OData v4 Params Parsing Library

This library provides a parser for OData v4 $filter expressions. It converts these expressions into an Abstract Syntax Tree (AST), allowing for further processing and evaluation. The parser supports a wide range of logical operators, comparison operators, function calls, and nested expressions, making it highly versatile for complex querying needs.

Note that this is a work in progress. A full list of specification components that are supported and not supported will be added in the next release.

Features

Logical Operators: and, or, not
Comparison Operators: eq, ne, gt, lt, ge, le
Function Calls: Ex: startswith, endswith, contains, concat
Grouping: Nested expressions with parentheses
Data Types: String, Number, Boolean, Date, Time, DateTime with Time Zone

Data Types

The library supports the following data types in expressions:

String: Enclosed in single quotes 'example'
Number: Integer and decimal numbers 123, 45.67
Boolean: true, false
Date: ISO 8601 format YYYY-MM-DD
DateTime: ISO 8601 format with time YYYY-MM-DDTHH:MM:SSZ
Time: ISO 8601 format HH:MM:SS

Testing

The library includes a set of tests mostly generated by AI to catch regressions.

You can run the tests using the following command:

cargo test

Installation

To add this library to your project, add the following to your Cargo.toml:

[dependencies]
odata-params = "0.1.0"

Example

Here is an example of how to parse a simple filter expression:

use odata_params::filters::parse_str;

fn main() {
    let filter = "name eq 'John' and isActive eq true";
    let result = parse_str(filter).expect("valid filter tree");

    println!("{:#?}", result);
}

Supported Expressions

Logical Operators

use odata_params::filters::parse_str;

let filter = "name eq 'John' or isActive eq true";
let result = parse_str(filter).expect("valid filter tree");

// Expression: (name = 'John') OR (isActive = true)

Comparison Operators

use odata_params::filters::parse_str;

let filter = "price lt 99.99";
let result = parse_str(filter).expect("valid filter tree");

// Expression: price < 99.99

Function Calls

use odata_params::filters::parse_str;

let filter = "endswith(name, 'Smith')";
let result = parse_str(filter).expect("valid filter tree");

// Expression: endswith(name, 'Smith')

Advanced Usage

Nested Grouping

use odata_params::filters::parse_str;

let filter = "((name eq 'John' and isActive eq true) or (age gt 30 and age lt 50))";
let result = parse_str(filter).expect("valid filter tree");

// Expression: ((name = 'John') AND (isActive = true)) OR ((age > 30) AND (age < 50))

Functions with Comparisons

use odata_params::filters::parse_str;

let filter = "concat(concat(city, ', '), country) eq 'Berlin, Germany'";
let result = parse_str(filter).expect("valid filter tree");

// Expression: concat(concat(city, ', '), country) = 'Berlin, Germany'

odata-params 0.1.1