What is OData?¶

OData in One Sentence¶

OData (Open Data Protocol) is a standard way to query data via URLs.

Instead of inventing your own query parameters, you use OData syntax that millions of developers already know.

Why Not Invent Your Own?¶

The Problem: Every API is Different¶

# Fictitious API A
GET /posts?fields=id,title&author_id=5&sort=-date&limit=10

# Fictitious API B
GET /posts?include=id,title&filter[author]=5&order=date:desc&per_page=10

# Fictitious API C
GET /posts?columns=id,title&where=author_id:5&orderby=date&dir=desc&take=10

Problems: - Developers must learn a new syntax for each API - Documentation burden for every project - No tooling support - Inconsistent error handling

The Solution: OData Standard¶

# OData - same everywhere
GET /posts?$select=id,title&$filter=author/id eq 5&$orderby=date desc&$top=10

Benefits: - Same syntax in Microsoft, SAP, Salesforce APIs - Extensive documentation online - Client libraries in every language - Consistent, predictable behavior

OData Query Parameters¶

Parameter	Purpose	Example
`$select`	Choose fields	`$select=id,title,status`
`$filter`	Filter results	`$filter=status eq 'published'`
`$expand`	Include relations	`$expand=author,categories`
`$orderby`	Sort results	`$orderby=created_at desc`
`$top`	Limit count	`$top=10`
`$skip`	Skip (offset)	`$skip=20`
`$count`	Include total	`$count=true`

$filter Syntax¶

Comparison Operators¶

$filter=price eq 100      # Equal
$filter=price ne 100      # Not equal
$filter=price gt 100      # Greater than
$filter=price ge 100      # Greater or equal
$filter=price lt 100      # Less than
$filter=price le 100      # Less or equal

Logical Operators¶

$filter=price gt 100 and status eq 'active'
$filter=status eq 'draft' or status eq 'review'
$filter=not (status eq 'deleted')

String Functions¶

$filter=contains(title, 'Django')
$filter=startswith(name, 'John')
$filter=endswith(email, '@example.com')

Nested Properties¶

$filter=author/name eq 'John'
$filter=author/company/country eq 'Spain'

Collections (any/all)¶

$filter=categories/any(c: c/name eq 'Tech')
$filter=tags/all(t: t/active eq true)

Real Examples¶

Simple List¶

GET /posts?$top=10&$orderby=created_at desc

Filtered with Field Selection¶

GET /posts?$filter=status eq 'published'&$select=id,title,excerpt

GET /posts?$expand=author($select=name,email)&$filter=featured eq true

Paginated with Count¶

GET /posts?$top=10&$skip=20&$count=true

Complex Query¶

GET /posts?$filter=status eq 'published' and rating gt 4.0&$select=id,title,rating&$expand=author&$orderby=rating desc&$top=5

Why FC Selector Uses OData¶

No need to invent - Standard already exists
Documentation exists - Microsoft, SAP docs apply
Powerful - Handles complex queries elegantly
Familiar - Many developers know it
Tooling - Client libraries, Swagger support

OData is Just the Query Language¶

FC Selector uses OData as the query syntax, not as a full OData server.

# OData query string
"$filter=status eq 'published'&$select=id,title"

# Parsed and converted to Django ORM
Post.objects.filter(status='published').only('id', 'title')

You get the expressive power of OData with the performance of Django ORM.