Data Model¶

Entity-Relationship Diagram¶

erDiagram
    Package ||--o{ Package : "parent_package"
    Package ||--o{ Class : "contains"
    Package ||--o{ Enumeration : "contains"
    Package ||--o{ Diagram : "contains"

    Class ||--o{ Attribute : "has"
    Class ||--o{ Association : "src_class"
    Class ||--o{ Association : "dst_class"
    Class ||--o{ Generalization : "superclass"
    Class ||--o{ Generalization : "subclass"

    Enumeration ||--o{ EnumerationLiteral : "has"
    Attribute |o--o| Enumeration : "optional type"

    Diagram }o--o{ Class : "DiagramClass"
    Diagram }o--o{ Enumeration : "DiagramEnumeration"
    Diagram }o--o{ Association : "DiagramAssociation"
    Diagram }o--o{ Generalization : "DiagramGeneralization"

    Package {
        string id PK
        string schema_id
        string name
        string parent_package_id FK
        string definitie
        string bron
        string toelichting
        string author
        string version
        string phase
        string status
        string uri
        string stereotype
        datetime created
        datetime modified
    }

    Class {
        string id PK
        string schema_id
        string name
        string package_id FK
        boolean is_datatype
        string definitie
        string bron
        string toelichting
        string author
        string version
        string phase
        string status
        string uri
        string stereotype
    }

    Attribute {
        string id PK
        string schema_id
        string name
        string clazz_id FK
        string primitive
        string enumeratie_id FK
        string definitie
        string bron
        string toelichting
    }

    Association {
        string id PK
        string schema_id
        string name
        string src_class_id FK
        string dst_class_id FK
        string src_mult_start
        string src_mult_end
        string dst_mult_start
        string dst_mult_end
        string src_role
        string dst_role
        string src_documentation
        string dst_documentation
    }

    Generalization {
        string id PK
        string schema_id
        string name
        string superclass_id FK
        string subclass_id FK
    }

    Enumeration {
        string id PK
        string schema_id
        string name
        string package_id FK
        string definitie
        string bron
    }

    EnumerationLiteral {
        string id PK
        string schema_id
        string name
        string enumeratie_id FK
    }

    Diagram {
        string id PK
        string schema_id
        string name
        string package_id FK
    }

Model Details¶

Package¶

Container for classes and enumerations. Packages form a hierarchy via self-referencing parent_package_id.

Important methods:

get_classes() — All classes in this package
get_enumerations() — All enumerations
is_model() — Is this a top-level model package?
get_classes_in_model() — All classes recursively in the hierarchy
get_copy() — Deep copy of the package and all children

Class¶

UML Class entity with attributes and relationships.

Relationships:

package — Parent package
attributes — 1:N relationship with Attribute
outgoing_associations — Associations where this class is the source
incoming_associations — Associations where this class is the target
superclasses — Generalizations as subclass
subclasses — Generalizations as superclass

Important methods:

get_attribute_by_name() — Look up attribute by name
copy_attributes() — Copy attributes to another class
get_copy() — Deep copy including attributes

Attribute¶

Property of a Class. Can have a primitive type (primitive as string) or a reference to an Enumeration.

Association¶

Bidirectional relationship between two Classes with multiplicities and role names.

graph LR
    A["Class A<br/>(src)"] -->|"src_role<br/>src_mult"| R["Association"]
    R -->|"dst_role<br/>dst_mult"| B["Class B<br/>(dst)"]

Generalization¶

Inheritance relationship between two classes. Contains a materialize() method that copies attributes from the superclass to the subclass.

Enumeration & EnumerationLiteral¶

Enumeration type with named values. EnumerationLiteral contains the individual values.

Diagram¶

Visual diagram that references classes, enumerations, associations and generalizations via junction tables.

Mixin Structure¶

All entities share fields via mixins:

Mixin	Fields	Used by
`UML_Generic`	id, schema_id, name, definitie, bron, toelichting, created, modified, stereotype	All entities
`UMLBase`	author, version, phase, status, uri, visibility, alias	Package, Class, Attribute, etc.
`UMLTagsClazz`	MIM tags, GEMMA tags, history indicators	Class
`UMLTagsAttr`	Attribute-specific tags	Attribute
`UMLTagsAssoc`	Association-specific tags	Association

Schema Isolation: Reading the Same Model Multiple Times¶

One of the most powerful features of crunch_uml is that you can read the same model multiple times in different schemas within the same database. All tables contain a schema_id column that enables this isolation.

How Does It Work?¶

Each schema is like a separate "compartment" in the database. When you import or transform a model, you specify with -sch which schema the data should go into. Entities in one schema are completely separate from entities in another — they coexist in the same database but do not overlap.

graph TB
    DB[("crunch_uml.db<br/>━━━━━━━━━━━━<br/>One physical database")]

    subgraph schema_default["Schema: default"]
        D1["All packages"]
        D2["All classes"]
        D3["All relationships"]
    end

    subgraph schema_v1["Schema: v1.0"]
        V1["Core model v1"]
    end

    subgraph schema_v2["Schema: v2.0"]
        V2["Core model v2"]
    end

    subgraph schema_en["Schema: translation_en"]
        EN["English version"]
    end

    DB --> schema_default & schema_v1 & schema_v2 & schema_en

    style DB fill:#1a5276,color:#fff
    style schema_default fill:#dae8fc,stroke:#6c8ebf
    style schema_v1 fill:#d5e8d4,stroke:#82b366
    style schema_v2 fill:#d5e8d4,stroke:#82b366
    style schema_en fill:#fff2cc,stroke:#d6b656

Typical Applications¶

Version Comparison — Import two versions of the same model (each in its own schema) and use the diff_md renderer to automatically report the differences:

# Version 2.0 in default schema (already imported)
crunch_uml transform -ttp copy -sch_to version_2 -rt_pkg ROOT

# Version 1.0 in separate schema
crunch_uml -sch v1_raw import -f model_v1.xmi -t eaxmi
crunch_uml transform -ttp copy -sch_from v1_raw -sch_to version_1 -rt_pkg ROOT

# Generate diff
crunch_uml -sch version_1 export -t diff_md -f diff.md \
    --compare_schema_name version_2 --compare_title "v1 → v2"

Multi-Language — Copy the model to a translation schema and import translations:

crunch_uml transform -ttp copy -sch_to translation_en -rt_pkg ROOT
crunch_uml -sch translation_en import -f translations.json -t i18n --language en

Partial Models — Copy only a specific package (and everything below it) to a working schema:

crunch_uml transform -ttp copy -sch_to partial_model -rt_pkg EAPK_SUBPACKAGE_ID

Experimentation — Copy to a test schema, experiment with materialization of inheritance, and export — without touching the original:

crunch_uml transform -ttp copy -sch_to experiment -rt_pkg ROOT -m_gen True
crunch_uml -sch experiment export -t xlsx -f experiment.xlsx

Technical Implementation¶

The Schema class in schema.py forms the wrapper. All CRUD operations run through the Schema class, which automatically filters by schema_id:

schema = Schema(database, "my_schema")
schema.get_all_classes()       # Only classes from "my_schema"
schema.save(obj)               # Writes with schema_id = "my_schema"
schema.clean()                 # Deletes everything in "my_schema"

Because schema_id is on every table (packages, classes, attributes, associations, generalizations, enumerations, diagrams), the isolation is complete. There is no risk that data from one schema affects the other.