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https://github.com/danielhasan1/fastapi-listing

Advanced items listing library that gives you freedom to design complex listing REST APIs that can be read by human.
https://github.com/danielhasan1/fastapi-listing

fastapi json library listing-api python rest-api web

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Advanced items listing library that gives you freedom to design complex listing REST APIs that can be read by human.

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README

        

# fastapi-listing

Advanced items listing library that gives you freedom to design really complex listing APIs using component based architecture.

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Comes with:
- pre defined filters
- pre defined paginator
- pre defined sorter

## Advantage
- simplify the intricate process of designing and developing complex listing APIs
- Design components(USP) and plug them from anywhere
- Components can be **reusable**
- Best for fast changing needs

## Installing

Using [pip](https://pip.pypa.io/):

```python
pip install fastapi-listing
```

## Quick Example

Attaching example of it running against the [mysql employee db](https://dev.mysql.com/doc/employee/en/)

There are two ways to implement a listing API using fastapi listing

- inline implementation
- class based implementation

for both we will be needing a dao(data access object) class

### First let's look at inline implementation.

```python
# main.py

from fastapi import FastAPI
from pydantic import BaseModel, Field
from datetime import date

from sqlalchemy import Column, Date, Enum, Integer, String
from sqlalchemy.orm import declarative_base
from sqlalchemy.orm import Session

from fastapi_listing.paginator import ListingPage
from fastapi_listing import FastapiListing, MetaInfo
from fastapi_listing.dao import GenericDao

Base = declarative_base()
app = FastAPI()

class Employee(Base):
__tablename__ = 'employees'

emp_no = Column(Integer, primary_key=True)
birth_date = Column(Date, nullable=False)
first_name = Column(String(14), nullable=False)
last_name = Column(String(16), nullable=False)
gender = Column(Enum('M', 'F'), nullable=False)
hire_date = Column(Date, nullable=False)

# Dao class
class EmployeeDao(GenericDao):
"""write your data layer access logic here. keep it raw!"""
name = "employee"
model = Employee # sqlalchemy model class (support for pymongo/tortoise orm is in progress)

class EmployeeListDetails(BaseModel):
emp_no: int = Field(alias="empid", title="Employee ID")
birth_date: date = Field(alias="bdt", title="Birth Date")
first_name: str = Field(alias="fnm", title="First Name")
last_name: str = Field(alias="lnm", title="Last Name")
gender: str = Field(alias="gdr", title="Gender")
hire_date: date = Field(alias="hdt", title="Hiring Date")

class Config:
orm_mode = True
allow_population_by_field_name = True

@app.get("/employees", response_model=ListingPage[EmployeeListDetails])
def get_employees(db: Session):
dao = EmployeeDao(read_db=db)
# passing pydantic serializer is optional, automatically generates a
# select query based on pydantic class fields for easy cases like columns of same table
# if not passed then provide a select query in dao layer
return FastapiListing(dao=dao, pydantic_serializer=EmployeeListDetails
).get_response(MetaInfo(default_srt_on="emp_no")) # by default sort in desc order
# let's say pydantic class contains compute fields then pass custom_fields=True (by default False)
return FastapiListing(dao=dao,
pydantic_serializer=EmployeeListDetails,
custom_fields=True # here setting custom field True to avoid unknown attributes error
).get_response(MetaInfo(default_srt_on="emp_no"))
```

Voila 🎉 your very first listing response

![](https://drive.google.com/uc?export=view&id=1amgrAdGP7WvXfiNlCYJZPC9fz4_1CidE)

Auto generated query doesn't fulfil your use case❓️

```python
# Overwriting default read method in dao class
class EmployeeDao(GenericDao):
"""write your data layer access logic here. keep it raw!"""
name = "employee"
model = Employee

def get_default_read(self, fields_to_read: Optional[list]):
"""
Extend and return your query from here.
Use it when use cases are comparatively easier than complex.
Alternatively fastapi-listing provides a robust way to write performance packed queries
for complex APIs which we will look at later.
"""
query = self._read_db.query(Employee)
return query

@app.get("/employees", response_model=ListingPage[EmployeeListDetails])
def get_employees(db: Session):
dao = EmployeeDao(read_db=db)
# note we removed all optional named params here
return FastapiListing(dao=dao).get_response(MetaInfo(default_srt_on="emp_no"))
```

# Adding client site features

Django admin users gonna love filter feature. But before that lets do a little setup which no once can avoid to support a broad spectrum of clients unless you use native query param format which I doubt.

## Add your custom adaptor class for reading filter/sorter/paginator client request params

Below is the default implementation. You will be writing your own adaptor definition

```python
from typing import Literal
from fastapi_listing.service.adapters import CoreListingParamsAdapter
from fastapi_listing import utils

class YourAdapterClass(CoreListingParamsAdapter): # Extend to add your behaviour
"""Utilise this adapter class to make your remote client site:
- filter,
- sorter,
- paginator.
query params adapt to fastapi listing library.
With this you can utilise same listing api to multiple remote client
even if it's a front end server or other backend server.

fastapi listing is always going to request one of the following fundamental key if you want to use it
- sort
- filter
- pagination

supported formats for
filter:
simple filter - [{"field":"", "value":{"search":""}}, ...]
if you are using a range filter -
[{"field":"", "value":{"start":"", "end": ""}}, ...]
if you are using a list filter i.e. search on given items
[{"field":"", "value":{"list":[""]}}, ...]

sort:
[{"field":<"key used in sort mapper>", "type":"asc or "dsc"}, ...]
by default single sort allowed you can change it by extending sort interceptor

pagination:
{"pageSize": , "page": }
"""

def get(self, key: Literal["sort", "filter", "pagination"]):
"""
@param key: Literal["sort", "filter", "pagination"]
@return: List[Optional[dict]] for filter/sort and dict for paginator
"""
return utils.dictify_query_params(self.dependency.get(key))

```
### Once your adaptor class is set

## Adding filter feature

➡️ lets add filters on Employee for:
1. gender - return only **Employees** belonging to 'X' gender where X could be anything.
2. DOB - return **Employees** belonging to a specific range of DOB.
3. First Name - return **Employees** only starting with specific first names.
```python
from fastapi import Request
from sqlalchemy.orm import Session

from fastapi_listing.paginator import ListingPage
from fastapi_listing.filters import generic_filters # collection of inbuilt filters
from fastapi_listing.factory import filter_factory # register filter against a listing
from fastapi_listing import MetaInfo, FastapiListing

emp_filter_mapper = {
"gdr": ("Employee.gender", generic_filters.EqualityFilter),
"bdt": ("Employee.birth_date", generic_filters.MySqlNativeDateFormateRangeFilter),
"fnm": ("Employee.first_name", generic_filters.StringStartsWithFilter),
}
filter_factory.register_filter_mapper(emp_filter_mapper)

@app.get("/employees", response_model=ListingPage[EmployeeListDetails])
def get_employees(request: Request, db: Session):
dao = EmployeeDao(read_db=db)
return FastapiListing(request=request, dao=dao).get_response(
MetaInfo(default_srt_on="emp_no",
filter_mapper=emp_filter_mapper,
feature_params_adapter=YourAdapterClass))

# or you dont wanna pass request?
# extract required data from reqeust and pass it directly
params = request.query_params
filter_, sort_, pagination = params.get("filter"), params.get("sort"), params.get("paginator")

dao = EmployeeDao(read_db=db)
return FastapiListing(dao=dao).get_response(
MetaInfo(default_srt_on="emp_no",
filter_mapper=emp_filter_mapper,
feature_params_adapter=YourAdapterClass,
filter=filter_,
sort=sort_,
paginator=pagination))

```

### Let's break it down

**Filter mapper** - a collection of allowed filters on your listing API. Any request outside of this mapper scope
will not be executed for filtering safeguarding you from creepy API users.

`generic_filters` a collection of inbuilt filters supported by sqlalchemy orm
A dictionary is defined with structure:

`{"alias": tuple("sqlalchemy_model.field", filter_implementation)}`

`alias` - A string used by client in case if you wanna avoid actual column names to client site.

`tuple` - will contain two items field name and filter implementation

```python
from fastapi_listing.filters import generic_filters

emp_filter_mapper = {
"gdr": ("Employee.gender", generic_filters.EqualityFilter),
"bdt": ("Employee.birth_date", generic_filters.MySqlNativeDateFormateRangeFilter),
"fnm": ("Employee.first_name", generic_filters.StringStartsWithFilter),
}
```

Register the above mapper with filter factory.

```python
from fastapi_listing.factory import filter_factory

filter_factory.register_filter_mapper(emp_filter_mapper) # Register in global space or module level.
```

A client could request you like `v1/employees?filter=[{"gdr":"M"}]`

parse the above query_param in your adapter class like `[{"field":"gdr", "value":{"search":"M"}}]` if passed externally as kwarg then access it via `self.extra_context` in your adapter class or if passed request then
access `self.request` directly there.

Assuming everything goes right above will produce a response with items filtered on gender field matching rows with 'M'

**Sort Mapper** - a collection of allowed sort on listing any request outside of this mapper scope will
not be permitted for sort.

Simply define a dictionary with structure `{"alias": "field"}` if sorting on same column them omit model name &
if sorting on a joined table column then add sqlalchemy class name like we did for filter `{"alias":"sqlalchemy_model.field"}`

```python
listing_sort_mapper = {
"code": "emp_no"
}
return FastapiListing(dao=dao).get_response(
MetaInfo(default_srt_on="emp_no",
filter_mapper=emp_filter_mapper,
sort_mapper=listing_sort_mapper,
feature_params_adapter=YourAdapterClass,
filter=filter_,
sort=sort_,
paginator=pagination))

# OR if passing request obj
return FastapiListing(request=request, dao=dao).get_response(
MetaInfo(default_srt_on="emp_no",
filter_mapper=emp_filter_mapper,
sort_mapper=listing_sort_mapper,
feature_params_adapter=YourAdapterClass))
```

A client could request you like `v1/employees?sort={"code":}` or followed by filter `v1/employees?filter=[{"gdr":"M"}]&sort={"code":, "type":"asc"}`
and the response should contain list items sorted by employee code column in ascending order.

**Note** we didn't registered sort mapper like we did for filter mapper.

Similarly, for paginator `v1/employees?pagination={"page":1, "pageSize":10}` or followed by filter and sort `v1/employees?filter=[{"gdr":"M"}]&sort={"code":, "type":"asc"}&pagination={"page":1, "pageSize":10}`

Above will produce listing page of items 10 or dynamically client could change page size.

One thing to **Note** here is fastapi listing by default limits the client to reuqest maximum of 50 items at a time to safeguard your database
if you want to increase/decrease this default limit then simply pass the limit in `MetaInfo`

**You can also change the default page size from 10 to anything you would want**

```python
return FastapiListing(request=request, dao=dao).get_response(
MetaInfo(default_srt_on="emp_no",
filter_mapper=emp_filter_mapper,
sort_mapper=listing_sort_mapper,
max_page_size=25, # here change max page size
default_page_size=10, # here change default page size
feature_params_adapter=YourAdapterClass))
```

### Class Based implementation
Quick Example to convey the context

```python
from fastapi import FastAPI

from sqlalchemy import Column, Date, String, ForeignKey
from sqlalchemy.orm import declarative_base
from sqlalchemy.orm import Session, relationship
from fastapi_listing import ListingService, FastapiListing
from fastapi_listing.filters import generic_filters
from fastapi_listing import loader
from fastapi_listing.paginator import ListingPage

Base = declarative_base()
app = FastAPI()

class Title(Base):
__tablename__ = 'titles'

emp_no = Column(ForeignKey('employees.emp_no', ondelete='CASCADE'), primary_key=True, nullable=False)
title = Column(String(50), primary_key=True, nullable=False)
from_date = Column(Date, primary_key=True, nullable=False)
to_date = Column(Date)

employee = relationship('Employee')


class EmployeeDao(GenericDao):
name = "employee"
model = Employee

class TitleDao(GenericDao):
name = "title"
model = Title

@loader.register()
class EmployeeListingService(ListingService):
"""Class based listing API implementation"""
filter_mapper = {
"gdr": ("Employee.gender", generic_filters.EqualityFilter),
"bdt": ("Employee.birth_date", generic_filters.MySqlNativeDateFormateRangeFilter),
"fnm": ("Employee.first_name", generic_filters.StringStartsWithFilter),
"lnm": ("Employee.last_name", generic_filters.StringEndsWithFilter),
# below feature will require customisation to work at query level
"desg": ("Employee.Title.title", generic_filters.StringLikeFilter, lambda x: getattr(Title, x)) # registering filter with joined table field
}

sort_mapper = {
"cd": "emp_no"
}
default_srt_on = "Employee.emp_no"
default_dao = EmployeeDao

def get_listing(self):
# similar to above inline but instead of passing meta info uncompressed we pass self
# rest is handled implicityly like filter register
# one advantage here is every expect is validated so you get error when running server
resp = FastapiListing(self.request, self.dao, pydantic_serializer=EmployeeListDetails).get_response(self.MetaInfo(self))
return resp


@app.get("/employees", response_model=ListingPage[EmployeeListDetails])
def get_employees(db: Session):
return EmployeeListingService(read_db=db).get_listing()
```

Check out [docs](https://fastapi-listing.readthedocs.io/en/latest/tutorials.html#adding-filters-to-your-listing-api) for supported list of filters.
Additionally, you can create **custom filters** as well.

## Provided features are not meeting your requirements???

The Applications are endless with customisations

➡️ You can write custom:

* Query
* Filter
* Sorter
* Paginator

You can check out customisation section in docs after going through basics and tutorials.

Check out my other [repo](https://github.com/danielhasan1/test-fastapi-listing/blob/master/app/router/router.py) to see some examples

## Features and Readability hand in hand 🤝

- Well defined interface for filter, sorter, paginator
- Support Dependency Injection for easy testing
- Room to adapt the existing remote client query param semantics
- Write standardise listing APIs that will be understood by generations of upcoming developers
- Write listing features which is easy on human mind to extend or understand
- Break down the most complex listing data APIs into digestible piece of code

Why readability and code quality matters in one picture...

# Documentation
View full documentation at: https://fastapi-listing.readthedocs.io (A work in progress)

# Feedback, Questions?

Any form of feedback and questions are welcome! Please create an issue 💭
[here](https://github.com/danielhasan1/fastapi-listing/issues/new).