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October 24, 2016

MySQL about constraint

J.Doe’s Question:

Good afternoon,

Can anyone tell me what’s wrong with my code on PHP MY ADMIN, I’m trying to write a CONSTRAINT and create values for the car color in the beginning ( with table creation)

CREATE TABLE T_CAR
(CAR_ID                INTEGER       NOT NULL PRIMARY KEY,
 CAR_MARK            CHAR(32)      NOT NULL,
 CAR_MODEL            VARCHAR(16),
 CAR_NUMBER   CHAR(10)      NOT NULL,
 CAR_COLOR           CHAR(16)      CHECK (VALUE IN ('white', 'black', 'red', 'green', 'blue')))

The problem is with the last line (error message syntax not known).
Thanks in advance.

MySQL ignores check expression.

Manual: Create Table

The CHECK clause is parsed but ignored by all storage engines.

Try Enum:

CREATE TABLE T_CAR (
    CAR_ID INTEGER NOT NULL PRIMARY KEY,
    CAR_MARK CHAR(32) NOT NULL,
    CAR_MODEL VARCHAR(16),
    CAR_NUMBER CHAR(10) NOT NULL,
    CAR_COLOR ENUM('white', 'black', 'red', 'green', 'blue') NOT NULL
)
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October 20, 2016

How can I let a table cell take in the full width of the table with css?

Jim Peeters’s Question:

For some reason the cells in my second row in my table are changing the width of the cells in the row above. I have no idea why this is the cause. I don’t want the width of the first cell in the first row to be changed. I have reproduced the problem in jsfiddle to make it clear what I mean.

FiddleJS link:

https://jsfiddle.net/bpyrgsvc/1/

HTML:

<div class="table">
  <div class="row">
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
  </div>
  <div class="row">
    <div class="cell">this changes the width of the cell above</div>
  </div>
</div>

CSS:

.table {
  display:table;
}

.row {
  display: table-row;
}

.cell {
  display: table-cell;
  padding: 5px;
  border: 1px solid black;
}

I don’t see anything wrong with the results. In a div set to be displayed as table and table-row, it is behaving as tables.

To get the result you want, close the first table and start another.

<div class="table">
  <div class="row">
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
    <div class="cell">test</div>
  </div>
</div>
<div class="table">
  <div class="row">
    <div class="cell cell-full">this changes the width of the cell above</div>
  </div>
</div>

https://jsfiddle.net/bpyrgsvc/4/

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October 17, 2016

Change width of child div element using JQuery

Bodzilla’s Question:

I have an element in my html with this markup:

<div class="ui-accordion-content ui-helper-reset ui-widget-content ui-corner-bottom ui-accordion-content-active" role="tabpanel" style="width: 98px; display: block;">

I would like to know how to remove the width attribute using jQuery

You can set the width to be auto

$("selector").css('width', 'auto);
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September 20, 2016

How do I know when my docker mysql container is up and mysql is ready for taking queries?

Haren’s Question:

I am deploying a few different docker containers, mysql being the first one. I want to run scripts as soon as database is up and proceed to building other containers. The script has been failing because it was trying to run when the entrypoint script, which sets up mysql (from this official mysql container), was still running.


sudo docker run --name mysql -e MYSQL_ROOT_PASSWORD=MY_ROOT_PASS -p 3306:3306 -d mysql
[..] wait for mysql to be ready [..]
mysql -h 127.0.0.1 -P 3306 -u root --password=MY_ROOT_PASS < MY_SQL_SCRIPT.sql

Is there a way to wait for a signal of an entrypoiny mysql setup script finishing inside the docker container? Bash sleep seems like a suboptimal solution.

EDIT: Went for a bash script like this. Not the most elegant and kinda brute force but works like a charm. Maybe someone will find that useful.


OUTPUT="Can't connect"
while [[ $OUTPUT == *"Can't connect"* ]]
do
OUTPUT=$(mysql -h $APP_IP -P :$APP_PORT -u yyy --password=xxx < ./my_script.sql 2>&1)
done

On your ENTRYPOINT script, you have to check if you have a valid MySQL connection or not.

This solution does not require you to install a MySQL Client on the container and while running the container with php:7.0-fpm running nc was not an option, because it had to be installed as well. Also, checking if the port is open does not necessarily mean that the service is running and exposed correctly. [more of this]

So in this solution, I will show you how to run a PHP script to check if a MySQL Container is able to take connection. If you want to know why I think this is a better approach check my comment here.

File entrypoint.sh

#!/bin/bash
cat << EOF > /tmp/wait_for_mysql.php
<?php
$connected = false;
while(!$connected) {
    try{
        $dbh = new pdo( 
            'mysql:host=mysql:3306;dbname=db_name', 'db_user', 'db_pass',
            array(PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION)
        );
        $connected = true;
    }
    catch(PDOException $ex){
        error_log("Could not connect to MySQL");
        error_log($ex->getMessage());
        error_log("Waiting for MySQL Connection.");
        sleep(5);
    }
}
EOF
php /tmp/wait_for_mysql.php
# Rest of entry point bootstrapping

By running this, you are essentially blocking any bootstrapping logic of your container UNTIL you have a valid MySQL Connection.

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September 14, 2016

relative position and left and right property together not working, only left is working

Ua_boaz’s Question:

I am using this tree grid directive github.com, and below css is taken directly from this library.

.tree-grid .level-2 .indented {
    position : relative;
    left     : 20px;
}

<td><a ng-click="user_clicks_branch(row.branch)"><i ng-class="row.tree_icon" ng-click="row.branch.expanded = !row.branch.expanded" class="indented tree-icon"></i></a><span class="indented tree-label tree-grid-row level-2>
             Citi Corporate and Investment Banking</span>
            </td>

The problem i am having is that span inside td is overflow and showing in the next column, for that purpose i need to add right:20px, but it is not working.

Is there any solution to this problem
plnkr.co

Just adding padding-right: 20px; gives what you are asking.

I selected the targeted span from CSS like

<!DOCTYPE html>
<html ng-app="abas-web">
  ...
  <body>
  ...
  <style>
    span.indented.tree-label {
      padding-right: 20px;
    }
  </style>
  </body>

</html>

Demo

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June 30, 2016

How to run Witter app from Udacity “Offline Web Applications” course using docker?

This blog post shows how you can run the Wittr application from a Udacity course called ‘Offline Web Applications’ using docker. This is helpful if your development stack does not run on localhost and you want to overcome `insecure origin` issue of the browsers.

Note: This is blog post, so I have written a bit back story as well. If you don’t want to read about that clone https://github.com/starx/wittr.git run docker-compose up -d Done!

I was trying a course from udacity called “Offline Web Applications” and I got stuck in the point where I was trying to register the service worker. That was because the request to register the service worker was coming form an insecure origin. Nowadays, modern browser browswer have started to deprecate powerful web feature on insecure origin (more here)) and the course fails to address this issue because the developer’s stack can vary. So the question is What is secure origin?

In chrome “Secure origins” are origins that match at least one of the following (scheme, host, port) patterns: more here

(https, *, *)
(wss, *, *)
(*, localhost, *)
(*, 127/8, *)
(*, ::1/128, *)
(file, *, —)
(chrome-extension, *, —) 

So it still supports developer in a way that is does not restrict request from localhost 127... or ::1. Which was another thing to fix because my development stack is not be the most common one as I don’t use localhost to test my work. I do these through vms, vagrant and nowadays from docker as well. This means that most of the time the test url is anything but localhost. So stuck on this for a while I tries several things, like trying to turn off insecure origin flag on flag, proxy, trying to point localhost to another ip is windows 10 bunch of bullshit which is just lost time. So I created a docker configuration to run the witter project.

file: Dockerfile

FROM node:latest

# Create app directory
RUN mkdir -p /usr/src/app
WORKDIR /usr/src/app

# Install app dependencies
COPY ./* /usr/src/app/
RUN npm install

# Bundle app source
COPY . /usr/src/app

EXPOSE 8888 8889
CMD [ "npm run serve" ]

Simple enough for those who know docker basics. It binds with the ports in the host, so the project will run as localhost:8888 and localhost:8889 as the course wants. But if you want to know what it does, I am happy to explain it.

I have forked the course repo and have added this (with a docker-compose.yml as well) to the project itself at:

https://github.com/starx/wittr

Clone https://github.com/starx/wittr.git rather than the one provided in the course and run docker-compose up -d and continue with the course. I have also have created a pull request to help others but there is already 2 previous pull request pending without any comments, So I doubt it will be pulled.

Comments appreciated.

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June 8, 2016

How to restrict modification to selected properties of an entity while persisting?

Let’s suppose we have an entity class and a generic FormType corresponding to the entity

class Entry {
    protected $start_time;
    protected $end_time;
    protected $confirmed; // Boolean

    // ... Other fields and getters and setters
}

On the CRUD of this entity, you might not want to allow any modification on start_time or end_time if the entity has been confirmed or in the above case when $confirmed === true

Here are couple of ways this can be solved:

  1. Using the EntityManager you can retrieve original data of the entity. $em->getUnitOfWork()->getOriginalEntityData($entity) returns an array with old data of an entity which can be used to reset the data.

    if($form->isSubmitted() && $editForm->isValid()) {
        // The form was submitted
        if($confirmed === true) { // if the entity was confirmed previously
            $oldData = $em->getUnitOfWork()->getOriginalEntityData($entity);
            $entity->setStartTime($oldData['start_time']);
            $entity->setEndTime($oldData['end_time']);
        }
        // After this you can happily persist the data
        $em->persist($entity);
        $em->flush();
    }
    
  2. Using Form Events

    The following is a Symfony 3 Solution, try this solution for Symfony 2.

    class EntityType extends AbstractType
    {
        public function buildForm(FormBuilderInterface $builder, array $options)
        {
            // ....
            // ....
            // Your form fields
    
            $builder->addEventListener(FormEvents::POST_SET_DATA, array($this, 'onPreSetData'));
        }
    
    
        public function onPreSetData(FormEvent $event) {
            /** @var YourEntity $entity */
            $entity = $event->getData();
            $form = $event->getForm();
    
            if($entity instanceof YourEntity) {
                if ($entity->getTimesheetEntry()->getTimeApproved() === true) {
                    $config = $form->get('start_time')->getConfig();
                    $options = $config->getOptions();
                    $options['disabled'] = true;
                    $form->add('start_time', get_class($config->getType()->getInnerType()), $options);
    
                    $config = $form->get('end_time')->getConfig();
                    $options = $config->getOptions();
                    $options['disabled'] = true;
                    $form->add('end_time', get_class($config->getType()->getInnerType()), $options);
                }
            }
    
        }
    }
    
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April 8, 2016

javascript switch statement/case expression

RGdent’s Question:

I am using a switch statement to search for undefined values to manually change it. but I am having trouble using boolean expressions as I would when using an if statement.

Like: if statemant

if(Item1 == undefined)
{
  item1 ="No";
}
else if (Item2 == undefined)
{
  item2 = "No";
}

etc..

I tried this with the switch statement:

 switch (array) {
 case (item1 == undefined):
 item1 = "No";
 console.log('item1 result', item1 );
 break;
 case item2 == undefined:
 item2 = "No";
 console.log('item2 result', item2 );
 break;
 default:

 }

It does not run through the switch statement, except for when I remove == undefined and only use item1. then it works?

The switch cannot evaluate values of the array like that and that is why it does not run through the switch statement. You need to define which value of that array you want to switch.

Inside case statement you also cannot use expression, you have to use a value there as well.

So, if you are dead set on using switch for what you are trying to accomplish, you can do something like this:

item1 = array[1];
switch(item1) {
    case "undefined":
        // so on
    break;
}

But, based on your example you are probably trying to check if the values are set or not, for that if statements are still the best choice rather than switch.

$arr = []; // Your array
if(typeof $arr[0] == "undefined") {
    $arr[0] = "No";
}
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April 5, 2016

MVC Design – views with content for a usergroup

H0mebrewer’s Question:

I’m writing my first MVC application in PHP. I don’t want to use any framework.

Now I’m searching for a good solution or best practise to display elements for users in views, only if they are allowed to interact with the function that a specific element calls.

The app loads a template file in the view.
Within the template file I show the data from the model, which is passed from the controller to the view.

From controller

public function showUserList() {
    $userList = $this->model->getUserList();
    $this->view->loadTemplate($userList, 'user_list.php');
}

From view:

class user_view  {
    public function loadTemplate($data, $file, $buffer= false){
        if($buffer === true){
            ob_start();
            include dirname(__FILE__).'/templates/'.$file;
            $c = ob_get_contents();
            ob_end_clean();
            return $c;
        }else{
            include dirname(__FILE__).'/templates/'.$file;
        }
    }
}

Template:

<table class="table" id="data-table">
    <thead>
        <tr>
        <th>Name</th>
        <th>Username</th>
        <th>E-Mail</th>
        <th>Group</th>
        <th>Action</th>
        </tr>
    </thead>
    <tbody>
    <?php
       if(is_array($data)){

          foreach($data as $key => $value){
          ?>
            <tr>
                <td><?php echo $data['name'].' '.$data['surname']; ?></td>
                    <td><?php echo $data['abbr']; ?></td>
                    <td><?php echo $data['email']; ?></td>
                    <td><?php echo $data['gr_name']; ?></td>
                    <td>

                    <div data-access="," onclick="$user_controller.showUserChangeView('<?php echo $data['id']; ?>')" class="btn btn-primary">edit</div>
                    <div data-access="checkAccess" onclick="$user_controller.deleteUser('<?php echo $data['id']; ?>')" class="btn btn-danger">delete</div>

                    </td>
                </tr>

          <?php
          }

       }
    ?>
    </tbody>
</table>
</div>

I want to display buttons or menuitmes only, if a user is permitted to call the function of the button or the menuitem.

My first approach ist to create a template file with all elements which could be displayed. Elements which should not be accessible for all users get an data attribute.

The view loads the template, a DOM parser pareses the file, checks if the user is permitted to call that function with a data attribute.
If the user is not permitted to call that function, the element will be removed.
This is not yet implemented because I’m not sure if this is that a good solution or how I can do it even better?

My suggestion is to implement either ACL (Access Control List) or RBAC (Role Based Access Control) depending on what you find useful. I prefer RBAC so I will give a minimalistic example of one.

Create a list of all possible actions a user can make and define roles which might have acess to them.

// List of permissions (the actual term to define resources in RBAC) for the users
$actions = array(
    'view' => array(ROLE_USER, ROLE_OWNER, ROLE_MANAGER, ROLE_ADMIN),
    'edit' => array(ROLE_OWNER, ROLE_ADMIN),
    'delete' => array(ROLE_OWNER, ROLE_ADMIN),
    'change_pass' => array(ROLE_OWNER, ROLE_MANAGER, ROLE_ADMIN)
)

Now when you display the button for these actions, you can check if current user has any of the role which allows him to access the actions. If answer to that is “yes” then show them otherwise don’t show them at all.

$currentUserRole = '..'; //Retrieve however you want
foreach($actions as $allowed_roles) {
    if(in_array($currentUserRole, $allowed_roels)) {
        echo "<div ...>"; // Basically show the action
    }
    // If not carry on to next action with out showing
}

(Note: Not showing only might not be enough for it be secured, so we must also the check then when executing the action as well)

Update: You would the put the above code in the following part:

<table class="table" id="data-table">
    <thead>
        <tr>
        <th>Name</th>
        <th>Username</th>
        <th>E-Mail</th>
        <th>Group</th>
        <th>Action</th>
        </tr>
    </thead>
    <tbody>
    <?php
       if(is_array($data)){

          foreach($data as $key => $value){
          ?>
            <tr>
                <td><?php echo $data['name'].' '.$data['surname']; ?></td>
                    <td><?php echo $data['abbr']; ?></td>
                    <td><?php echo $data['email']; ?></td>
                    <td><?php echo $data['gr_name']; ?></td>
                    <td>
                        $currentUserRole = '..'; //Retrieve however you want
                        foreach($actions as $allowed_roles) {
                            if(in_array($currentUserRole, $allowed_roels)) {
                               echo "<div ...>"; // Basically show the action
                            }
                            // If not carry on to next action with out showing
                        }
                    </td>
                </tr>

          <?php
          }

       }
    ?>
    </tbody>
</table>
</div>
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