When we use core-localstorage
<core-localstorage name="my-app-storage" value="{{value}}"></core-localstorage>
where it actually store the data? In some file on the HDD? What is the path?
LocalStorage is one of some ways you can store data in the client end in the Hard-drive, different browsers use different locations to save this file.
LocalStraoge makes use of JSON to store information worth up to 10MB(Might differ from browsers).
Usually, storing and retrieving from Local-storage is done through JavaScript but Polymer team has made a custom element you can use to make this process more Declarative.
Using the core-localstorage element:
<core-localstorage name="HOW YOU ACCESS THIS DATA" value="{{THE ACTUAL DATA YOU WANT TO STORE}}"></core-localstorage>
name attribute is how you access this data, every peice of data you store has to have a name with which you can set or get it's value through.
value attribute is the actual data you want to store, it can be an array, object, number or a string.
More documentations about core-localstorage and localstorage can be found at:
https://www.polymer-project.org/0.5/docs/elements/core-localstorage.html
http://diveintohtml5.info/storage.html
Related
I need to store the values of devices' attributes with the right type in OrionCB's MongoDB.
As I was unable to perform that I dived into the code and found that IoTAgentUL (as well as IoTAgentJSON) uses OrionCB's API v1 instead of API v2.
As I can see API v1's updateContext sends data to MongoDB without it's type, so every measure is stored as text.
In the other hand I found that API v2's update entity send data to MongoDB with it's type. It produces that I can store attribute's values with it's type which benefits me when manipulating data (i.e. creating indexes, sorting, etc).
My question is if is there any workaround to solve this using the current implementations of IoT Agents.
The only workaround I can imagine is, once entities are automatically created by the IoT Agents, to update the type of such entities by your own. I mean, AFAIK, you can update both the value and the type of an entity.
In more details, I can think on a script that subscribes for all entities of certain type (those created by the agents). Then, when an entity is created this is notified to the script, which automatically updates the type of the entity's attributes.
Please observe you only need to modify the attribute's types once, just when the entities are created, not when an entity's attribute is updated; thus, something like an array or cache of already modified entities is needed in your script.
We have a nested JSON structure in our web app on the frontend like Rows > Columns > Elements > Rows > Columns > Elements ...
We also have an API call which sends the entire data as JSON to backend.
In the backend we have a set of several permissions, like column size change, row background change, element ordering change, etc that are permitted or denied for various types of users.
We want to identify in the backend if the change of the nested structure is permissible.
Example 1 [Update data]:
The user has CHANGED the size of a 'Column', where the size is represented as a property in 'Column' object.
or
Example 2 [Remove/Add data]:
The user has removed/added an 'Element' from a 'Column'.
We know that we can do full traverse on the entire tree, and understand if the change was permissible or not, but we are looking for a better and faster, resource saving solution for concurrent connections and many users/big trees.
This question seems to be general for different technologies, but I want to let you know that we are using Laravel / Lumen / Dingo in the backend & Ember.js on the frontend.
Thanks for reading and helping :)
One option is to not send the entire JSON to the server, but to instead send json patch (see http://jsonpatch.com/). Then on the server, have rules that affectively hash the paths in the patch to permissions. In other words, since you are only sending the change and not the entire JSON, the need to parse the entir
You can have a API for returning permissions (have model Permission).
Then check for that permission for any actions you need in frontend by using ember-can.
By this, you can ensure that when you send back data for updating from front to back, it is complying the permissions defined in backend and no need for many back n forth
I think you can have type for each change. For example column change is ----> colChange(or simpleChange). Send the type of change with json. Permission can be checked by change type. Also there can be groups of change types and permission can be sat to groups. In case if you don't send data for each change there must be stack of user changes(push type of change into stack on each user change). Send that stack with json to backend .
We want to send some events to Application Insights with data showing which features a user owns, and are available for the session. These are variable, and the list of items will probably grow/change as we continue deploying updates. Currently we do this by building a list of properties dynamically at start-up, with values of Available/True.
Since AI fromats each event data as JSON, we thought it would be interesting to send through custom data as JSON so it can be processed in a similar fashion. Having tried to send data as JSON though, we bumped into an issue where AI seems to send through escape characters in the strings:
Eg. if we send a property through with JSON like:
{"Property":[{"Value1"},..]}
It gets saved in AI as:
{\"Property\":[{\"Value1\"},..]} ).
Has anyone successfully sent custom JSON to AI, or is the platform specifically trying to safeguard against such usage? In our case, where we parse the data out in Power BI, it would simplify and speed up a lot some queries by being able to send a JSON array.
AI treats custom properties as strings, you'd have to stringify any json you want to send (and keep it under the length limit for custom property sizes), and then re-parse it on the other side.
Here's my question: How might I try to get rid of the 'skipping precaching' and cache everything that comes in from https://laoadventist.info/beta/r as the precache list?
Also, is it correct for me to set precache="https://laoadventist.info/beta/r" or should I be setting that to a function that grabs the data and returns it instead?
Skipping precaching: Cannot read property 'concat' of null
comes out on the console when using My Polymer App
<platinum-sw-cache default-cache-strategy="fastest" cache-config-file="cache-config.json" precache="https://laoadventist.info/beta/r">
I am assuming correctly I can precahce a URL like this, right?
I am trying to load a json result from laravel 5.1 to set what my precache should be... I know it's not the most elegant, but I'm new to Polymer, cache, service workers, etc, and using this app as a learning opportunity. It'll be a bit different at the end of the day, but for now I just want to load everything. :)
I want to precache all of the data so that a user can fully utilize this app when offline (though later I'll set it up so that they don't have to precache loads and loads of json requests, only the ones they want, like per book - but that's for later).
If you have a array of resource URLs that you want precached, the cleanest way to specify them is to use the cacheConfigFile option and to point to a JSON file that contains your array as its precache property. Take a look at the example in the docs for cacheConfigFile: https://elements.polymer-project.org/elements/platinum-sw?active=platinum-sw-cache
You shouldn't have to use the precache attribute on the element if you're using cacheConfigFile.
It sounds like you're using Polymer Starter Kit, and that will create the JSON config file and populate it for you with an array corresponding to your local resources. But if you'd like to specify additional resources to be precached, you can modify the build process to append those URLs to the auto-generated list.
The reason you're seeing that error is because you're pointing to a JSON config file that is effectively empty, and is just meant for the development environment.
How can I use HTML5 local storage to save a little exe file and then download it by clicking the button?
Localstorage as you think is not a DataBase or even the File System, it's just some plain JSON files that store tiny bits of data in key: value pairs.
If you have worked with JSON before this will be very easy to grasp the Idea behind it.
Below is an example of setting and retrieving values from Local-storage:
locastorage.setItem('KEY',JSON.stringify('VALUE'));
// KEY is kind of like the variable name and the VALUE is the actual Data
JSON.parse(locastorage.getItem('KEY'));
// You use the KEY to access the value
// Using JSON methods stringify and parse just to be on the safer side.
HTML5 Localstorage is not for files.
Have a look at Mozilla's documentation here: https://developer.mozilla.org/en-US/docs/Web/API/Storage/LocalStorage
Instead it's for key/value pairs.
// Save data to the current local store
localStorage.setItem("username", "John");
// Access some stored data
alert( "username = " + localStorage.getItem("username"));
To start a download, you may want to look at a question like Download File Using Javascript/jQuery