Struct AggregationProjector 

pub struct AggregationProjector;

Aggregation result projector

Implementations

impl AggregationProjector

pub fn project( rows: Vec<HashMap<String, Value>>, _plan: &AggregationPlan, ) -> Result<Value>

Project SQL aggregate results to GraphQL JSON.

Arguments

• rows - SQL result rows as HashMaps
• plan - Aggregation execution plan (for metadata)

Returns

GraphQL-compatible JSON response

Errors

Currently infallible; reserved for future extension (e.g., type coercion failures).

Example

// Requires: an AggregationPlan built from compiled schema metadata.
// See: tests/integration/ for runnable examples.
use std::collections::HashMap;
use serde_json::{json, Value};

let mut row = HashMap::new();
row.insert("category".to_string(), json!("Electronics"));
row.insert("count".to_string(), json!(42));
row.insert("revenue_sum".to_string(), json!(5280.50));
let rows = vec![row];
// let result = AggregationProjector::project(rows, &plan)?;
// result: [{"category": "Electronics", "count": 42, "revenue_sum": 5280.50}]

Errors

Returns FraiseQLError::Internal if JSON serialization of the projected rows fails (should not occur for well-formed input).

pub fn wrap_in_data_envelope(projected: Value, query_name: &str) -> Value

Wrap projected results in GraphQL data envelope.

Arguments

• projected - Projected result array
• query_name - GraphQL query field name (e.g., “sales_aggregate”)

Returns

Complete GraphQL response with {"data": {...}} wrapper

Example

let projected = json!([{"count": 42}]);
let response = AggregationProjector::wrap_in_data_envelope(projected, "sales_aggregate");
// response: {"data": {"sales_aggregate": [{"count": 42}]}}
assert!(response.get("data").is_some());

pub fn project_single( row: HashMap<String, Value>, _plan: &AggregationPlan, ) -> Result<Value>

Project a single aggregate result (no GROUP BY).

When there’s no GROUP BY, the result is a single object, not an array.

Errors

Currently infallible; reserved for future extension (e.g., type coercion failures).

Example

// Requires: an AggregationPlan built from compiled schema metadata.
// See: tests/integration/ for runnable examples.
use std::collections::HashMap;
use serde_json::json;

let mut row = HashMap::new();
row.insert("count".to_string(), json!(100));
row.insert("revenue_sum".to_string(), json!(5000.0));
// let result = AggregationProjector::project_single(row, &plan)?;
// result: {"count": 100, "revenue_sum": 5000.0}