d365fo-model-architecture

name	d365fo-model-architecture
description	Use when user asks about D365FO model structure, dependencies, coupling, naming conventions, or impact analysis. "what models depend on ApplicationSuite", "show coupling metrics for our ISV layer", "which objects will be affected if I change SalesTable", "are there circular model dependencies", "validate naming convention for our custom model", "how many objects are in FleetManagement model", "analyze impact of adding a field to CustTable", "stats for all custom models"
license	MIT
metadata	{"version":"1.0"}

D365FO Model Architecture & Impact Analysis

Analyse model structure, dependency coupling, object counts, naming conventions, and change impact before making architectural decisions or writing a technical spec.

When to use

• User is evaluating the risk and blast radius of a change to a base object
• User wants to understand model dependency chains before adding a new model reference
• User is performing a code quality or coupling review of an ISV or custom model layer
• User wants to validate that new objects follow D365FO naming conventions
• User needs object counts and statistics for project estimation or documentation

Workflow

1. List all models. Call list_models() — returns all indexed models with their publisher, layer, and whether they are custom vs. standard.

2. Get model statistics. Call stats(model) — returns object counts by type (tables, classes, forms, etc.) for a specific model or all custom models.

3. Analyse dependencies. Call get_model_dependencies(modelName) — returns dependsOn (what this model references) and dependedBy (what references it).

4. Check coupling. Call models_coupling(topN, onlyCycles) — returns fan-in, fan-out, instability, and detected dependency cycles across all models. Use onlyCycles: true to focus only on circular dependencies (these block upgrades).

5. Analyse change impact. Call analyze_impact(target) — given an object name, returns all objects that directly or transitively reference it, scoped to custom models. Use this before modifying a widely-used base class or table.

6. Validate naming. Call validate_object_naming(name, type) — checks the name against D365FO naming convention rules (prefix requirements, casing, reserved words).

7. Run BP lint. Call lint(categories, onlyCustomModels: true) — runs best-practice checks (missing indexes, EDT-less string fields, unnamed extensions) across custom models only.

8. Multi-object search. Call batch_search(queries[]) — resolves multiple object names in a single call; useful for validating a list of objects from an SFD.

Output Format

Model dependency

FleetManagement
  dependsOn  : ApplicationSuite, ApplicationPlatform
  dependedBy : FleetManagementExtension, ContosoCustModel

Coupling metrics

Model	Fan-in	Fan-out	Instability	Cycles
ContosoCustModel	0	5	1.00 (leaf)	None
ApplicationSuite	312	8	0.03 (stable)	None
ISVModelA	4	4	0.50	⚠ cycle with ISVModelB

Instability = fan-out / (fan-in + fan-out). 1.0 = leaf (nothing depends on it), 0.0 = core (everything depends on it). Custom models should target instability ≥ 0.8.

Impact analysis

Object affected	Type	Model	Reference path
SalesConfirmDP	Class	ContosoCustModel	CoC → SalesTable
ContosoSalesTableExt	TableExt	ContosoCustModel	TableExtension of SalesTable

BP lint findings

Rule	Severity	Object	Detail
string-without-edt	Warning	ContosoSalesTableExt.MyField	str field has no EDT
table-no-index	Warning	ContosoTmpTable	No clustered index defined

Notes

• Run coupling analysis before adding a new dependsOn entry to a model — adding a dependency on a high fan-in model (instability near 0) makes your model harder to upgrade independently.
• analyze_impact scopes to the indexed metadata — it does not parse unindexed X++ source. For very new customisations, re-run d365fo index refresh first.
• Circular model dependencies (onlyCycles: true) are blocked by the D365FO compiler and will cause build failures — resolve before committing.
• Naming convention: custom objects must be prefixed with your model's prefix (e.g. Contoso). validate_object_naming checks prefix, casing, and reserved words.