Defensive Coding

Clean Code:

• Easy to read
• Sample
• Minimal
• Thoughtful

Verify and Coding contract

• Parameters
• Data
• Return Type
• Exception

Clean, Testable, Predictable Methods:

• Good Name
• Focused Code
• Short
• Exception

 

How to make webpack working together with Angular4

The official demo for Angualr 4 is using angular CLI to create project and run it. This approach is not friendly If you want to create a web application has .NET or Node.js as server side and Angualr 4 as client side.

Iet’s take a look inside the project created by angular CLI.

package.json : determain the library needed.
tsconfig.json : ts compiling
tslint.json : syntax checking
.angular-cli.json

 

 

 

 

 

I create a Node.js project and copy the content of those config files. And follow the document WEBPACK: AN INTRODUCTION [https://angular.io/docs/ts/latest/guide/webpack.html] to create webpack config file.

The key point is how to setup typescript:
“lib”: [ “es2016”, “dom” ]

I used webpack to compile and bundle all of the client side code into client_dist and reference them in the tempalte of Node.js

The project can be found at https://github.com/benjaminhuanghuang/nodejs-ng4-seed

Flask+AngularJS Http Post Download file

1. Download csv file

Server Side:

@userprogressreport.route(‘/filedownload’, methods=[‘POST’])
def filedownload():
csv = “”””REVIEW_DATE”,”AUTHOR”,”ISBN”,”DISCOUNTED_PRICE”
“1985/01/21″,”Douglas Adams”,0345391802,5.95
“1990/01/12″,”Douglas Hofstadter”,0465026567,9.95
“1998/07/15”,”Timothy “”The Parser”” Campbell”,0968411304,18.99
“1999/12/03″,”Richard Friedman”,0060630353,5.95
“2004/10/04″,”Randel Helms”,0879755725,4.50″””
file_name = “a.csv”
response = make_response(csv)
# This is the key: Set the right header for the response
# to be downloaded, instead of just printed on the browser
response.headers[“Content-Disposition”] = “attachment; filename=”+file_name
return response

Client Side:

$scope.exportUserProgressData = function () {
var params = $scope.getQueryParameter();

$q.all([SkillStatisticsModelFactory.apiPostProxy(“exportUserProgressData”, params)]
).then(function (response) {
var blob = new Blob([response[0].data], {type: “text/plain”});
$scope.saveAs(blob, ‘File_Name’ + ‘.csv’);
}, function (err) {
//console.log(err);
});
};

$scope.saveAs = function(blob, fileName)
{
if (window.navigator.msSaveOrOpenBlob) {
navigator.msSaveBlob(blob, fileName);
} else {
var link = document.createElement(‘a’);
link.href = window.URL.createObjectURL(blob);
link.download = fileName;
link.click();
window.URL.revokeObjectURL(link.href);
}
}

2. download excel file

server side

@userprogressreport.route(‘/mathjoy/api/v1.0/exportUserProgressData’, methods=[‘POST’])
def export_user_progress_data():

response = excel.make_response_from_array([[1, 2], [3, 4]], “xlsx”, file_name=”export_data”)

client side

$scope.exportUserProgressData = function () {
var params = $scope.getQueryParameter();

//$q.all([SkillStatisticsModelFactory.apiPostProxy(“exportUserProgressData”, params)]
//).then(function (response) {
// //var blob = new Blob([response[0].data], {type: “text/plain”});
// //$scope.saveAs(blob, ‘my_excel’ + ‘.csv’);
// var blob = new Blob([response[0].data], {type: ‘application/vnd.openxmlformats-officedocument.spreadsheetml.sheet’});
// $scope.saveAs(blob, ‘my_excel’ + ‘.xlsx’);
//}, function (err) {
// //console.log(err);
//});

$http({
url: ‘mathjoy/api/v1.0/exportUserProgressData’,
method: ‘POST’,
responseType: ‘arraybuffer’,
data: params,
headers: {
‘Content-type’: ‘application/json’,
‘Accept’: ‘application/vnd.openxmlformats-officedocument.spreadsheetml.sheet’
}
}).success(function(response){
var blob = new Blob([response], {type: ‘application/vnd.openxmlformats-officedocument.spreadsheetml.sheet’});
$scope.saveAs(blob, ‘my_excel’ + ‘.xlsx’);
}).error(function(){
//Some error log
});
};

 

 

Renaming a virtualenv folder without breaking it

http://stackoverflow.com/questions/6628476/renaming-a-virtualenv-folder-without-breaking-it

If you want to fix this manually, that is the way:

1. modify /tmp/project/env/bin/activate with yout favoriate editor like Vim, usually in Line 42

VIRTUAL_ENV=’/tmp/myproject/env’ => VIRTUAL_ENV=’/tmp/project/env’

2. modify /tmp/project/env/bin/pip in Line 1

#!/tmp/myproject/env/bin/python => #!/tmp/project/env/bin/python

Load data in a json file into mongo db

“””
Load data in a json file into mongo db
“””
import os
import json
from pymongo import MongoClient

CONN_STR = ‘mongodb://{}’
CONN_STR_AUTH = ‘mongodb://{}:{}@{}’

DB_NAME = “”
MONGO_SERVER = “127.0.0.1:27017”

conn_str = CONN_STR.format(MONGO_SERVER)
conn = MongoClient(conn_str)

db = conn[DB_NAME]

def get_collection_name_by_file(file_path):
“””
“””
collection_name = os.path.splitext(os.path.basename(file_path))[0]
return collection_name.replace(“-“, “_”)
def load_array_to_db(data, clear=False):
“””
“””
collection_name = get_collection_name_by_file(json_path)
collection = db[collection_name]
if clear:
# db.drop_collection(collection_name)
collection.remove({})

for item in data:
collection.insert(item)
def load_json_file_to_db(json_path, clear=False):
“””
“””
try:
with open(json_path) as data_file:
data = json.load(data_file)
load_array_to_db(data, clear)
except Exception as e:
print “load json file failed with error : {0}”.format(e.message)

print “Finished…”
if __name__ == ‘__main__’:
base_dir = os.path.dirname(os.path.realpath(__file__))
json_path = os.path.join(base_dir, “follower.json”)
load_json_file_to_db(json_path, clear=True)

Set row color in ui-grid conditionally

$scope.regularAssignmentGridOptions = {
rowTemplate: ‘

ng-style=” row.entity.target == 4 && {\’font-weight\’:\’bold\’,\’color\’:\’red\’}”>

‘,
columnDefs: [
{name: ‘grade’, width: ‘5%’},
{name: ‘type’, width: ‘8%’},
{name: ‘start’, width: ‘6%’, displayName: ‘Start Level/Score ‘},
{name: ‘target’, width: ‘6%’,displayName: ‘Target Level/Score ‘},
]
}

Python obj to JSON in Flask

Python object to/from JSON string

import json

user = {
    "name": "Test",
    "_id": "1234567890",
    "address": {
        "street": "De Anza",
        "city": "San Jose"
    }
}


json_from_user = json.JSONEncoder().encode(user)

print json_from_user

user_from_json = json.JSONDecoder().decode(json_from_user)

print user_from_json

Best article about H-bridge.

http://hardwarefun.com/tutorials/creating-robots-using-arduino-h-bridge

The following is the explanation for the different pins of the IC.

Vcc1 (pin 16) takes in regulated 5V for operating the IC.

Vcc2 (pin 8) takes the external voltage (up to 36V) which

1,2 EN (pin 1) and 3,4 EN (pin 9) are the enable pins for the two motors

1A (pin 2) and 2A (pin 7) are the control pins for Motor 1. These will be connected to Arduino.

1Y (pin 3) and 2Y (pin 6) are the output pins for Motor 1. These will be connected to the first motor.

3A (pin 10) and 4A (pin 15) are the control pins for Motor 2. These will be connected to Arduino.

3Y (pin 11) and 4Y (pin 14) are the output pins for Motor 2. These will be connected to the second motor.

pins 4,5,12,13 are Gnd pins

2000minuts 365days/$80 CDMA Cell phone

1. Buy a “Page Plus Cellular Prepaid Wireless Airtime Minutes Refill” at http://www.callingmart.com/
Select 2 Steps to Buy a Wireless Refill

Select “Page Plus Cellular Prepaid Wireless Airtime Minutes Refill” and $80
Before Checkout, try to find out(Google) Coupon Code. The coupon code can save your money.
After that, you will get a PIN number

2. Go to https://www.pagepluscellular.com/
Select Activate or to active your CDMA cellphone by providing the ESN or MEID of your cellphone and the PIN number you got from http://www.callingmart.com/
If you don’t know what is ESN or MEID, please go to https://www.pagepluscellular.com/activate/new-activation/

3. After step 2, you will go a serial number. You can active your phone by dialing this serial number with your phone.

Now, your phone works.