FromRow
FromRow is a type-class or trait abstraction for converting a database query result row into a typed program value.
Rust Servers, Services, and Apps
FromRow is an SQLx trait for constructing a Rust value from a database query result row.
- How it is used
- Maps course query results into `Course` values in a Rust web API’s database-access layer.
- How deep it goes
- Shows a derive and its use with `query_as!`, while leaving trait internals and a handwritten `FromRow` implementation unexplored.
- Examples
- Uses a `Course` struct and tutor-filtered `SELECT`, single-course lookup, and `INSERT ... RETURNING` queries.
- What you can do after
- Apply it via SQLx to derive row mapping for `Course` and return typed results from course database functions.
Read how Rust Servers, Services, and Apps explains FromRow →
Learn Haskell by Example
FromRow is a sqlite-simple type class whose instances define parsing of SQL row data into Haskell values.
- How it is used
- Parses SQLite query results into application-specific Haskell values returned by query and query_.
- How deep it goes
- Defines RowParser construction with FromField and field, then demonstrates explicit and generic instances without detailing custom parser internals.
- Examples
- Demonstrates TodoEntry parsing, query_ returning [TodoEntry], and generic FromRow and ToRow instances.
- What you can do after
- Build it from scratch by defining a FromRow instance that maps ordered SQL columns through field.
Related concepts
- SQLused by · SQL is a standardized declarative language for defining, querying, and manipulating data and structures in relational database systems.
- query_as! macroproduced by · query_as! is an SQLx compile-time macro that maps SQL query results into a specified Rust type and checks the query against the database schema.
- SQLxused by · SQLx is a Rust asynchronous toolkit for interacting with relational databases, mapping query results to Rust types, and optionally checking SQL queries at compile time.
- ToRowcontrasts with · ToRow is a sqlite-simple type class for converting Haskell values into parameters that can be bound to SQL statements.
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