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Entity Relationship Diagram (ERD)

Visualize your MongoDB database schema with an interactive Entity Relationship Diagram showing collections and their fields.

Getting Started​

Connect to your MongoDB database and select a database. The ERD automatically generates a visual representation of all collections and their field structures.

ERD Features​

Collection Nodes​

Each collection is displayed as a node:

  • Collection name as header
  • Field list with types
  • Document count badge
  • Click to select

Field Information​

See field names and types for each collection:

  • Field name
  • Inferred data type
  • Required/optional indicator
  • Nested object indicator

Document Counts​

View approximate document counts per collection:

  • Shown on collection node
  • Helps identify large/small collections
  • Updates on refresh

Interactive Layout​

Drag nodes to reorganize the diagram:

  • Click and drag collection nodes
  • Arrange for best visibility
  • Layout persists during session

Zoom and Pan​

Navigate large schemas easily:

  • Scroll to zoom in/out
  • Click and drag background to pan
  • Fit all button to view entire diagram

Schema Analysis​

The ERD analyzes sample documents from each collection to infer field types and structures:

Field Type Detection​

  • String, Number, Boolean, Date
  • ObjectId (potential references)
  • Array (with element types)
  • Nested Object (with sub-fields)

Nested Structures​

Nested objects and arrays are represented in the field list:

address: Object
  ├── street: String
  ├── city: String
  └── zip: String
tags: Array<String>

Reference Detection​

Potential relationships between collections:

  • ObjectId fields that may reference other collections
  • Field names suggesting relationships (userId, orderId)
  • Matching patterns across collections

Using the ERD​

Understand Database Structure​

Before building forms:

  • See all collections at a glance
  • Understand data organization
  • Identify main entities

Identify Relationships​

Find connections between collections:

  • Foreign key patterns
  • Reference fields
  • Join opportunities

Discover Available Fields​

Before building forms:

  • See all fields in a collection
  • Understand field types
  • Plan form field mappings
tip

The ERD updates automatically when you change databases. Use it as a reference when configuring lookup fields in your forms.

ERD Controls​

Refresh​

Reload schema from database:

  • Gets latest structure
  • Updates document counts
  • Refreshes field types

Zoom Controls​

  • Zoom In (+) - Closer view
  • Zoom Out (-) - Wider view
  • Fit All - Show entire diagram
  • Reset - Default zoom level

Layout Options​

  • Auto Layout - Arrange nodes automatically
  • Horizontal - Left-to-right layout
  • Vertical - Top-to-bottom layout

Filter​

Filter visible collections:

  • Search by name
  • Show/hide specific collections
  • Focus on relevant tables

Collection Details​

Click on a collection to see details:

Statistics​

  • Document count
  • Average document size
  • Index information
  • Storage size

Schema​

  • All fields detected
  • Type distribution
  • Optional/required fields
  • Nested structure

Sample Data​

  • View sample documents
  • See actual values
  • Understand data patterns

Export Options​

Export Image​

Save ERD as an image:

  • PNG format
  • High resolution
  • Include/exclude details

Export Schema​

Export schema as JSON:

{
  "collections": {
    "users": {
      "fields": {
        "name": "String",
        "email": "String",
        "createdAt": "Date"
      }
    }
  }
}

Best Practices​

  1. Refresh regularly - Schema may change
  2. Note relationships - Track foreign keys
  3. Document discoveries - Note unexpected structures
  4. Use for planning - Before building forms
  5. Share with team - Export for documentation

Limitations​

Sampling-Based​

Schema is inferred from samples:

  • May miss rare fields
  • Types based on observed values
  • Refresh for better coverage

No Enforced Relationships​

MongoDB doesn't enforce relationships:

  • ERD shows inferred connections
  • Verify relationships manually
  • Reference patterns may vary

Next Steps​