Getting Started

Installation

Add the crate to your Cargo.toml:

[dependencies]
remodel-core = "0.1"

For serialization support (required if you read or write .remodel files), serde and serde_json are already re-exported through the crate's own dependencies — no extra features needed.

Prelude

Import everything you need in one line:

use remodel_core::prelude::*;

The prelude re-exports:

ConceptualModel, Entity, Attribute, Relationship, EntityId, AttributeId, RelationshipId
AttributeOwner, AttributeKind, Specialization, SpecializationKind, Union
LogicalModel, Table, Column, Constraint, ConstraintKind, ForeignKey
TableId, ColumnId
DataType, Cardinality
SqlDialect
ConvertOptions, RelationshipResolution, SpecializationStrategy
Diagnostic, Severity
Error, Result

First model

use remodel_core::prelude::*;

fn main() -> Result<()> {
    let mut m = ConceptualModel::new("library");

    // Entities
    let book   = m.add_entity("Book");
    let author = m.add_entity("Author");

    // Attributes
    m.add_primary_attribute(book,   "isbn",       DataType::Varchar(13))?;
    m.add_attribute(AttributeOwner::Entity(book),   "title",      DataType::Varchar(255))?;
    m.add_attribute(AttributeOwner::Entity(book),   "year",       DataType::Integer)?;
    m.add_primary_attribute(author, "id",         DataType::Integer)?;
    m.add_attribute(AttributeOwner::Entity(author), "full_name",  DataType::Varchar(120))?;

    // Relationship: one author writes many books (1..N ↔ 0..N)
    m.relate("wrote", author, Cardinality::OneToMany)
     .with(book, Cardinality::ZeroToMany);

    // Validate
    let diags = remodel_core::validation::validate_conceptual(&m);
    for d in &diags {
        eprintln!("[{}] {}: {}", d.severity, d.code, d.message);  // see Severity impl Display
    }

    // Convert
    let logical = m.to_logical()?;
    println!("Tables: {}", logical.tables.len());

    // Generate DDL
    let ddl = logical.to_sql(SqlDialect::Postgres);
    println!("{ddl}");

    Ok(())
}

Expected output

CREATE TABLE "Author" (
  "id" INTEGER NOT NULL,
  CONSTRAINT "pk_Author" PRIMARY KEY ("id")
);

CREATE TABLE "Book" (
  "isbn" VARCHAR(13) NOT NULL,
  "title" VARCHAR(255) NOT NULL,
  "year" INTEGER NOT NULL,
  "author_fk" INTEGER NOT NULL,
  CONSTRAINT "pk_Book" PRIMARY KEY ("isbn"),
  CONSTRAINT "fk_Book_Author" FOREIGN KEY ("author_fk")
    REFERENCES "Author" ("id")
    ON UPDATE NO ACTION ON DELETE NO ACTION
);

Error handling

All fallible operations return remodel_core::Result<T>, which is Result<T, remodel_core::Error>. The Error enum covers:

UnknownReference — an ID does not exist in the model
InvalidSpecialization — structural invariant violated
ConversionError — the model cannot be converted (e.g. missing primary key)
SerdeJson — JSON serialization/deserialization failure

match m.entity(EntityId(999)) {
    Ok(e)  => println!("{}", e.name),
    Err(e) => eprintln!("Error: {e}"),   // "unknown entity reference: 999"
}

Next steps

Conceptual Model

Full reference for entities, attributes, relationships, and more

Conversion options

Control how ER constructs map to tables and foreign keys

Validation codes

All diagnostic codes and what triggers them