I am new to meteor and learning to create web application looking at examples. I want to append the updated values of the database to html textarea.
For example if i update value for key "sensor", the sensor value needs to be appended to textarea. How can I do that using meteor?
You use a handlebars helper and bind changes to your text area to update the field: e.g
html
<template name="hello">
<textarea name="address">{{address}}</textarea>
</template
client side js
//Your collection that stores your data
MyCollection = new Meteor.Collection("mycollection");
//Your handlebars helper to give some data to address
Template.hello.address = function() {
var address = MyCollection.findOne({name:address});
if(address) return address.value;
}
//Something to bind changes to your address to your collection
Template.hello.events({
'change [name=address]' : function(e,cxt) {
var address = MyCollection.findOne({name:address});
MyCollection.update(address._id, {$set:{value:e.currentTarget.value}});
}
});
Finally you need something on your server side js too:
//The same collection as on your client
MyCollection = new Meteor.Collection("mycollection");
//Insert an address on the first time if there is nothing in yet:
Meteor.startup(function() {
if(!MyCollection.findOne({name:address})) {
MyCollection.insert({name:address,value:"10 Downing St, London, United Kingdom"});
}
});
Thats the basic gist of it to update a text area when its changed, and to show a value in your template . When its updated it will also reflect the update across to all tabs/everyone viewing the page.
Related
I have something like this:
Template.todoList.helpers({
todos: function() {
return Todos.find({}); // Returns records with a todoText, ownerId and done field.
}
});
And then in the template I use a {{#each}} block to list the todos. But I want to be able to change if they are done with a checkbox. If I just add a checkbox like this in the {{#each}} block, it will correctly display the initial state, but if I toggle the checkbox, the record will not update. I would need to keep track of the _id of the record, but where would I store it? If I can get hold of the correct _id the rest is very simple:
Template.todoList.events({
'change .doneCheckbox': function(event) {
var todoId = ??;
Todos.update(todoId, {$set: {done:event.target.checked}});
}
});
What would I insert at the place of ???
Should be available from this (more specifically this._id):
var todo = this,
todoID = todo._id;
You can access other properties from the record too (e.g. this.done).
I am struggling to figure out the basic pattern for populating a template with data from a call to an external API in Meteor.
These are the elements in play
A fresh Meteor project, created by running meteor create monkeyproject
The URL of an external API that returns a JSON array. Let's say it's example.com/api/getmonkeys. It returns an array of monkeys, each with a different name.
A Handlebar template called monkeyTemplate with an {{#each}} loop. Let's say it's this:
<template name="monkeyTemplate">
{{# each monkeys}}
One of our monkeys is named {{name}}. <br>
{{/each}}
<input type="button" id="reload" value="Reload monkeys" />
</template>
What I want to happen
When the page loads fill monkeyTemplate with monkeys from our external URL.
When the user clicks the button, call the external URL again to reload the monkeys.
The question
What is a standard pattern for doing the above in Meteor? At the risk of cluttering up the question, I'll include some starting points, as I understand them.
We can populate the template with whatever we return from our Template.monkeyTemplate.monkeys function. How do we fill it with content from an external URL, given that the page will load before the external request is finished?
We can get our JSON by using Meteor.HTTP.call("GET", "http://example.com/api/getmonkeys", callback ). Where do we put this request, and what do we put into our callback function in this situation?
We can control what happens on the server side and what happens on the client side by using the Meteor.isServer/Meteor.isClient conditions, or by putting our code into files called client and server folders. What code needs to be on the server side vs. the client side?
We determine what happens when the button is clicked by attaching a function to Template.monkeyTemplate.events['click #reload']. What goes into our callback function in this situation?
I will refrain from cluttering up the question with my crappy code. I am not looking for anyone to write or rewrite an application for me—I am just looking for the guidelines, standard patterns, best practices, and gotchas. Hopefully this will be instructive to other beginners as well.
I'm not sure if this is the "standard" template, but it serves the purpose pretty well.
Set up two data helpers for the template, monkeys and loading. First one will display the actual data once it's fetched, the latter will be responsible for notifying user that the data is not yet fetched.
Set up a dependency for these helpers.
In created function of the template, set loading helper to true and fetch the data with HTTP call.
In the callback, set the template data and fire the dependency.
html
<template name="monkeys">
{{#if loading}}
<div>Loading...</div>
{{/if}}
{{#if error}}
<div>Error!</div>
{{/if}}
{{#each monkeys}}
<div>{{name}}</div>
{{/each}}
<div><button class="monkeys-reloadMonkeys">Reload</button></div>
</template>
js
var array = null;
var dep = new Deps.Dependency();
Template.monkeys.created = function() {
reloadMonkeys();
};
Template.monkeys.events({
'click .monkeys-reloadButton': function(e,t) {
reloadMonkeys();
};
});
var reloadMonkeys = function() {
array = null;
dep.changed();
HTTP.get('http://example.com/api/getmonkeys', function(error, result) {
if(!error && result) {
array = result;
} else {
array = 0;
}
dep.changed();
});
};
Template.monkeys.monkeys = function() {
dep.depend();
return array ? array : [];
};
Template.monkeys.loading = function() {
dep.depend();
return array === null;
};
Template.monkeys.error = function() {
dep.depend();
return array === 0;
};
Below I have a basic template that has a numerical input form. When you type a number in the form and click Add a list of Divs get created. The Divs are created with a class of "synth" and an id of "synth" + a number. The numbers go in succession based on a counter.
I want to not only store this information in the database but do so in a manner that (eventually) when a user logs in they will have access to their list of Divs as a "saved state" from their previous log in.
I am not even sure if I am going about this in an appropriate manner. I am simply sticking the createSynth() function in the Collection insert for lists. I have a feeling to do this "correctly" I should have two events that work in parallel - one sending to the lists Collection and the other to the dom/Template. These two blocks would then exchange data (some how) which in conjunction create the illusion of a "saved state".
Below is the code I have thus far.
HTML
<head>
<title></title>
</head>
<body>
{{> start}}
</body>
<template name="start">
<input id ="amount" type ="number" />
<input id ="submit" type="button" value="Add" />
<div id="applicationArea"></div>
</template>
Javascript
var lists = new Meteor.Collection("Lists");
var counter = 0;
counterSynth = 0;
if (Meteor.isClient) {
'use strict';
Template.start.events({
'mousedown #submit' : function () {
var amount = document.getElementById("amount").value;
for(i=0;i<amount;i++) {
lists.insert({SoundCircle:createSynth()}); // I am inserting the entire function call, is this the right path?
}
function createSynth() {
var synth = document.createElement("div");
synth.className = "synth";
synth.id = "synth" + (counterSynth++);
applicationArea.appendChild(synth);
};
},
});
}
if (Meteor.isServer) {
Meteor.startup(function () {
// code to run on server at startup
});
}
You have to use a slightly different approach to this, basically just insert your stuff into the collection, and use handlebars to get it out. I'm not entirely sure what you were doing but you should get a good idea with the below
Server js
synths = new Meteor.Collection('synths'); //This will store our synths
Client js:
synths = new Meteor.Collection('synths'); //This will store our synths
Template.start.events({
'mousedown #submit' : function () {
var amount = document.getElementById("amount").value;
for(i=0;i<amount;i++) {
lists.insert({class:"synth", id:counterSynth});
}
},
});
Template.start.synth = function() {
return synths.find(); //This gives data to the html below
}
HTML:
{{#each synth}}
<div class="{{class}}" id="synth{{id}}">
Synth stuff here
</div>
{{/each}
It's probably best to dynamically recreate the DIVs every time you need them on the client, so the DIV is not stored on the server. If you really want to hard code/store the DIV on the server you would need to simply save the HTML as a string, to a Meteor collection.
Ok so I'm not sure why I can't render the code. First if I console.log users.content I get the content I want but I'm some how not able to pass it to a textarea so that it show's it...
Users = new Meteor.Collection("users");
if(Meteor.is_client){
Template.inputUser.code = function(){
var el = Users.find({name:"oscar"});
el.forEach(function(users){
console.log(users.content);
})
}
}
And then on my html template I have
<body>{{> inputUser}}</body>
<template name="inputUser">
<textarea>{{content}}</textarea>
</template>
And I would have a record on the db suck as so
if(Meteor.is_server)
Users.insert({name:"oscar",content:"hello world"})
Thanks for your help guys.
Firstly your method Template.inputUser.code should return something, you should also note that it wouldn't be called with that template either as it needs a {{code}} call in it rather than {{content}}
The second point is database contents are not always available if you have disabled the autopublish package, if so check out using publish(in the server code) and subscribe(in the client code): http://docs.meteor.com/#meteor_subscribe you can use this to check when the client has all the data to display. Something like:
Meteor.subscribe('allusers', function() {
Template.inputUser.code = function(){
var user = Users.findOne({name:"oscar"});
return user.content;
}
});
...
Meteor.publish('allusers', function() {
return Users.find();
});
I'm very new to meteor, so apologies if I'm missing something very basic here.
I thought it would be fun to create a very simple textpad style app to check out meteor. I took the todo app and changed the data structures to be 'folders' and 'docs' rather than 'lists' and 'todos', so I have a list of folders and when you click on the folder you get a list of the documents in that folder.
I've then added some code to show the 'content' attribute of a single 'doc' when one of the docs in the list is clicked.
I'm using ace to add some pretty print to the content of the doc (https://github.com/ajaxorg/ace). I've set ace up to work with a hidden textarea containing the plaintext version of my document, and the editor object takes this text and pretty prints it.
The problem with ace is that I don't want the template containing the ace editor to be replaced every time the contents of the doc changes (as it takes half a second to reinitialise, which is a crappy experience after every character is typed!). Instead, I want to update the textarea template and then use the ace API to tell the editor to update it's input based on what is in the textarea.
Now, this is probably the wrong way to approach the problem, but I've ended up using two templates. The first contains a textarea containing doc.contents, which is reactive to the underlying model:
<template name="doc_content">
<textarea name="editor">{{content}}</textarea>
</template>
The second one contains the 'editor' div which ace uses to display the pretty printed text.
<template name="doc_init">
<div id="editor"></div>
</template>
The idea is that the first template will update every time the user types (on all clients), and the second template is only ever re-loaded for each new doc we load.
Template.doc_content.content = function() {
var doc_id = Session.get('viewing_itemname');
if (!doc_id) {
return {};
}
var doc = Docs.findOne({_id:doc_id});
if (doc && doc.content) {
// #1 Later
var editor = Session.get('editor');
if (editor) {
editor.getSession().setValue(doc.content);
}
return doc.content;
} else {
return '';
}
};
When you enter text into the editor div I make a call to Docs.update(doc_id, {$set: {content: text}});, which updates the value in the textarea on each client. All good so far.
editor.getSession().on('change', function(){
var text = editor.getSession().getValue();
Docs.update(doc_id, {$set: {content: text}});
});
What I want to do, for all clients other than the client which made the change, is to subscribe to the change for that doc and call editor.getSession().setContent() with the text which has just been changed, taking the text from the textarea and using it to fill the editor.
I've tried to do this by making that call from the template containing the textarea (as this changes whenever the doc is updated - see #1 above). However, this puts the clients into an infinite loop because changing the value in the editor causes another call to Docs.update.
Obviously this doesn't happen when you render a template, so I'm assuming there's some magic in meteor which can prevent this happening, but I'm not sure how.
Any thoughts?
TIA!
There's a lot to absorb in your question, but if I understand correctly, you might simply be after Deps.autorun:
Deps.autorun(function () {
var doc_id = Session.get('viewing_itemname');
if (!doc_id) {
return {};
}
var doc = Docs.findOne({_id:doc_id});
// do stuff with doc
});
Deps.autorun is really useful in that it will get re-run if any of its
dependencies change. These dependencies are limited to those that are "reactive"
such as Collections and Sessions, or anything that implements the reactive API.
In your case, both Session.get and findOne are reactive so if their values
change at all, Deps.autorun will run the function again.