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Robbie Chipka edited this page Nov 16, 2015 · 177 revisions

##Command reference

These are all of the "commands" that are available for chaining in an Osmosis instance.

##config

#####( opts ) Set HTTP options and configure Osmosis

##data

#####( callback( data ) ) Calls callback with the current data object

#####( null ) Empty the data object

#####( object ) Add or replace each key in the data object with a new val

##debug

#####( callback( msg ) ) Call callback when any debug messages are received

##doc

Reset the current context to the Document

##dom

#####( callback ) Create a DOM object from the current context.

The callback will be be called with 3 arguments (window, data, and next). The next([context], [data]) function must be called at least once

##done

#####( callback ) Calls callback when parsing has completely finished

##error

#####( callback( msg ) ) Call callback when any error messages are received

##find

#####( selector ) Find elements based on selector anywhere within the current document

##follow

#####( [selector] ) Follow URLs found via selector. If selector isn't provided, follow will search the current element text or common URL attributes (href, src, etc).

####Examples:





.follow()
.follow('@href')
.follow('a')
.follow('a@href')
.follow('span.outlink')
.follow('input.cloneURL@value')
.follow('link[type="application/rss+xml"]@href')








##get / post




#####( url , [data] , [opts] , [callback] )
Make an HTTP request


url - A string containing a URL, which can be relative to the current context.


data (optional) - An object containing GET query parameters or POST request data.


opts (optional) - An object containing HTTP request options.


callback (optional) - A function called after making the request.
Just like .then, the callback function should have 3 arguments (context, data, next) and must call next at least once.




Note: Query parameter values will be urlencoded by needle so make sure that your parameter values are not urlencoded.




##log




#####( callback( msg ) )
Call callback when any log messages are received




##login




#####( user , pass , [success] , [fail] )
Submit a login form.


#####Arguments:
user - A string containing a username, email address, etc.


pass - A password string


success (optional) - A selector string determining if the login attempt succeeded


fail (optional) - A selector string determining if the login attempt failed




######How it works
login finds the first form containing input[type="password"] and uses that input as the password field. It will use the preceding <input> element as the user field.




##page / paginate




#####( selector , [limit] )
Paginate the previous request limit times based on selector.


####selector:
selector (String) - A selector string for either:


    

  • an element with the next page URL in its inner text or in an attribute that commonly contains a URL (href, src, etc.)
    • 

  • an element whose name and value attributes will respectively be added or replaced in the next page query.
    • 



selector (Object) - An object where each key is a query parameter name and each value is either a selector string or an increment amount (+1, -1, etc.).


####limit:
limit (Number) - Total number of "next page" requests to make.


limit (String) - A selector string for an element containing the total number of requests to make.




.paginate('a.nextPage') // go to `a.nextPage` `@href`
.paginate('link[rel="next"]@href') // go to `link` `@href`
.paginate('input[name="page"]') // update `page` parameter of the next query

// adds 20 to the `startIndex` query parameter
// sets `page` query parameter to `a.nextPage` content
// stops after 15 requests are made
.paginate({ startIndex: +20,  page: 'a.nextPage' }, 15)




##pause / resume / stop




Pause, resume or stop an osmosis instance.




##parse




#####( string )
Parse an HTML or XML string


#####Arguments:
string - A string or buffer containing the HTML/XML data




##set




#####( name , selector)
Set name to the value of selector


#####( object )
Set each key to the value of each val selector.








.set('title') // set 'title' to current element text
.set('title', 'a.title') // set 'title' to text of 'a.title'
.set({
title:  'a.title',
description: 'p.description',
url: 'a.permalink @href',
images: ['img @src'],
comments: [
osmosis
.follow('a.comments')
.find('div.comment')
.set({
'author': '.author'
'content': 'p.content',
'date': '.date'
})
]
});








##submit




#####( selector , [data] )
Submit a form


#####Arguments:
selector - A selector for the <form> element


data (optional) - An object where each key and value represents a form input name and value




##then




#####( callback( context, data, [next], [done] ) )
Calls callback with the context of the current element.


####context:
The context argument is the current context at that point in the command chain. If the previous command was get, post, follow, or parse then the context will be a Document. If the previous command was find then the current context will be one of the Elements that was found.


####data:
The data argument contains values set via osmosis.set. This object can be modified in any way.


####next:
The next argument is a function that will call the next command. It takes two arguments: context and data.


####done:
The done argument is a function to call when then will no longer call next.
This is only required if then calls next asynchronously any number of times.
Note: If the then callback accepts done as an argument, it must always call done,
even if next was never called.


####Functions
The callback will have these functions bound to its this value:


    

  • this.request(method, url, [data], callback([err], context), [opts])
    • 

  • this.log(msg)
    • 

  • this.debug(msg)
    • 

  • this.error(msg)
    • 



####Properties
The callback will have these properties:


    

  • this.instance - The Osmosis instance number that this command is in.
    • 

  • this.depth - The current position in the command chain.
    • 

  • this.next - The next command in the chain. Note that the next() argument is really just a shortcut for this.next.start()

    • 

  • this.prev - The previous command in the command chain.
    • 



####Examples:


Example 1: find every ul > li and pass it to the next command






osmosis
...
.then(function(context, data, next) {
var items = context.find('ul > li');
items.forEach(function(item) {
next(item, data);
})
})





**Example 2:** set `data.url` to the current page URL
```javascript





osmosis
...
.then(function(context, data, next) {
data.url = context.doc().request.url;
next(context, data);
})





**Example 3:** only continue if `lastname != undefined`
```javascript





osmosis
...
.then(function(context, data, next) {
if (data.lastname != undefined)
next(context, data)
})





**Example 4:** using the `done` function
```javascript





osmosis
...
.then(function(context, data, next, done) {
if (db.connected == false) {
this.error('database disconnected');
done();
return;
}
data.someArray.forEach(function(obj, index) {
db.save(obj, function() {
next(context, data);
if (index == data.someArray.length-1)
dane();
})
})
})








              


              

                
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