How would you shape an EF Core query for an API list that needs related names and summary counts?

Project an EF Core query into an API DTO with nested summary data

Explains EF Core projections for API read models that need related names, counts, and summaries without loading full graphs.

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I would start from the response DTO and select only the fields the API needs. For example, an order list might project order id, status, customer name, created time, and item count. EF Core can translate many projections and aggregates into SQL, so the database does the set-based work. I would avoid loading full entities and then mapping in memory when the endpoint only needs a summary.

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DTO projection, query shape, aggregation, nested data, row multiplication, and API read-model boundaries.

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API list and detail screens usually need purpose-built read shapes rather than complete tracked entity graphs. Projection can push related names, counts, totals, and selected fields into set-based SQL while keeping payloads bounded.
I would start from the response DTO and select only the fields the API needs. For example, an order list might project order id, status, customer name, created time, and item count. EF Core can translate many projections and aggregates into SQL, so the database does the set-based work. I would avoid loading full entities and then mapping in memory when the endpoint only needs a summary.
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I would pay attention to cardinality. Many-to-one values such as customer name usually project cleanly, while one-to-many collections can multiply rows or create heavy nested results. For counts or totals, I would use aggregate expressions in the projection. For nested collections, I might use a separate query keyed by parent ids or a purpose-built read model. The shape needs to keep SQL understandable and the payload bounded.

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Loading full entities for a list endpoint that needs a few fields.
Computing counts in memory after loading child rows.
Ignoring one-to-many row multiplication.
Adding response fields without checking generated SQL.

How would you shape an EF Core query for an API list that needs related names and summary counts?

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