cherry-stock

This project basically implements a cherrypy webserver to search and list stock data. It downloads the data from a given url, parses it stores it in a redis database. When user search a stock it looks into the database fetches it and returns the redered html as a table structure.

Project directory structure

|-- LICENSE
|-- README.md
|-- requirements.txt
|-- main.py
`-- public
    |-- css
    |   `-- style.css
    `-- index.html

Explanation of each functions and class in main.py

• get_download_url(url): It takes the original given url as argument fetch the webpage extracts all the links in the page then filters the link referred to bhav copy zip file. It returns the download link.

• download_zip_file(download_url): It takes the download_url as argument downloads and saves it in working directory and returns ZIP file name.

• extract_zip(zip_file_name): Takes the zip_file_name as argument and extracts the CSV file in it and returns the CSV file name.

• prepare_csv_data(csv_file_name): Takes the csv_file_name as argument reads the csv file prepares the data and returns a list of dictionary which holds the data. The return type is [{key1:'val11',..},{key1:'val12',..},...{key1:'val1n',..}].

• strip_name(data_dict): Basically the SC_NAME field contains the name of each Stock which has more than one empty spaces at last. This function takes an individual data_dict as argument then gets the value of the key 'SC_NAME' then strips the empty space and returns the dictionary.

• modify_name_field(bhav_copy_dict): Here it takes the entire list of data dictionary updates the 'SC_NAME' field by the help of strip_name() function and returns it.

• stock_names(bhav_copy_dict): Creates a list of all stock names from the bhav_copy_dict passed, ehich will be used for setting hash keys and searching purposes.

• prepare_database(pipeline, bhav_copy_dict): It takes an pipeline object and the list of dictionary as input sets the data in redis database server.

• prepare_template(template_dir): This function takes the template_dir as arguments where all the static files are stored and creates a template object of index.html and returns it.

• auto_complete_list(search_str, names): Takes the search_str and list of stock names as input, search for starting pattern in each item of the list. If any match or matches found returns the append it to a list and returns it.

• get_from_db(key): Here type(url) = str. Takes the hash key as the arguments fetches the data from database and returns it. It also uses a connection object which is globally availavle.

• DisplayStocks(): This is the main class. A instance of this will be provided as a argument in cherrypy.quickstart() function. It has two main methods explained below.

  • index(count=10): This method controls the logic how the home page will be displayed.The count argument passed to show the number of stocks data to be rendered. It is controlled by serverside logic. Need to implement client side logic to control the number of stocks to be displayed.
  • search_stock(name=''): It takes a 'string' as an user argument from client side and search through the stock_names list, if found any matches retrieves the data from database renders the html and returns it to client.

Explanation of arguments used in template.render()

Basically it renders the index.html document in public/ folder. The template.render() function takes 3 arguments to render a dynamic html document. First argument is a fields list, the second is count and the third is the list of data in dictionary format named stock_data.

<tr>
 {% for field in fields %}
    <th>{{field}}</th>
        {% endfor %}
</tr>

Here in the above first we render the table header with required fields. For this reason we use a for-loop block. For this we need fields as first argument passed in the template.render() function.

{% for data in stock_data[:count] %}
    <tr>
        {% for field in fields %}
            <td>{{data[field]}}</td>
        {% endfor %}
    </tr>
 {% endfor %}

In the above case we need three arguments. First is the stock_data and the count number. The stock_data is a list of dictionary object which holds the data. The fields argument is the same as above. The first for loop iterates through the each item in stock_data[:count] and then the second for loop iterates through the each field in fields and renders the html table.

Explanation of template.render()

template.render(fields=FIELDS, count=cnt, stock_data=list(map(lambda x: get_from_db(x), search_list[:cnt])))

This function takes three arguments already mentioned above.

get_from_db(x) function takes the hash key value as the argument retrieve data from database. Here in this function we also use a global client named conn.

search_list is the list object contains the value of SC_NAME fields. The map() function maps each item of search_list to get_from_db() function and returns a python generator object. Then use the list() function to iterate through each mapping and retrieves the data.