I'm trying to make a pagination system for a table with datas from mongoose.
Actually I know how to do it but I wonder which method is the best :
Method 1: Only with mongoose
var perPage = 15
, page = req.param('page') > 0 ? req.param('page') -1 : 0
res.locals.createPagination = function (pages, page) {
var url = require('url')
, qs = require('querystring')
, params = qs.parse(url.parse(req.url).query)
, str = ''
params.page = 1
for (var p = 1; p < pages + 1; p++) {
params.page = p
clas = page+1 == p ? "active" : "no"
str += '<li class="'+clas+'">'+ p +'</li>'
}
return str
}
Vente.find({})
.populate({ path: 'user_id', select: 'username server -_id'})
.limit(perPage)
.skip(perPage * page)
.sort({created_at: 'desc'})
.exec(function(err, ventes){
Vente.count({}, function(err, count){
res.render('index', {
page: page,
pages: count / perPage,
user: req.user,
items: ventes,
});
});
});
})
and in my jade file i have this :
if (pages > 1)
ul.pagination
!= createPagination(pages, page)
It works very well, I send to the jade file only 15 elements.
Method 2: With Datatable
In my .jade file I just have to add :
script(type="text/javascript")
$(document).ready(function() {
$("#tab").dataTable();
});
script(type="text/javascript",src="http://ajax.aspnetcdn.com/ajax/jquery.dataTables/1.9.4/jquery.dataTables.min.js")
But I have to send to my .jade all elements
So my question is : Is the First method better ? The second method let the user search faster and pagination doesn't need to refresh the page.
Thanks.
DataTable is very cool (I personally use it). Luckily Datatable has a way to load the content server side, it is cool because you get a lot of stuff for free. Probably just a matter of changing a bit the way you return the data.
Method 2, loading everything, will just not work in the long run, too much data to load.
Method 1, is ok, but I would go with a mix of the two. DataTable server side, as explained above.
Related
I use MongoDBClient in Node.js, and Pug.
I would want to get all my pizzerias' name in my database. Thus, I wrote this line : collection.find({cook:'Pizza'}) to select all the pizzerias, and the attribute "name" exists.
But find returns a cursor, thus I can't directly use its return like that : var array_pizzerias_names = collection.find({cook:'Pizza'}).get('name'). (NB : I know the funciton get doesn't exist).
How could I do it ?
In my Pug file, I wrote these few lines :
- for(var i = 0; i < array_pizzerias_names.length; i++) {
p=array_pizzerias_names[i].name
- }
I found a solution.
MongoClient (require('mongodb').MongoClient) provides a find method signature which takes 2 parameters, and the second is a callback ; the last parameter of the latter is a cursor which have a method toArray.
The method toArray takes a callback ; its last parameter is the array containing all the results of the find, and can be used in Pug.
The below code works.
Node.js code (JavaScript file) :
collection.find({cuisine: speciality}, (error, cursor) => {
handleError(error, res);
cursor.toArray((error, array_results) => {
handleError(error, res);
app.locals.speciality = speciality;
app.locals.array_documents = array_results;
res.render("speciality.pug");
});
});
Pug file :
doctype html
html(lang='fr')
head
title='Speciality'
body
h1 Speciality : #{speciality} - Number of buildings : #{array_documents.length}
- for(var i = 0; i < array_documents.length; i++) {
p=array_documents[i].name + " - Address : " + array_documents[i].address.street + " " + array_documents[i].borough + ", building n°" + array_documents[i].address.building
- }
I am wondering how can I achieve pagination using Cassandra.
Let us say that I have a blog. The blog lists max 10 posts per page. To access next posts a user must click on pagination menu to access page 2 (posts 11-20), page 3 (posts 21-30), etc.
Using SQL under MySQL, I could do the following:
SELECT * FROM posts LIMIT 20,10;
The first parameter of LIMIT is offset from the beginning of result set and second argument is amount of rows to fetch. The example above returns 10 rows starting from row 20.
How can I achieve the same effect in CQL?
I have found some solutions on Google, but all of them require to have "the last result from previous query". It works for having "next" button to paginate to another 10-results-set, but what if I want to jump from page 1 to page 5?
You don't need to use tokens, if you are using Cassandra 2.0+.
Cassandra 2.0 has auto paging.
Instead of using token function to create paging, it is now a built-in feature.
Now developers can iterate over the entire result set, without having to care that it’s size is larger than the memory. As the client code iterates over the results, some extra rows can be fetched, while old ones are dropped.
Looking at this in Java, note that SELECT statement returns all rows, and the number of rows retrieved is set to 100.
I’ve shown a simple statement here, but the same code can be written with a prepared statement, couple with a bound statement. It is possible to disable automatic paging, if it is not desired. It is also important to test various fetch size settings, since you will want to keep the memorize small enough, but not so small that too many round-trips to the database are taken. Check out this blog post to see how paging works server side.
Statement stmt = new SimpleStatement(
"SELECT * FROM raw_weather_data"
+ " WHERE wsid= '725474:99999'"
+ " AND year = 2005 AND month = 6");
stmt.setFetchSize(24);
ResultSet rs = session.execute(stmt);
Iterator<Row> iter = rs.iterator();
while (!rs.isFullyFetched()) {
rs.fetchMoreResults();
Row row = iter.next();
System.out.println(row);
}
Try using the token function in CQL:
https://docs.datastax.com/en/cql-oss/3.3/cql/cql_using/useToken.html
Another suggestion, if you are using DSE, solr supports deep paging:
https://cwiki.apache.org/confluence/display/solr/Pagination+of+Results
Manual Paging
The driver exposes a PagingState object that represents where we were in the result set when the last page was fetched:
ResultSet resultSet = session.execute("your query");
// iterate the result set...
PagingState pagingState = resultSet.getExecutionInfo().getPagingState();
This object can be serialized to a String or a byte array:
String string = pagingState.toString();
byte[] bytes = pagingState.toBytes();
This serialized form can be saved in some form of persistent storage to be reused later. When that value is retrieved later, we can deserialize it and reinject it in a statement:
PagingState pagingState = PagingState.fromString(string);
Statement st = new SimpleStatement("your query");
st.setPagingState(pagingState);
ResultSet rs = session.execute(st);
Note that the paging state can only be reused with the exact same statement (same query string, same parameters). Also, it is an opaque value that is only meant to be collected, stored an re-used. If you try to modify its contents or reuse it with a different statement, the driver will raise an error.
Src: https://docs.datastax.com/en/cql-oss/3.3/cql/cql_reference/cqlshPaging.html
If you read this doc "Use paging state token to get next result",
https://datastax.github.io/php-driver/features/result_paging/
We can use "paging state token" to paginate at application level.
So PHP logic should look like,
<?php
$limit = 10;
$offset = 20;
$cluster = Cassandra::cluster()->withContactPoints('127.0.0.1')->build();
$session = $cluster->connect("simplex");
$statement = new Cassandra\SimpleStatement("SELECT * FROM paging_entries Limit ".($limit+$offset));
$result = $session->execute($statement, new Cassandra\ExecutionOptions(array('page_size' => $offset)));
// Now $result has all rows till "$offset" which we can skip and jump to next page to fetch "$limit" rows.
while ($result->pagingStateToken()) {
$result = $session->execute($statement, new Cassandra\ExecutionOptions($options = array('page_size' => $limit,'paging_state_token' => $result->pagingStateToken())));
foreach ($result as $row) {
printf("key: '%s' value: %d\n", $row['key'], $row['value']);
}
}
?>
Although the count is available in CQL, so far I have not seen a good solution for the offset part...
So... one solution I have been contemplating was to create sets of pages using a background process.
In some table, I would create the blog page A as a set of references to page 1, 2, ... 10. Then another entry for blog page B pointing to pages 11 to 20, etc.
In other words, I would build my own index with a row key set to the page number. You may still make it somewhat flexible since you can offer the user to choose to see 10, 20 or 30 references per page. For example, when set to 30, you display sets 1, 2, and 3 as page A, sets 4, 5, 6 as page B, etc.)
And if you have a backend process to handle all of that, you can update your lists as new pages are added and old pages are deleted from the blog. The process should be really fast (like 1 min. for 1,000,000 rows if even that slow...) and then you can find the pages to display in your list pretty much instantaneously. (Obviously, if you are to have thousands of users each posting hundreds of pages... that number can grow quickly.)
Where it becomes more complicated is if you wanted to offer a complex WHERE clause. By default a blog shows you a list of all the posts from the newest to the oldest. You could also offer lists of posts with tag Cassandra. Maybe you want to inverse the order, etc. That makes it difficult unless you have some form of advanced way to create your index(es). On my end I have a C-like language which goes and peek and poke to the values in a row to (a) select them and if selected (b) to sort them. In other words, on my end I can already have WHERE clauses as complex as what you'd have in SQL. However, I do not yet break up my lists in pages. Next step I suppose...
Using cassandra-node driver for node js (koa js,marko js) : Pagination
Problem
Due to the absence of skip functionality, we need to work around. Below is the implementation of manual paging for node app in case of anyone can get an idea.
code for simple users list
navigate between next and previous page states
easy to replicate
There are two solutions which i am going to state here but only gave the code for solution 1 below,
Solution 1 : Maintain page states for next and previous records (maintain stack or whatever data structure best fit)
Solution 2 : Loop through all records with limit and save all possible page states in variable and generate pages relatively to their pageStates
Using this commented code in model, we can get all states for pages
//for the next flow
//if (result.nextPage) {
// Retrieve the following pages:
// the same row handler from above will be used
// result.nextPage();
//}
Router Functions
var userModel = require('/models/users');
public.get('/users', users);
public.post('/users', filterUsers);
var users = function* () {//get request
var data = {};
var pageState = { "next": "", "previous": "" };
try {
var userCount = yield userModel.Count();//count all users with basic count query
var currentPage = 1;
var pager = yield generatePaging(currentPage, userCount, pagingMaxLimit);
var userList = yield userModel.List(pager);
data.pageNumber = currentPage;
data.TotalPages = pager.TotalPages;
console.log('--------------what now--------------');
data.pageState_next = userList.pageStates.next;
data.pageState_previous = userList.pageStates.previous;
console.log("next ", data.pageState_next);
console.log("previous ", data.pageState_previous);
data.previousStates = null;
data.isPrevious = false;
if ((userCount / pagingMaxLimit) > 1) {
data.isNext = true;
}
data.userList = userList;
data.totalRecords = userCount;
console.log('--------------------userList--------------------', data.userList);
//pass to html template
}
catch (e) {
console.log("err ", e);
log.info("userList error : ", e);
}
this.body = this.stream('./views/userList.marko', data);
this.type = 'text/html';
};
//post filter and get list
var filterUsers = function* () {
console.log("<------------------Form Post Started----------------->");
var data = {};
var totalCount;
data.isPrevious = true;
data.isNext = true;
var form = this.request.body;
console.log("----------------formdata--------------------", form);
var currentPage = parseInt(form.hdpagenumber);//page number hidden in html
console.log("-------before current page------", currentPage);
var pageState = null;
try {
var statesArray = [];
if (form.hdallpageStates && form.hdallpageStates !== '') {
statesArray = form.hdallpageStates.split(',');
}
console.log(statesArray);
//develop stack to track paging states
if (form.hdpagestateRequest === 'next') {
console.log('--------------------------next---------------------');
currentPage = currentPage + 1;
statesArray.push(form.hdpageState_next);
pageState = form.hdpageState_next;
}
else if (form.hdpagestateRequest === 'previous') {
console.log('--------------------------pre---------------------');
currentPage = currentPage - 1;
var p_st = statesArray.length - 2;//second last index
console.log('this index of array to be removed ', p_st);
pageState = statesArray[p_st];
statesArray.splice(p_st, 1);
//pageState = statesArray.pop();
}
else if (form.hdispaging === 'false') {
currentPage = 1;
pageState = null;
statesArray = [];
}
data.previousStates = statesArray;
console.log("paging true");
totalCount = yield userModel.Count();
var pager = yield generatePaging(form.hdpagenumber, totalCount, pagingMaxLimit);
data.pageNumber = currentPage;
data.TotalPages = pager.TotalPages;
//filter function - not yet constructed
var searchUsers = yield userModel.searchList(pager, pageState);
data.usersList = searchUsers;
if (searchUsers.pageStates) {
data.pageStates = searchUsers.pageStates;
data.next = searchUsers.nextPage;
data.pageState_next = searchUsers.pageStates.next;
data.pageState_previous = searchUsers.pageStates.previous;
//show previous and next buttons accordingly
if (currentPage == 1 && pager.TotalPages > 1) {
data.isPrevious = false;
data.isNext = true;
}
else if (currentPage == 1 && pager.TotalPages <= 1) {
data.isPrevious = false;
data.isNext = false;
}
else if (currentPage >= pager.TotalPages) {
data.isPrevious = true;
data.isNext = false;
}
else {
data.isPrevious = true;
data.isNext = true;
}
}
else {
data.isPrevious = false;
data.isNext = false;
}
console.log("response ", searchUsers);
data.totalRecords = totalCount;
//pass to html template
}
catch (e) {
console.log("err ", e);
log.info("user list error : ", e);
}
console.log("<------------------Form Post Ended----------------->");
this.body = this.stream('./views/userList.marko', data);
this.type = 'text/html';
};
//Paging function
var generatePaging = function* (currentpage, count, pageSizeTemp) {
var paging = new Object();
var pagesize = pageSizeTemp;
var totalPages = 0;
var pageNo = currentpage == null ? null : currentpage;
var skip = pageNo == null ? 0 : parseInt(pageNo - 1) * pagesize;
var pageNumber = pageNo != null ? pageNo : 1;
totalPages = pagesize == null ? 0 : Math.ceil(count / pagesize);
paging.skip = skip;
paging.limit = pagesize;
paging.pageNumber = pageNumber;
paging.TotalPages = totalPages;
return paging;
};
Model Functions
var clientdb = require('../utils/cassandradb')();
var Users = function (options) {
//this.init();
_.assign(this, options);
};
Users.List = function* (limit) {//first time
var myresult; var res = [];
res.pageStates = { "next": "", "previous": "" };
const options = { prepare: true, fetchSize: limit };
console.log('----------did i appeared first?-----------');
yield new Promise(function (resolve, reject) {
clientdb.eachRow('SELECT * FROM users_lookup_history', [], options, function (n, row) {
console.log('----paging----rows');
res.push(row);
}, function (err, result) {
if (err) {
console.log("error ", err);
}
else {
res.pageStates.next = result.pageState;
res.nextPage = result.nextPage;//next page function
}
resolve(result);
});
}).catch(function (e) {
console.log("error ", e);
}); //promise ends
console.log('page state ', res.pageStates);
return res;
};
Users.searchList = function* (pager, pageState) {//paging filtering
console.log("|------------Query Started-------------|");
console.log("pageState if any ", pageState);
var res = [], myresult;
res.pageStates = { "next": "" };
var query = "SELECT * FROM users_lookup_history ";
var params = [];
console.log('current pageState ', pageState);
const options = { pageState: pageState, prepare: true, fetchSize: pager.limit };
console.log('----------------did i appeared first?------------------');
yield new Promise(function (resolve, reject) {
clientdb.eachRow(query, [], options, function (n, row) {
console.log('----Users paging----rows');
res.push(row);
}, function (err, result) {
if (err) {
console.log("error ", err);
}
else {
res.pageStates.next = result.pageState;
res.nextPage = result.nextPage;
}
//for the next flow
//if (result.nextPage) {
// Retrieve the following pages:
// the same row handler from above will be used
// result.nextPage();
//}
resolve(result);
});
}).catch(function (e) {
console.log("error ", e);
info.log('something');
}); //promise ends
console.log('page state ', pageState);
console.log("|------------Query Ended-------------|");
return res;
};
Html side
<div class="box-footer clearfix">
<ul class="pagination pagination-sm no-margin pull-left">
<if test="data.isPrevious == true">
<li><a class='submitform_previous' href="">Previous</a></li>
</if>
<if test="data.isNext == true">
<li><a class="submitform_next" href="">Next</a></li>
</if>
</ul>
<ul class="pagination pagination-sm no-margin pull-right">
<li>Total Records : $data.totalRecords</li>
<li> | Total Pages : $data.TotalPages</li>
<li> | Current Page : $data.pageNumber</li>
</ul>
</div>
I am not very much experienced with node js and cassandra db, this solution can surely be improved. Solution 1 is working example code to start with the paging idea. Cheers
a detailed blog.
Our use case was similar. Pull everything from a Cassandra table (cassandra does it smartly by fetching ~5000 in one go and return a cursor), heavy personalized processing on each row, and keep going. Once our iteration reaches close to 5000, it again fetches the next chunk of 5000 rows internally and adds it to the result cursor. It does it so brilliantly that we don’t even feel this magic happening behind the scene.
but It became a bottleneck for us.As iterating over the chunk took some time and till it reached the end of the chunk, Cassandra thought the connection was not being used and closed the connection automatically yelling, its timeout. So we implemented with page state.
from cassandra.cluster import Cluster
from cassandra.auth import PlainTextAuthProvider
from cassandra.query import SimpleStatement
# connection with cassandra
cluster = Cluster(["127.0.0.1"], auth_provider=PlainTextAuthProvider(username="pankaj", password="pankaj"))
session = cluster.connect()
# setting keyspace
session.set_keyspace("my_keyspace")
# set fetch size
fetch_size = 100
# It will print first 100 records
next_page_available = True
paging_state = None
data_count = 0
while next_page_available is True:
# fetches a new chunk with given page state
result = fetch_a_fresh_chunk(paging_state)
paging_state = results.paging_state
for result in results:
# process payload here.....
# payload processed
data_count += 1
# once we reach fetch size, we stop cassandra to fetch more chunk, internally
if data_count == fetch_size:
i = 0
break
# fetches a fresh chunk with given page state
def fetch_a_fresh_chunk(paging_state = None)
query = "SELECT * FROM my_cute_cassandra_table;"
statement = SimpleStatement(query, fetch_size = fetch_size)
results = session.execute(statement, paging_state=paging_state)
In trying to implement a filterToolbar search in jquery, but when I write in the textbox it doesnt send the value, the search field nor the operator: I used an example, here is the code in html file
jQuery(document).ready(function () {
var grid = $("#list");
$("#list").jqGrid({
url:'grid.php',
datatype: 'xml',
mtype: 'GET',
deepempty:true ,
colNames:['Id','Buscar','Desccripcion'],
colModel:[
{name:'id',index:'id', width:65, sorttype: 'int', hidden:true, search:false},
{name:'examen',index:'nombre', width:500, align:'left', search:true},
{name:'descripcion',index:'descripcion', width:100, sortable:false, hidden:true, search:false}
],
pager: jQuery('#pager'),
rowNum:25,
sortname: 'nombre',
sortorder: 'asc',
viewrecords: true,
gridview: true,
height: 'auto',
caption: 'Examenes',
height: "100%",
loadComplete: function() {
var ids = grid.jqGrid('getDataIDs');
for (var i=0;i<ids.length;i++) {
var id=ids[i];
$("#"+id+ " td:eq(1)", grid[0]).tooltip({
content: function(response) {
var rowData = grid.jqGrid('getRowData',this.parentNode.id);
return rowData.descripcion;
},
open: function() {
$(this).tooltip("widget").stop(false, true).hide().slideDown("fast");
},
close: function() {
$(this).tooltip("widget").stop(false, true).show().slideUp("fast");
}
}).tooltip("widget").addClass("ui-state-highlight");
}
}
});
$("#list").jqGrid('navGrid','#pager',{edit:false,add:false,del:false});
$("#list").jqGrid('filterToolbar', {stringResult: true, searchOnEnter: false,
defaultSearch: 'cn', ignoreCase: true});
});
and in the php file
$ops = array(
'eq'=>'=', //equal
'ne'=>'<>',//not equal
'lt'=>'<', //less than
'le'=>'<=',//less than or equal
'gt'=>'>', //greater than
'ge'=>'>=',//greater than or equal
'bw'=>'LIKE', //begins with
'bn'=>'NOT LIKE', //doesn't begin with
'in'=>'LIKE', //is in
'ni'=>'NOT LIKE', //is not in
'ew'=>'LIKE', //ends with
'en'=>'NOT LIKE', //doesn't end with
'cn'=>'LIKE', // contains
'nc'=>'NOT LIKE' //doesn't contain
);
function getWhereClause($col, $oper, $val){
global $ops;
if($oper == 'bw' || $oper == 'bn') $val .= '%';
if($oper == 'ew' || $oper == 'en' ) $val = '%'.$val;
if($oper == 'cn' || $oper == 'nc' || $oper == 'in' || $oper == 'ni') $val = '%'.$val.'%';
return " WHERE $col {$ops[$oper]} '$val' ";
}
$where = ""; //if there is no search request sent by jqgrid, $where should be empty
$searchField = isset($_GET['searchField']) ? $_GET['searchField'] : false;
$searchOper = isset($_GET['searchOper']) ? $_GET['searchOper']: false;
$searchString = isset($_GET['searchString']) ? $_GET['searchString'] : false;
if ($_GET['_search'] == 'true') {
$where = getWhereClause($searchField,$searchOper,$searchString);
}
I saw the query, and $searchField,$searchOper,$searchString have no value
But when I use the button search on the navigation bar it works! I dont konw what is happening with the toolbarfilter
Thank You
You use the option stringResult: true of the toolbarfilter. In the case the full filter will be encoded in filters option (see here). Additionally there are no ignoreCase option of toolbarfilter method. There are ignoreCase option of jqGrid, but it works only in case of local searching.
So you have to change the server code to use filters parameter or to remove stringResult: true option. The removing of stringResult: true could be probably the best way in your case because you have only one searchable column. In the case you will get one additional parameter on the server side: examen. For example if the user would type physic in the only searching field the parameter examen=physic will be send without of any information about the searching operation. If you would need to implement filter searching in more as one column and if you would use different searching operation in different columns you will have to implement searching by filters parameter.
UPDATED: I wanted to include some general remarks to the code which you posted. You will have bad performance because of the usage
$("#"+id+ " td:eq(1)", grid[0])
The problem is that the web browser create internally index of elements by id. So the code $("#"+id+ " td:eq(1)") can use the id index and will work quickly. On the other side if you use grid[0] as the context of jQuery operation the web browser will be unable to use the index in the case and the finding of the corresponding <td> element will be much more slowly in case of large number rows.
To write the most effective code you should remind, that jQuery is the wrapper of the DOM which represent the page elements. jQuery is designed to support common DOM interface. On the other side there are many helpful specific DOM method for different HTML elements. For example DOM of the <table> element contain very helpful rows property which is supported by all (even very old) web browsers. In the same way DOM of <tr> contains property cells which you can use directly. You can find more information about the subject here. In your case the only thing which you need to know is that jqGrid create additional hidden row as the first row only to have fixed width of the grid columns. So you can either just start the enumeration of the rows from the index 1 (skipping the index 0) or verify whether the class of every row is jqgrow. If you don't use subgrids or grouping you can use the following simple code which is equivalent your original code
loadComplete: function() {
var i, rows = this.rows, l = rows.length;
for (i = 1; i < l; i++) { // we skip the first dummy hidden row
$(rows[i].cells(1)).tooltip({
content: function(response) {
var rowData = grid.jqGrid('getRowData',this.parentNode.id);
return rowData.descripcion;
},
open: function() {
$(this).tooltip("widget").stop(false, true).hide().slideDown("fast");
},
close: function() {
$(this).tooltip("widget").stop(false, true).show().slideUp("fast");
}
}).tooltip("widget").addClass("ui-state-highlight");
}
}
I'm dev an app into titanium mobile in javascript.
The dynamic menu insert each new object(id,text,...., page) into a loop for (var x in tab).
with thoses items, specifics views are made.
var items = [];
var menuIconsItem = require('view/module/menuIconsItem');
for(var i in itemTab) {
var page = itemTab[i].page;
items[i] = new menuIconsItem(itemTab[i]);
menuFirstLine.add(items[i]);
(function(itemsEvent) {
itemsEvent.addEventListener('click', function() {
Ti.App.fireEvent('test' +i, {
id : i
});
})
})(items[i]);
}
on the other controller side, i only get the last id reference.
If i = 0 to 5, i only get the last reference. The rest is undefined.
How could i do please?
First you have to set id for your menuIconsItem, I am taking button an an example here.
items[i] = Titanium.UI.createButton({
id:"button_"+i,
_index: i
})
Then do this:
(function(itemsEvent) {
itemsEvent.addEventListener('click', function(e) {
alert(e.source.id);
})
})(items[i]);
I am writing a simple test app to experiment with the functionality of node.js and couchdb, so far i am loving it, but i ran in a snag. i have looked for and wide but can't seem to find an answer. My test server(a simple address book) does 2 things:
if the user goes to localhost:8000/{id} then my app returns the name and address of the user with that id.
if the user goes to localhost:8000/ then my app needs to return a list a names that are hyperlinks and takes them to the page localhost:8000/{id}.
I was able to get the first requirement working. i cant not seem to find how to retrieve a list of all names from my couchdb. that is what i need help with. here is my code:
var http = require('http');
var cradle = require('cradle');
var conn = new(cradle.Connection)();
var db = conn.database('users');
function getUserByID(id) {
var rv = "";
db.get(id, function(err,doc) {
rv = doc.name;
rv += " lives at " + doc.Address;
});
return rv;
}
function GetAllUsers() {
var rv = ""
return rv;
}
var server = http.createServer(function(req,res) {
res.writeHead(200, {'Content-Type':'text/plain'});
var rv = "" ;
var id = req.url.substr(1);
if (id != "")
rv = getUserByID(id);
else
rv = GetAllUsers();
res.end(rv);
});
server.listen(8000);
console.log("server is runnig");
As you can see, I need to fill in the GetAllUsers() function. Any help would be appreciated. Thanks in advance.
I would expect you to be doing something like (using nano, which is a library I authored):
var db = require('nano')('http://localhost:5984/my_db')
, per_page = 10
, params = {include_docs: true, limit: per_page, descending: true}
;
db.list(params, function(error,body,headers) {
console.log(body);
});
I'm not pretty sure what you are trying to accomplish with http over there but feel free to head to my blog if you are looking for some more examples. Just wrote a blog post for people getting started with node and couch
As said above it will come a time when you will need to create your own view. Check up the CouchDB API Wiki, then scan thru the book, check what are design documents, then if you like you can go and check the test code I have for view generation and querying.
You can create a CouchDB view which will list the users. Here are several resources on CouchDB views which you should read in order to get a bigger picture on this topic:
Introduction to CouchDB Views
Finding Your Data with Views
View Cookbook for SQL Jockeys
HTTP View API
So let's say you have documents structured like this:
{
"_id": generated by CouchDB,
"_rev": generated by CouchDB,
"type": "user",
"name": "Johny Bravo",
"isHyperlink": true
}
Then you can create a CouchDB view (the map part) which would look like this:
// view map function definition
function(doc) {
// first check if the doc has type and isHyperlink fields
if(doc.type && doc.isHyperlink) {
// now check if the type is user and isHyperlink is true (this can also inclided in the statement above)
if((doc.type === "user") && (doc.isHyperlink === true)) {
// if the above statements are correct then emit name as it's key and document as value (you can change what is emitted to whatever you want, this is just for example)
emit(doc.name, doc);
}
}
}
When a view is created you can query it from your node.js application:
// query a view
db.view('location of your view', function (err, res) {
// loop through each row returned by the view
res.forEach(function (row) {
// print out to console it's name and isHyperlink flag
console.log(row.name + " - " + row.isHyperlink);
});
});
This is just an example. First I would recommend to go through the resources above and learn the basics of CouchDB views and it's capabilities.