ewl-data-access

name: ewl-data-access description: EWL generated data access layer including table retrievals, modifications, row constants, sequences, and caching

Overview

The Development Utility generates data-access classes from your database schema. These live in Generated Code\ folders and must never be edited directly. You can extend them with hand-written partial class files.

Run sync after any schema change to regenerate.

Table retrievals

Generated *TableRetrieval classes provide typed read access:

// Get all rows
var rows = ServiceOrdersTableRetrieval.GetRows();

// Get rows matching a condition
var rows = ServiceOrdersTableRetrieval.GetRows(
    new ServiceOrdersTableEqualityConditions.CustomerId( customerId ) );

// Get a single row by primary key (throws if not found)
var row = ServiceOrdersTableRetrieval.GetRowMatchingPk( serviceOrderId );

// Try to get a single row (returns false if not found)
if( ServiceOrdersTableRetrieval.TryGetRowMatchingPk( id, out var row ) )
    // use row

// For small/cached tables
var allRows = ServiceTypesTableRetrieval.GetAllRows();

Row objects expose typed properties for each column (e.g. row.CustomerName, row.ServiceTypeId).

Modifications

Generated *Modification classes provide insert, update, and delete:

// Insert
var mod = ServiceOrdersModification.CreateForInsert();
mod.ServiceOrderId = MainSequence.GetNextValue();
mod.CustomerName = "Jane Doe";
mod.CustomerEmail = "jane@example.com";
mod.Execute();

// Update from a condition
var mod = UsersModification.CreateForUpdate(
    new UsersTableEqualityConditions.UserId( userId ) );
mod.EmailAddress = newEmail;
mod.Execute();

// Update from a row (common pattern)
var mod = serviceOrderRow.ToModification();
mod.CustomerName = "Updated Name";
mod.Execute();

// Delete
ServiceOrdersModification.DeleteRows(
    new ServiceOrdersTableEqualityConditions.ServiceOrderId( id ) );

// Insert with all columns in one call
UsersModification.InsertRow( userId, email, roleId, 0, null, null, null, null, null, "" );

Primary keys

All new entity IDs use the main sequence, never auto-increment:

mod.ServiceOrderId = MainSequence.GetNextValue();

Row constants

Lookup tables declared in Development.xml as rowConstantTables produce generated constant classes:

UserRolesRows.Administrator
ServiceTypesRows.GeneralService
EmailTemplatesRows.Reminder

Configure in Development.xml:

<database>
    <rowConstantTables>
        <table tableName="UserRoles" nameColumn="RoleName" valueColumn="UserRoleId" />
    </rowConstantTables>
    <SmallTables>
        <Table>UserRoles</Table>
    </SmallTables>
</database>

Form items from modifications

Modification objects generate form controls directly. This is the primary way forms are built in EWL:

mod.GetCustomerNameFormItem( false )
mod.GetCustomerEmailFormItem( false )
mod.GetServiceTypeIdDropDownFormItem( DropDownSetup.Create( items ), "" )
mod.GetNotesFormItem( true, controlSetup: TextControlSetup.Create( numberOfRows: 4 ) )

The first boolean parameter controls whether the field is optional. Control types are inferred from column names (e.g. "Email" columns get email controls).

Extending generated classes

Create partial classes alongside the .ewlt.cs files to add custom logic:

partial class UsersModification {
    static partial void populateConstraintNamesToViolationErrorMessages(
            Dictionary<string, string> constraintNamesToViolationErrorMessages ) {
        constraintNamesToViolationErrorMessages.Add(
            "UsersEmailAddressUnique", "A user with this email address already exists." );
    }
}

Available partial methods for modifications: preInsert, postInsert, preUpdate, postUpdate, preDelete, populateConstraintNamesToViolationErrorMessages.

For retrievals, add extension methods or computed properties on the Row class:

public static IEnumerable<Row> Active( this IEnumerable<Row> rows ) =>
    rows.Where( i => i.IsActive );

Application-level table caching

Create a companion YourDataTableEwlModifications table containing only the main table's primary key column(s). This enables change-tracking cache invalidation so that large queries become tiny queries while never returning stale data.

Requirements:

• All modifications go through EWL-generated Modification classes
• Database transactions use snapshot isolation

Revision history

Tables in revisionHistoryTables in Development.xml get automatic versioning. Retrieval and modification classes are revision-history-aware: retrievals return only the latest revision, and modifications automatically create new revisions.

Custom retrieval queries are NOT revision-history-aware; you must join:

SELECT s.* FROM SomeTableRevisions s
JOIN Revisions r ON r.RevisionId = s.SomeTableRevisionId
    AND r.LatestRevisionId = r.RevisionId