Day: January 3, 2016

what I assume is a pretty basic question here-

There are several flavors of questions regarding this error, but none in the first 5 results that have the added nuance of Spring.

I have the beginnings of a REST-ful webapp written in spring. I am trying to connect it to a database.

I have an entity named Workspace and am trying to use the spring injection of a bean( correct terminology ?) to save an instance of the workspace entity

package com.parrit;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.util.Assert;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

import com.parrit.models.Workspace;
import com.parrit.models.WorkspaceRepository;

@RestController
@RequestMapping("/workspace")
public class WorkspaceController {

    @Autowired
    private final WorkspaceRepository repository;

    @RequestMapping(method = RequestMethod.POST)
    void save( @RequestBody String workspaceHTML) {
        Workspace ws = new Workspace();
        ws.setHTML(workspaceHTML);
        repository.save(ws);
    }
}

My error is on the repository variable private final WorkspaceRepository repository. The compiler is complaining that it may not be initialized and attempting to run the app yields the same result.

How do I get an instance of this repository object into my controller in order to do save operations on it?

Answer

Having @Autowired and final on a field are contradictory.

The latter says: this variable has one and only one value, and it’s initialized at construction time.

The former says: Spring will construct the object, leaving this field as null (its default value). Then Spring will use reflection to initialize this field with a bean of type WorkspaceRepository.

If you want final fields autowired, use constructor injection, just like you would do if you did the injection by yourself:

@Autowired
public WorkspaceController(WorkspaceRepository repository) {
    this.repository = repository;
}

I have recently started using vim.I want to set up files having .jsx extension to be treated as .js java script file in Vim. Also I want to enable es-linting, snippets with my .jsx files. I have installed following packages in my system

npm install -g eslint
npm install -g babel-eslint
npm install -g eslint-plugin-react

I have also installed Bundle 'mxw/vim-jsx' to support jsx in vim.

Also added following lines in my .vimrc file

let g:syntastic_javascript_checkers = ['eslint']
let g:jsx_ext_required = 0

Edit Found this vim plugin for react snippets: Vim-react-snippets

Answer

I decided to write this tutorial to setup vim for React development in depth so that beginners find this useful when they start with vim and react.

Syntax highlighting

To get the jsx syntax high-lighting to look right in vim, use mxw’s Vim JSX plugin.

Steps to Install mxw/vim-jsx Plugin

If you use Vundle,

add following lines in your .vimrc:

Plugin 'mxw/vim-jsx'
Plugin 'pangloss/vim-javascript'

This plugin depends upon pangloss/vim-javascript so you need to install that as well.

To install from within vim, use the commands below.

:so ~/.vimrc

To source changed .vimrc configuration file and use it, next

:PluginInstall

If you use pathogen

cd ~/.vim/bundle
git clone https://github.com/mxw/vim-jsx.git

Enable JSX Syntax Highlighing in javascript files

Add following lines in your .vimrc:

let g:jsx_ext_required = 0 

Enabling eslint in vim

You need to install following helper npm packages along with latest eslint ( used 2.11.1 at the time of writing ). Also make sure that you have node.js version 4 or above installed in your system.

babel-eslint – To support ES6 linting

eslint-plugin-react – React specific linting rules for ESLint e.g prevent usage of setState in componentDidMount

npm install  --save-dev eslint
npm install --save-dev babel-eslint
npm install --save-dev eslint-plugin-react

I decided to use common practices and conventions used by AirBnB, so I installed following packages as well. But You don’t need them If you do not want to use AirBnB eslint presets.

npm install --save-dev eslint-config-airbnb
npm install --save-dev eslint-plugin-import
npm install --save-dev eslint-plugin-jsx-a11y

Create a config file .eslintrc.json in your project’s root: (You can use eslint to generate eslint configuration file in intreactive way)

eslint --init

(If you chose any presets make sure you also install required package for that lint preset)

I extended “airbnb” but overrided some of rules for my project. You can use “extends”: “eslint:recommended” to enable some common lint rule recommended by eslint Here is my .eslintrc.json file

{
    "extends"       : "airbnb",
    "parser"        : "babel-eslint",
    "parserOptions" : {
        "ecmaVersion"  : 6,
        "sourceType"   : "module",
        "ecmaFeatures" : {
            "jsx":true
        }
    },
    "env": {
        "browser" : true,
        "node"    : true,
        "jquery"  : true
    },
    "settings":{
        "react":{
            "pragma":"React",
            "version":"15.1.0"
        },
        "ecmascript":6,
        "jsx":true
    },
    "plugins": [
        "react"
    ],
    "rules": {
        "strict": 0,
        "quotes": 0,
        "no-unused-vars": 1,
        "camelcase": 1,
        "no-underscore-dangle": 1,
        "comma-dangle":[1,"never"],
        "indent":["error",4],
        "react/jsx-indent":0,
        "react/jsx-equals-spacing": [2, "always"],
        "no-console":0,
        "max-len":1,
        "no-param-reassign":1,
        "key-spacing": [
              2,
              {
                "align": "colon",
                "beforeColon": true,
                "afterColon": true
              }
        ],
        "no-multi-spaces": [
              2,
              {
                "exceptions":{
                    "VariableDeclarator":true,
                    "ImportDeclaration":true,
                    "JSXAttribute":true,
                    "AssignmentExpression":true
                }
              }
        ]
    }
}

Now integrate ESLint with Syntastic Plugin in Vim I decided to use Syntastic with vim for syntax error checking.

let g:syntastic_javascript_checkers = ['eslint']

All set but still there is one issue remaining with Syntastic. Syntastic searches global node_modules instead of local project.

One solution will be install all packages eslint, babel-eslint etc globally which definately will not be a good practice.

Another solution is

Define a npm script in your package.json

"eslint": "eslint -c .eslintrc.json"

It will add all the locally installed npm packages in current path, so they will be available for execution.

And in your .vimrc file add

let g:syntastic_javascript_eslint_exe = 'npm run eslint --'

Here we are invoking linting via npm script from vim.

Alternative: use Plug ‘mtscout6/syntastic-local-eslint.vim’ plugin

Open error window in vim as you open your file –

Add following lines to your .vimrc to show current lint error (in case any) as you open your file for edit

let g:syntastic_always_populate_loc_list = 1
let g:syntastic_auto_loc_list = 1
let g:syntastic_check_on_open = 1
let g:syntastic_check_on_wq = 0

Snipptes and auto-completion

There are different forks of snippet engines which allow the user to insert snippets by typing the name of a snippet hitting the expansion mapping.

• github.com/SirVer/ultisnips: python, supports all snippets in this repo.
• github.com/garbas/vim-snipmate: VimL, snipmate-snippets, engine sometimes behaves strange. Supports snippets/*
• github.com/Shougo/neosnippet: VimL, supports snippets/* with some configuration.
• github.com/drmingdrmer/xptemplate: Totally different syntax, does not read snippets contained in this file, but it is also very powerful.

I prefer neosnippet. Install it in your vim, to enable snippets with neocomplete for auto-completion.

Neocomplete is an amazing autocomplete plugin with additional support for snippets. It can complete simulatiously from the dictionary, buffer, omnicomplete and snippets. This is the one true plugin that brings Vim autocomplete on par with the best editors.

See install instructions here for neocomplete

After installing above plugins you need to install one more plugin to enable react specific snippets

Bundle 'justinj/vim-react-snippets'

See install instructions here for that plugin.

If all setup done correctly, you have enabled vim with eslinting, auto completions, JSX syntax hightlighting for React, with ES6 features !

Taken from my blog post.

I am trying to do a JSONObject request:

final String URL = "https://some/url";

// Post params to be sent to the server
HashMap<String, String> params = new HashMap<String, String>();
params.put("param1", param1);

params.put("param2", param2);

params.put("param3", param3);
    
params.put("param4", param4);


JsonObjectRequest req = new JsonObjectRequest(URL, new JSONObject(params), new Response.Listener<JSONObject>() {
    @Override
    public void onResponse(JSONObject response) {
        try {
            VolleyLog.v("Response:%n %s", "läuft");
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
        VolleyLog.e("Error: ", error.getMessage());
    }
});

// add the request object to the queue to be executed
NetworkController.getInstance().addToRequestQueue(req);

I cannot compile the project because I get a syntax error for the params:

Error:(144, 9) error: illegal character: ‘u2028’

How can I fix that?

Answer

Well, just deleting all the characters and rewriting them again helped. So crazy..

I have a presentation slide in speakerdeck and i want to embed it in README.md page of github repository. is it possible to do so?

Here is my embedded script from speakerdeck

<script async class="speakerdeck-embed" data-id="3586d5e7f45ce6" data-ratio="1.33333333333333" src="//speakerdeck.com/assets/embed.js"></script>

README.md

###Introduction

This is a introduction of the app …

###Slide

<script async class="speakerdeck-embed" data-id="3586d6f45ce6"
data-ratio="1.33333333333333"
src="//speakerdeck.com/assets/embed.js"></script>

slide does not appear on README section of repo.

Answer

No, you can’t and you shouldn’t mostly because of security reasons.

GitHub won’t allow the execution of an external script.

Check this answer: Embed JavaScript in GitHub README.md

What is the best way to re-export a default export from another file?

I’d like to do something like this:

export Button from './Button/Button';

Apparently this is not valid EcmaScript syntax (however it used to work in older Babel versions).

As a result I want to import {Button} from 'components';

Is there a better way, maybe a one-liner? ES6 syntax would be preffered.

Thanks!

Answer

You can use the export { x as y } syntax:

export { default as Button } from './Button/Button';

I’d like to do something like this:

export Button from './Button/Button';

There is a stage 1 proposal for this syntax: https://github.com/leebyron/ecmascript-more-export-from