flask-sqlalchemy-qs is a Python library that enables processing of query strings and its usage in conjunction with Flask and SQLAlchemy. The library provides tools for generating and manipulating SQLAlchemy filters and sorts from query strings in the URL, making it easier to build robust and flexible RESTful APIs.
A User model has a username column attribute to filter:
/users?filters[username][eq][email protected]
A User model has a person relationship attribute, and a list of users has to be filtered and sorted by an attribute of that relationship:
/users?filters[person][age][gte]=22&sorts[0][person][age]=DESC&limit=10&offset=0
Install flask-sqlalchemy-qs with pip:
pip install flask-sqlalchemy-qsTo get the filters, sorts, limit, and offset from the query string is necesarry to follow the next syntaxis:
Filter your list result by column and relationship model properties.
GET /api/endpoint?filters[field][operator]=value
The following operators are available:
| Operator | Description |
|---|---|
| eq | Equal |
| ne | Not equal |
| is | Is |
| is_not | Is not |
| lt | Less than |
| lte | Less than or equal to |
| gt | Greater than |
| gte | Greater than or equal to |
| in | Included in an array |
| nin | Not included in an array |
| contains | Contains |
| ncontains | Does not contain |
| icontains | Contains (case-insensitive) |
| like | Like |
| ilike | Like (case-insensitive) |
| not_like | Not Like |
| not_ilike | Not Like (case-insensitive) |
| nicontains | Does not contain (case-insensitive) |
| startswith | Starts with |
| istartswith | Starts with (case-insensitive) |
| endswith | Ends with |
| iendswith | Ends with (case-insensitive) |
| or | Joins the filters in an "or" expression |
| and | Joins the filters in an "and" expression |
| not | Joins the filters in an "not" expression |
- Simple usage
/users?filters[username][eq][email protected]
- Relationship usage (User has a person)
/users?filters[person][name][eq]=Marco
- Multiple usage
/users?filters[username][contains]=awesome.com&filters[person][age][gte]=25
- In and nin usage
/users?filters[person][age][in][0]=20&filters[person][age][in][1]=25&filters[person][age][in][2]=30
- Boolean usage
/users?filters[or][0][username][eq]=username1&filters[or][1][username][eq]=username2
- Complex boolean usage
/users?filters[or][0][username][contains]=awesome.com&filters[or][1][not][0][and][0][person][age][gte]=20&filters[or][1][not][0][and][1][person][age][lte]=30
- JSON support followed by dot notation
/users?filters[json_column.foo][eq]=bar
Sort your list result by column and relationship model properties.
GET /api/endpoint?sorts[priority_index][field]=order
- Single sort usage
/users?sorts[0][username]=DESC
- Multiple order priority and relationship usage
/users?sorts[0][username]=DESC&sorts[1][person][age]=ASC
Limt (amount of elements) and offset (amount of skipped elements) for your list result.
GET /api/endpoint?limit=10&offset=2
/users?limit=100&offset=5
In order to use it in the sqlalchemy query object. The BaseQuery needs to be imported and set as the query_class in the model
from typing import Dict, List, Tuple, Union
from flask_sqlalchemy_qs import get_url_query_ctx, BaseQuery
...
db = SQLAlchemy(app)
# In this case, a Base Model is defined with its query_class attribute set to BaseQuery
class Base(db.Model):
__abstract__ = True
query_class = BaseQuery
class User(Base):
id = db.Column(db.Integer, primary_key=True)
...
...
#Types
FilterType = Dict[str, Union[bool, str, Dict]]
SortType = Dict[str, Union[str, Dict]]
...
@myblueprint.route('/users', methods=['GET'])
def get_all_users():
#Get the query string in the correct format
ctx: Dict[str, Union[FilterType, List[SortType], int]] = get_url_query_ctx()
filters:FilterType = ctx["filters"]
sorts:List[SortType] = ctx["sorts"]
limit:int = ctx["limit"]
offset:int = ctx["offset"]
#Query the model with the extended methods
query = User.query.filter_by_ctx(filters=filters) \
.sort_by_ctx(sorts=sorts) \
.offset(offset) \
.limit(limit)
...
results = query.all()
...1.1.4
SQLALCHEMYSQLAlchemy~=2.0
flask~=2.2
flask-sqlalchemy~=3.0
Contributions to this project are welcome. Please open an issue or make a pull request.
This project is licensed under the terms of the MIT license.
If you have any issues or suggestions, please open an issue on this repository.
Marco Gil, [email protected]