AddRelation Method

Overview

The AddRelation method registers a parent / child relationship in IDataSet.Relations.

In the POCO DataSet core model, relations are stored as metadata (they do not automatically enforce constraints). Once a relation is registered, you can use navigation helpers like GetChildRows and TryGetParentRow, or validate referential integrity using ValidateRelations / EnsureRelationsValid.

Declaration

/// <summary>
/// Adds relation between parent and child tables in a data set
/// IDataSet interface implementation
/// </summary>
/// <param name="relationName">Relation name</param>
/// <param name="parentTableName">Parent table name</param>
/// <param name="parentColumnName">Parent column name</param>
/// <param name="childTableName">Child table name</param>
/// <param name="childColumnName">Child column name</param>
IDataRelation AddRelation(string relationName, string parentTableName, string parentColumnName, string childTableName, string childColumnName)

/// <summary>
/// Adds relation between parent and child tables in a data set using composite keys
/// IDataSet interface implementation
/// </summary>
/// <param name="relationName">Relation name</param>
/// <param name="parentTableName">Parent table name</param>
/// <param name="parentColumnNames">Parent column names</param>
/// <param name="childTableName">Child table name</param>
/// <param name="childColumnNames">Child column names</param>
public static void AddRelation(string relationName, string parentTableName, IList<string> parentColumnNames, string childTableName, IList<string> childColumnNames)

Namespace and Assembly

Namespace: PocoDataSet.Data
Assembly: PocoDataSet.Data.dll

Behavior

• If dataSet is null, the method returns without doing anything.
• If dataSet.Relations is null, it is initialized to an empty list.
• If a relation with the same name already exists, the method does nothing.
• Stores the relation metadata (parent table/columns, child table/columns) in IDataSet.Relations.

Usage Example

Simple primary and foreign keys example

// 1. Create new data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Add parent Customer table with Id primary key
IDataTable customerDataTable = dataSet.AddNewTable("Customer");
customerDataTable.AddColumn("Id", DataTypeNames.INT32);
customerDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Add child Order table with CustomerId foreign key
IDataTable orderDataTable = dataSet.AddNewTable("Order");
orderDataTable.AddColumn("Id", DataTypeNames.INT32);
orderDataTable.AddColumn("CustomerId", DataTypeNames.INT32, false, false, true);
orderDataTable.AddColumn("Status", DataTypeNames.STRING);

// 4. Add relation between Customer and Order tables: Customer.Id -> Order.CustomerId
dataSet.AddRelation("CustomerOrder", "Customer", "Id", "Order", "CustomerId");

// Insert data
IDataRow customerDataRow = customerDataTable.AddNewRow();
customerDataRow["Id"] = 1;
customerDataRow["Name"] = "Acme";
customerDataTable.AcceptChanges();

IDataRow orderDataRow = orderDataTable.AddNewRow();
orderDataRow["Id"] = 1;
orderDataRow["CustomerId"] = 1;
orderDataRow["Status"] = "Open";
orderDataTable.AcceptChanges();

// Now relation navigation works (see GetChildRows / TryGetParentRow docs).
bool hasRelation = dataSet.ContainsRelation("CustomerOrder"); // true

Composite primary and foreign keys example

// 1. Create new data set
IDataSet dataSet = DataSetFactory.CreateDataSet();

// 2. Add parent Customer table with Code1 and Code2 primary keys
IDataTable customerDataTable = dataSet.AddNewTable("Customer");
customerDataTable.AddColumn("Code1", DataTypeNames.STRING, false, true);
customerDataTable.AddColumn("Code2", DataTypeNames.STRING, false, true);
customerDataTable.AddColumn("Name", DataTypeNames.STRING);

// 3. Add child Order table with CustomerCode1 and CustomerCode2 composite foreign key
IDataTable orderDataTable = dataSet.AddNewTable("Order");
orderDataTable.AddColumn("Id", DataTypeNames.INT32, false, true);
orderDataTable.AddColumn("CustomerCode1", DataTypeNames.STRING, false, false, true);
orderDataTable.AddColumn("CustomerCode2", DataTypeNames.STRING, false, false, true);
orderDataTable.AddColumn("Status", DataTypeNames.STRING);

// Add relation between Customer and Order tables
// Customer.Code1 -> Order.CustomerCode1
// Customer.Code2 -> Order.CustomerCode2
dataSet.AddRelation("CustomerOrder", "Customer", new List<string> { "Code1", "Code2" }, "Order", new List<string> { "CustomerCode1", "CustomerCode2" });

// Insert data
IDataRow customerDataRow = customerDataTable.AddNewRow();
customerDataRow["Code1"] = "Acme";
customerDataRow["Code2"] = "Group";
customerDataRow["Name"] = "Performance";
customerDataTable.AcceptChanges();

IDataRow orderDataRow = orderDataTable.AddNewRow();
orderDataRow["OrderId"] = 1;
orderDataRow["CustomerCode1"] = "Acme";
orderDataRow["CustomerCode2"] = "Group";
orderDataRow["Status"] = "Open";
orderDataTable.AcceptChanges();

// Now relation navigation works (see GetChildRows / TryGetParentRow docs).
bool hasRelation = dataSet.ContainsRelation("CustomerOrder"); // true

 

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