Writing a bridge · Docs — DomainCraft

A bridge is a directory of template files plus a bridge.yaml manifest. Bridges are fully decoupled from the Go core — no Go code is required to add a language.

Resolution

The CLI resolves a bridge in this order:

1. Local path → used directly.
2. Registry ID (e.g. csharp-restful) → checked in ~/.domaincraft/bridges/, cloned if needed.
3. owner/repo GitHub shorthand → cloned.
4. Empty + interactive terminal → selection menu.

bridge.yaml

name: csharp-restful
description: C# REST API bridge (EF Core + PostgreSQL + JWT)
version: "1.0.0"
output_dir: generated
helpers: templates/_helpers.cs.tmpl

registry_url: "https://api.nuget.org/v3-flatcontainer/{id}/index.json"

registry_packages:
  ef_core: Microsoft.EntityFrameworkCore
  jwt_bearer: Microsoft.AspNetCore.Authentication.JwtBearer

migrations:
  enabled: true
  commands:
    - "dotnet ef migrations add InitialCreate --project src/Infrastructure ..."
    - "dotnet ef database update --project src/Infrastructure ..."

supports:
  - api_style: rest
  - database: postgresql
  - auth: jwt
  - multi_tenancy: "none"

• registry_url / registry_packages — optional package registry used to auto-resolve latest stable versions ({id} is replaced with the lowercased package ID).
• migrations — commands the core runs when invoked with domaincraft generate --migrate.
• supports — documented configurations the bridge targets.

Templates

Each template spec has:

templates:
  - for: entity            # entity = once per entity; project = once per project
    source: templates/entity.cs.tmpl
    target: "src/Domain/Entities/{{ .Entity.Name }}.cs"
    when: hasEnums         # optional condition
    overwrite: false       # optional: scaffold once, developer owns the file
    delimiters: ["<<", ">>"]  # optional: for JSX/TSX bridges

when conditions

• hasSeed, hasEnums, hasPermissions, hasOwnerTokens, hasAuth, hasSchemaRenames
• hasAddon:dapr / notHasAddon:dapr
• when: hasAuth only renders when auth is enabled.
• when: hasSchemaRenames only renders when an entity or field declares an old_name hint — used to emit data-preserving RenameTable/RenameColumn migrations.

overwrite: false

Creates a file only once; the developer owns it afterwards. The renderer skips existing files and records them in the manifest as Custom: true. The migration engine uses this to protect developer-owned files when an entity is deleted, renamed or its types change. Rule for bridge authors: split Core (always regenerated) and Custom (overwrite: false) code — put generated logic behind interfaces and scaffold the developer-owned implementation only once (e.g. partial classes in C#).

Template context

Templates receive a RenderContext with .Project, .Entity, .Bridge, .Packages. Entity methods: .HasFeature("audit"), .HasAudit(), .HasSoftDelete(), .NonRelationFields(), .RelationFields(). Field methods: .IsArray(), .HasValidation(name), .ValidationValue(name). Use {{ .Entity.Name }}, {{ pluralize .Entity.Name }}, {{ fkName .Name | pascalcase }} directly.

type_mappings.yaml

Language-specific type mapping, loaded at runtime — the Go core stays language-agnostic:

types:
  uuid: "Guid"
  string: "string"
  decimal: "decimal"

value_types: ["int", "long", "bool", "DateTime", "Guid"]

behaviors:
  cascade: "Cascade"
  set_null: "SetNull"

array_format: "List<%s>"
nullable_format: "?"
enum_nullable: true

These power the languageType, isValueType, deleteBehaviorName and (admin) inputType template functions.

Constraints

• Templates must use {{- / -}} whitespace trimming for clean output.
• All map iteration that affects output must be sorted — Go maps are randomized; two runs on the same domain.yaml must produce identical output.
• Feature fields (createdAt, updatedAt, …) are auto-injected — filter them with isFeatureField.
• For JSX/TSX bridges, remove inline style={{ }} and set delimiters: ["<<", ">>"] to avoid conflicts with Go template delimiters.