FluentData load references

Introduction

FluentData is an opensource library ( https://fluentdata.codeplex.com/ ) that enables you to access databases using direct query without to have a mapped entity framework, in fact it can work using the C# 4.0 dynamics.

I developed a simple extension method to allow you easily add the navigating properties to gathered data ( https://github.com/devel0/Lib0/tree/master/Lib0.Data.FluentData ).

Test database

The simple database that I used has two tables and a foreign key that let you navigate from the "user_entries" table to the "contact_detail" table through the "id_contact_detail" foreign key.

Test app

The test application is composed by a datagrid that lists the user_entries ids and a form detail which shows the firstname and lastname fields of the related record.

XAML part

<!--#region Master/Detail -->
        <Grid Grid.Row="1">
            <Grid.ColumnDefinitions>
                <ColumnDefinition/>
                <ColumnDefinition/>
            </Grid.ColumnDefinitions>
            
            <!--#region Master -->
            <DataGrid x:Name="MasterDataGrid" IsReadOnly="True">
                <DataGrid.Columns>
                    <DataGridTextColumn Header="ID" Binding="{Binding id}"/>
                </DataGrid.Columns>
            </DataGrid>
            <!--#endregion-->

            <!--#region Detail -->
            <Grid Grid.Column="1" x:Name="DetailDataGrid" 
                  DataContextChanged="DetailDataGrid_DataContextChanged"
                  DataContext="{Binding ElementName=MasterDataGrid, Path=SelectedItem}">
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto"/>
                    <RowDefinition Height="Auto"/>                    
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>
                
                <TextBlock Grid.Row="0" Grid.Column="0" Text="Firstname:" VerticalAlignment="Center"/>
                <TextBox Grid.Row="0" Grid.Column="1" Text="{Binding contact_detail.firstname, Mode=TwoWay}"/>
                
                <TextBlock Grid.Row="1" Grid.Column="0" Text="Lastname:" VerticalAlignment="Center"/>
                <TextBox Grid.Row="1" Grid.Column="1" Text="{Binding contact_detail.lastname, Mode=TwoWay}"/>
            </Grid>
            <!--#endregion-->
        </Grid>
        <!--#endregion-->

Code part

ctx = new DbContext().ConnectionString(ConnectionStringTbox.Text, new PostgreSqlProvider());

var q = ctx.Sql("select * from user_entries").QueryMany<dynamic>();

q.LoadReferences(ctx,                
    "contact_detail",
    k => k.id_contact_detail,                
    k => k.id
    );           

MasterDataGrid.ItemsSource = q.ToList();

The extension method "LoadReferences" extends given dynamic objects that comes from the QueryMany with the property "contact_detail" that is the object gathered from the database using the foreign key.

Considerations

The extension library discussed is mostly an initial act for a deeper investigation about what can be done to make the use of the FluentData library more useful compared to the Entity Framework.

Roadmap :

• better management of loading references
• use of custom where to restrict the result set
• use of join instead of load all records
• lazy load of records
• management of changeset
• listen to dynamics using PropertyChanged

---

FluentData lazy loader by Lorenzo Delana is licensed under a Creative Commons Attribution 4.0 International License.