Struct FragmentResolver 

pub struct FragmentResolver { /* private fields */ }

Resolves GraphQL fragment spreads in query selection sets.

Handles fragment spreads (...FragmentName) by expanding them to their actual field selections. Also merges multiple fragment definitions and handles field deduplication.

Example

use fraiseql_core::graphql::{FragmentResolver, FragmentDefinition, FieldSelection};

let fragment = FragmentDefinition {
    name: "UserFields".to_string(),
    type_condition: "User".to_string(),
    selections: vec![
        FieldSelection {
            name: "id".to_string(),
            alias: None,
            arguments: vec![],
            nested_fields: vec![],
            directives: vec![],
        },
    ],
    fragment_spreads: vec![],
};

let resolver = FragmentResolver::new(&[fragment]);

Implementations

impl FragmentResolver

pub fn new(fragments: &[FragmentDefinition]) -> Self

Create a new fragment resolver from a list of fragment definitions.

pub fn with_max_depth(self, max_depth: u32) -> Self

Create a resolver with a custom max depth.

pub fn resolve_spreads( &self, selections: &[FieldSelection], ) -> Result<Vec<FieldSelection>, FragmentError>

Resolve all fragment spreads in selections.

Errors

Returns error if:

• Fragment is not found
• Fragment depth exceeds maximum
• Circular references are detected

pub fn evaluate_inline_fragment( selections: &[FieldSelection], type_condition: Option<&str>, actual_type: &str, ) -> Vec<FieldSelection>

Handle inline fragments with type conditions.

Evaluates whether an inline fragment applies based on type conditions. Returns the selections if the type condition matches, or an empty vector if it doesn’t.

pub fn merge_selections( base: &[FieldSelection], additional: Vec<FieldSelection>, ) -> Vec<FieldSelection>

Merge field selections from multiple sources (e.g., fragment spreads).

Handles:

• Combining fields from multiple fragments
• Deduplicating fields by name/alias
• Merging nested selections