Flattened Projections

By default, FlexQuery.NET preserves the original object hierarchy. However, for reporting or integration with legacy systems, you might need to flatten nested collections into a linear rowset.

Flat Mode (mode=flat)

Linearizes a single navigation path into a flat list of leaf objects.

Query:?select=orders.orderItems.productName as product,orders.orderItems.quantity as qty&mode=flat

Output:

[
  { "product": "Laptop", "qty": 1 },
  { "product": "Mouse", "qty": 2 }
]

Generated LINQ: The library builds a sequential SelectMany chain:

query.SelectMany(c => c.Orders)
     .SelectMany(o => o.OrderItems)
     .Select(oi => new { product = oi.ProductName, qty = oi.Quantity })

NOTE

Constraint: mode=flat requires a single linear navigation path. Branching into multiple collections will trigger a validation error.

Flat-Mixed Mode (mode=flat-mixed)

Flattens root entity fields alongside deeply nested collection fields into a single rowset, preserving parent context.

Query:?select=id as customerId,name,orders.status as orderStatus,orders.orderItems.productName as product&mode=flat-mixed

Output:

[
  { "customerId": 1, "name": "Alice", "orderStatus": "Shipped", "product": "Laptop" },
  { "customerId": 1, "name": "Alice", "orderStatus": "Shipped", "product": "Mouse" }
]

Generated LINQ: The library carries context through the chain using correlated SelectMany projections:

query.SelectMany(c => c.Orders, (c, o) => new { c, o })
     .SelectMany(x => x.o.OrderItems, (x, oi) => new {
         customerId = x.c.Id,
         name = x.c.Name,
         orderStatus = x.o.Status,
         product = oi.ProductName
     })

This mode allows you to "join" all levels of a hierarchy into a flat result set while maintaining full EF Core server-side translation.