startkey=[Name]&endkey=[Name,{}]
startkey=[Name,DOB]&endkey=[Name,{}]
startkey=[Name,DOB,AGE]&endkey=[Name,{}]
startkey=[Name,DOB]&endkey=[Name,DOB,{}]
For your asked filters, you have to emit two more keys/multikeys in your map function.
I think, if you do not change your emitting keys, aka, you have a emitting statement like: emit [Name,DOB,AGE], null
1)Filter using Name only
startkey=[Name]&endkey=[Name,{}]
2)Filter using Name and Age only
Can not
3)Filter using Name and DOB only
startkey=[Name,DOB]&endkey=[Name,DOB,{}]
4)Filter using Age only
Can not
I get this
SEARCH-BADORDERBY: (err:FOER0000) Indexes are required to support element, element-attribute, json-property, or field sort specifications
everytime i try to use the orderBy. I tried in all possible ways.
qb.where(qb.value("hasGeolocation", true)).orderBy("username")
or
qb.where(qb.value("hasGeolocation", true)).orderBy(qb.property("username"))
or
qb.where(qb.value("hasGeolocation", true)).orderBy(qb.sort("username"))
or
qb.where(qb.value("hasGeolocation", true)).orderBy(qb.sort(qb.property("username")))
and for the sort i tried with 'ascending' or 'descending' direction. Nothing works. Am I doing something wrong or is there something wrong with the MarkLogic Node Api?
Victor, it looks to me like you haven't defined a range index on "username". Define a string range index on "username" and I think you'll be set.
I'm writing a REST api in node js that will execute a sql query and send the results;
in the request I need to send the WHERE conditions; ex:
GET 127.0.0.1:5007/users //gets the list of users
GET 127.0.0.1:5007/users
id = 1 //gets the user with id 1
Right now the conditions are passed from the client to the rest api in the request's headers.
In the API I'm using sequelize, an ORM that needs to receive WHERE conditions in a particular form (an object); ex: having the condition:
(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)
this needs to be formatted as a nested object:
-- x=1
-- AND -| -- y=2
| -- OR ----|
| -- z=3
-- OR -|
|
| -- x=3
-- AND -|
-- y=1
so the object would be:
Sequelize.or (
Sequelize.and (
{x=1},
Sequelize.or(
{y=2},
{z=3}
)
),
Sequelize.and (
{x=3},
{y=1}
)
)
Now I'm trying to pass a simple string (like "(x=1 AND (y=2 OR z=3)) OR (x=3 AND y=1)"), but then I will need a function on the server that can convert the string in the needed object (this method in my opinion has the advantage that the developer writing the client, can pass the where conditions in a simple way, like using sql, and this method is also indipendent from the used ORM, with no need to change the client if we need to change the server or use a different ORM);
The function to read and convert the conditions' string into an object is giving me headache (I'm trying to write one without success, so if you have some examples about how to do something like this...)
What I would like to get is a route capable of executing almost any kind of sql query and give the results:
now I have a different route for everything:
127.0.0.1:5007/users //to get all users
127.0.0.1:5007/users/1 //to get a single user
127.0.0.1:5007/lastusers //to get user registered in the last month
and so on for the other tables i need to query (one route for every kind of request I need in the client);
instead I would like to have only one route, something like:
127.0.0.1:5007/request
(when calling this route I will pass the table name and the conditions' string)
Do you think this solution would be a good solution or you generally use other ways to handle this kind of things?
Do you have any idea on how to write a function to convert the conditions' string into the desired object?
Any suggestion would be appreciated ;)
I would strongly advise you not to expose any part of your database model to your clients. Doing so means you can't change anything you expose without the risk of breaking the clients. One suggestion as far as what you've supplied is that you can and should use query parameters to cut down on the number of endpoints you've got.
GET /users //to get all users
GET /users?registeredInPastDays=30 //to get user registered in the last month
GET /users/1 //to get a single user
Obviously "registeredInPastDays" should be renamed to something less clumsy .. it's just an example.
As far as the conditions string, there ought to be plenty of parsers available online. The grammar looks very straightforward.
IMHO the main disadvantage of your solution is that you are creating just another API for quering data. Why create sthm from scratch if it is already created? You should use existing mature query API and focus on your business logic rather then inventing sthm new.
For example, you can take query syntax from Odata. Many people have been developing that standard for a long time. They have already considered different use cases and obstacles for query API.
Resources are located with a URI. You can use or mix three ways to address them:
Hierarchically with a sequence of path segments:
/users/john/posts/4711
Non hierarchically with query parameters:
/users/john/posts?minVotes=10&minViews=1000&tags=java
With matrix parameters which affect only one path segment:
/users;country=ukraine/posts
This is normally sufficient enough but it has limitations like the maximum length. In your case a problem is that you can't easily describe and and or conjunctions with query parameters. But you can use a custom or standard query syntax. For instance if you want to find all cars or vehicles from Ford except the Capri with a price between $10000 and $20000 Google uses the search parameter
q=cars+OR+vehicles+%22ford%22+-capri+%2410000..%2420000
(the %22 is a escaped ", the %24 a escaped $).
If this does not work for your case and you want to pass data outside of the URI the format is just a matter of your taste. Adding a custom header like X-Filter may be a valid approach. I would tend to use a POST. Although you just want to query data this is still RESTful if you treat your request as the creation of a search result resource:
POST /search HTTP/1.1
your query-data
Your server should return the newly created resource in the Location header:
HTTP/1.1 201 Created
Location: /search/3
The result can still be cached and you can bookmark it or send the link. The downside is that you need an additional POST.
I am using websockets , nodejs v0.10.12 and also PostgreSQL 9.1, with PostGIS 2.0.
Now, on websockets, on the server side, in order to gather textual data and send them to the client I perform a query using node's pg plugin.
I have something like
var query = client.query('SELECT p_name,p_date FROM pins WHERE p_id ='+ja)
//send them and render in client as html
query.on("row", function (row, result) {result.addRow(row);});
query.on("end", function (result) {
for (var i=0; i<result.rows.length; i++){
connection.send(
'Name</br>'
+result.rows[i].p_name+
'</br>Date</br>'
+result.rows[i].p_date+
'</br>'
}
client.end();
});
Now, here is the tricky part. I want to render the date like 25/02/2012.
With the above code, I get Sat Feb 02 2002 02:00:00 GMT+0200 (Χειμερινή ώρα GTB)
To get DD/MM/YYYY I have to put a line of code like
SET datestyle = "SQL, DMY";
This is apparently PHP and I am using Javascript because I work with websockets.
The only thing I could think of is editing the above query like so
var query = client.query('SET datestyle = "SQL, DMY"; SELECT p_name,p_date FROM pins WHERE p_id ='+ja)
I dont get any errors, but on the client the date renders null.
How can I fix this?
Thanks
OK. Where to start?
This:
var query = client.query('SELECT p_name,p_date FROM pins WHERE p_id ='+ja)
is not the correct way to build a query. Used a parameterised query and protect yourself from SQL injection.
SET datestyle = "SQL, DMY";
This is apparently PHP and I am using Javascript because I work with websockets.
What? I'm trying to think of something constructive about this sentence, but the best I can think of is "What?". It is far from apparent that the above is PHP, because it isn't. The fact that you are sending it to the database ought to give you a hint that it's SQL. Also, you're not using javascript because you work with websockets. You're using javascript because you're using javascript - websockets are nothing to do with anything here.
The only thing I could think of...
Doesn't include looking in the manuals.
Go to the PostgreSQL website, click through to the documentation and manuals, and on the contents page click "Functions and Operators" and then "Data type formatting functions". Here is the link for you:
http://www.postgresql.org/docs/current/static/functions-formatting.html
You'll notice that the PostgreSQL developers not only produce extensive and detailed manuals, but they keep multiple versions online and make it simple to switch back and fore to see what's changed.
There is a whole section on this page on how to format date-times in different ways, with clear descriptions of each effect. I didn't find this using the documentation search or anything clever like that - just the obvious links on each page.
If you did a search you would find plenty on the datestyle parameter, and a little further digging would show that you can set it per-session or as a default for a given user or database.
Finally though, don't do it that way at all. Return ISO-standard date formats like #mu said (YYYY-MM-DD etc). and format them in your javascript client code.
Oh - while I'm no expert, I'm not sure that </br> is valid HTML, XHTML or XML either. Did you perhaps mean <br/>?
I have a view wich returns several elements with array keys.
Example :
{"total_rows":4,"offset":0,"rows":[
{"id":"","key":[15,"2"],"value":1,"doc":{},
{"id":"","key":[20,"2"],"value":1,"doc":{},
{"id":"","key":[20,"3"],"value":1,"doc":{},
{"id":"","key":[20,"4"],"value":1,"doc":{}
]}
I'm trying to search through those elements. So if I do the following request :
/database/_design/element/_view/all/?
startkey=[15, "2"]&
endkey=[20, "3"]&
include_docs=true&reduce=false
Live example : http://jchris.couchone.com/keyhuh/_design/Record/_view/by_CreationDate_and_BoreholeName?startkey=[1267686720,%22sp4%22]&endkey=[1267686725,%22sp4\u9999%22]&include_docs=true&reduce=false
This one doesn't works. It returns me all the records, even the last one, which doesn't meets the second element of the array.
Strangely enough, it works with strings only.
Example :
{"total_rows":4,"offset":0,"rows":[
{"id":"","key":["15","2"],"value":1,"doc":{},
{"id":"","key":["20","2"],"value":1,"doc":{},
{"id":"","key":["20","3"],"value":1,"doc":{},
{"id":"","key":["20","4"],"value":1,"doc":{}
]}
if I do the following request :
/database/_design/element/_view/all/?
startkey=["15", "2"]&
endkey=["20", "3"]&
include_docs=true&
reduce=false
Live Example : http://jchris.couchone.com/keyhuh/_design/Record/_view/by_Client_and_BoreholeName?startkey=[%22Test1%22,%22sp4%22]&endkey=[%22Test1%22,%22sp4\u9999%22]&include_docs=true&reduce=false
Here it'll work well and only return the three first elements.
Am I missing something with couchdb's search for arrays with integers and strings ? Or have I fallen on a bug ?
Note : it does the same with CouchDB 0.10 and 0.11.
This looks wrong, and there are a few things it could be. Is it possible for you to share your code with us? If the data isn't proprietary you could replicate your db to http://jchris.couchone.com/keyhuh and I'll take a look at the whole thing there.
...
Thanks for posting the live data. This is the query that is busted?
http://jchris.couchone.com/keyhuh/_design/Record/_view/by_Client_and_BoreholeName?startkey=[%22Test1%22,%22sp4%22]&endkey=[%22Test1%22,%22sp4\u9999%22]&reduce=false
Because that looks fine to me. What am I missing?