Entity Relationships Documentation
This document outlines the types of relationships between entities in a DataModel, focusing on how entities are interconnected. It emphasizes that the properties used to define these relationships are common across all relationship types, offering a unified approach to modeling entity relationships.
Common Relationship Properties
Regardless of the relationship type, the following properties are used to define the specifics of how entities relate to one another:
- CascadeDelete: Indicates whether deleting an entity should automatically delete all related entities.
- LogicalId: A unique identifier for the relationship.
- Description: Provides a brief explanation of the relationship's purpose.
- FirstEntityLogicalId: Identifies the first entity in the relationship.
- SecondEntityLogicalId: Identifies the second entity in the relationship.
- Properties: Details the property mappings between the entities involved in the relationship.
Relationship Types
OneToOneRelationship
Represents a relationship where one instance of an entity is related to one instance of another entity.
OneToManyRelationship
Describes a relationship where one instance of an entity is associated with multiple instances of another entity.
ManyToManyRelationship
Indicates a relationship where multiple instances of one entity are related to multiple instances of another entity.
Examples
OneToMany Relationship Example: Author and Post
{
"RelationType": "OneToManyRelationship",
"CascadeDelete": true,
"LogicalId": "Author_Post",
"Description": "An author can write many posts.",
"FirstEntityLogicalId": "Author",
"SecondEntityLogicalId": "Post",
"Properties": [
{
"FirstEntityPropertyLogicalId": "Id",
"SecondEntityPropertyLogicalId": "AuthorId"
}
]
}ManyToMany Relationship Example: Post and Tags
{
"RelationType": "ManyToManyRelationship",
"CascadeDelete": true,
"LogicalId": "Post_Tags",
"Description": "Posts can have multiple tags, and tags can be associated with multiple posts.",
"FirstEntityLogicalId": "Post",
"SecondEntityLogicalId": "Tag",
"Properties": [
{
"FirstEntityPropertyLogicalId": "Tags",
"SecondEntityPropertyLogicalId": "Id"
}
]
}Example with Entities
"DataModel": {
"Entities": [
{
"Properties": [
{
"DataType": "String",
"MaxLength": null,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Id",
"Description": null,
"Required": false,
"IsUnique": true,
"AutoGenerate": true
},
{
"DataType": "String",
"MaxLength": 250,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Name",
"Description": "Name",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
},
{
"DataType": "Enum",
"EnumTyeLogicalId": "RoleType",
"LogicalId": "Role",
"Description": "Role ",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
},
{
"DataType": "Boolean",
"DefaultValue": false,
"LogicalId": "Active",
"Description": "Active",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
}
],
"LogicalId": "Author",
"Description": "Author",
"ExtensionsData": null
},
{
"Properties": [
{
"DataType": "Int32",
"MinValue": null,
"MaxValue": null,
"DefaultValue": null,
"LogicalId": "Id",
"Description": null,
"Required": false,
"IsUnique": true,
"AutoGenerate": true
},
{
"DataType": "String",
"MaxLength": 250,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Name",
"Description": "tag name",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
}
],
"LogicalId": "Tag",
"Description": "Tag",
"ExtensionsData": null
},
{
"Properties": [
{
"DataType": "String",
"MaxLength": null,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Id",
"Description": null,
"Required": false,
"IsUnique": true,
"AutoGenerate": true
},
{
"DataType": "String",
"MaxLength": 250,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Title",
"Description": "Title",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
},
{
"DataType": "String",
"MaxLength": 5000,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "Content",
"Description": "Content",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
},
{
"DataType": "String",
"MaxLength": null,
"DefaultValue": null,
"RegularExpression": null,
"LogicalId": "AuthorId",
"Description": "AuthorId",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
},
{
"DataType": "PrimitiveArray",
"ValueType": "String",
"LogicalId": "Tags",
"Description": "Tags",
"Required": true,
"IsUnique": false,
"AutoGenerate": false
}
],
"LogicalId": "Post",
"Description": "Post",
"ExtensionsData": null
}
],
"Relationships": [
{
"RelationType": "OneToManyRelationship",
"CascadeDelete": true,
"LogicalId": "Author_Post",
"Description": "content of the question template",
"FirstEntityLogicalId": "Author",
"SecondEntityLogicalId": "Post",
"Properties": [
{
"FirstEntityPropertyLogicalId": "Id",
"SecondEntityPropertyLogicalId": "AuthorId"
}
],
"ExtensionsData": null
},
{
"RelationType": "ManyToManyRelationship",
"CascadeDelete": true,
"LogicalId": "Post_Tags",
"Description": "post tags",
"FirstEntityLogicalId": "Post",
"SecondEntityLogicalId": "Tag",
"Properties": [
{
"FirstEntityPropertyLogicalId": "Tags",
"SecondEntityPropertyLogicalId": "Id"
}
],
"ExtensionsData": null
}
],
"LogicalId": "Blog",
"Description": "Blog Example",
"ExtensionsData": null
}