Field Types and RunTime Field in Web2Py

Field Types and RunTime Field in Web2Py

Firstly we will learn the Field types, and later we will move to the Runtime Field.

💥As defined in the Python decimal module, decimal demands and returns values as Decimal objects. We internally treat the decimal type as a double because SQLite cannot handle it. The (n,m) variables denote the total number of digits and the number of digits following the decimal point.

💥Only a few database engines support the big-id and big-reference, and they are both experimental. The DAL constructor provides a bigint_id option that, when set to True, converts the id fields and reference fields into big-id and big-reference, respectively, even though they aren't often utilized as field types outside of legacy tables. Moving ahead in Field Types and Runtime field.

💥The list: fields are unique because they are created to take advantage of certain denormalization features on NoSQL (in the case of a Google App Engine NoSQL, the field types ListProperty and StringListProperty) and back-port them to all other supported relational databases. Lists are stored in relational databases as text fields. Each | in the string item is escaped as a ||. The items are separated by a |. They are covered in the chapter's list: and contains section.

💥JSON field types are generally self-explanatory. Any JSON serializable object can be stored in it. It is portably built to work with the various database adapters while optimizing for MongoDB. And our last point for Field types in Field types and Runtime Field discussion is,

💥Blob fields are additionally unique. By default, base64 encoding is used to encode binary data before it is put into the database field and decode it when extracted. The communication is independent of backend-specific escape rules, but this has the drawback of utilizing 33 percent more storage space in blob fields than is necessary.

For  Field Types and RunTime Field in Web2Py, the above points need to be clarified

The various Field Types used in Web2Py are listed below.

RunTime Field in Web2Py 

Now, continuing to the next section of Field Types and Runtime Field in Web2Py

The majority of field and table properties can be changed once they are defined:

>>> dBase.define_table('person', Field('name', default=''), format='%(name)s')
<Table person (id, name)>
>>> db.person._format = '%(name)s/%(id)s'
>>> db.person.name.default = 'codingninjas'

To avoid conflicts that may arise with field names, table attributes are typically prefixed with an underscore in Field Type and Runtime Field.

For a certain database connection, you can list the specified tables:

>>> dBase.tables
['person']

For the type, you can perform the query:

>>> type(dBase.person)
<class 'pydal.objects.Table'>

Given a field name, you can easily access the attributes set in its definition by using:

>>> dBase.person.name.type
string
>>> dBase.person.name.unique
False
>>> dBase.person.name.notnull
False
>>> dBase.person.name.length
12

Including the parent table, tablename, and parent connection by the following methods-

>>> dBase.person.name._table == db.person
True
>>> dBase.person.name._tablename == 'person'
True
>>> dBase.person.name._db == db
True

Methods can be found in a field. We will discuss some of them later because they are used to construct queries. The field object's special method, validate, calls the field's validators in Field types and the Runtime field.

>>> dbase.person.name.validate('John')
('John', None)

which returns a tuple (value, error), and the error is None if the input passes validation.

Now, as we have covered various field types and RunTime Field, Let's move to the FAQs section to discuss some FAQs over Field types and RunTIme Field.

Frequently Asked Questions

What is Web2Py?

Web developers can program dynamic web content using Python, which is possible due to Web2py. Although a web developer can still create a form from scratch if necessary, Web2py is intended to help decrease repetitive web development processes, such as creating web forms from scratch.

What is SQLite used for?

Desktop applications like version control systems, financial analysis tools, media categorization and editing suites, CAD packages, record-keeping programs, and others frequently use SQLite as the on-disk file format.

What is pyDAL?

An entirely Python database abstraction layer is called pyDAL. The pyDAL module dynamically creates the SQL for the database back end in the chosen language.

What is the difference between SQL and SQLite?

The standard SQL language describes establishing relational structure, entering or updating data in relationships, initiating and terminating transactions, etc. SQLite is File-based. It differs from other SQL databases in that it lacks a distinct server process, unlike most other SQL databases.

MySQL vs SQLite: Which is superior?

MySQL is a superior option if you need scalability regarding the number of database queries needed. MySQL defeats SQLite if you need genuine parallelism, stricter security standards, or the ability to govern user permissions.

Conclusion

In this article, we have extensively discussed Field Types and RunTime Field in Web2Py.

To learn more about Web2Py, see Troubleshooting Web2Py, What is Web2Py, Introduction to Web2Py, Creating a New Application, Prepare the tool. 

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