Connection String not found WPF Entity Framework

Question

I am in a WPF project using some MVVM practices, I am using Entity Framework database first and the Connection string is already in the app.config, I have already followed all the procedures I have read in several questions but in the view appears this message in Datacontext

Below the connectionstring that is already in the app.config

 <add name="TimerEntities" connectionString="metadata=res://*/Timer.csdl|res://*/Timer.ssdl|res://*/Timer.msl;provider=System.Data.SqlServerCe.4.0;provider connection string=&quot;Data Source=C:\Users\Angelica\Documents\DB\Timer.sdf;Max Database Size=4091&quot;"
 providerName="System.Data.EntityClient" />

---

The Context of the Database

using System;
using System.Data.Entity;
using System.Data.Entity.Infrastructure;

public partial class TimerEntities : DbContext
{
    public TimerEntities()
        : base("name=TimerEntities")
    {
    }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        throw new UnintentionalCodeFirstException();
    }

    public virtual DbSet<CAIXA> CAIXAS { get; set; }
    public virtual DbSet<CLIENTE> CLIENTES { get; set; }
    public virtual DbSet<ORDEM> ORDEM { get; set; }
    public virtual DbSet<PACOTE> PACOTES { get; set; }
    public virtual DbSet<TEMPO> TEMPOS { get; set; }
}

---

Procedures I’ve done that haven’t worked:

1. Remove "name" from Context;
2. Put the Connection string in another file config and link to app.config;
3. Comment on throw new UnintentionalCodeFirstException();;

---

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
    <section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
    <!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
  </configSections>
    <connectionStrings>
      <add name="TimerEntities" connectionString="metadata=res://*/Timer.csdl|res://*/Timer.ssdl|res://*/Timer.msl;provider=System.Data.SqlServerCe.4.0;provider connection string=&quot;Data Source=C:\Users\Angelica\Documents\DB\Timer.sdf;Max Database Size=4091&quot;"
     providerName="System.Data.EntityClient" />
  </connectionStrings>
  <startup>
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.6" />
  </startup>
  <entityFramework>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlCeConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="System.Data.SqlServerCe.4.0" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
      <provider invariantName="System.Data.SqlServerCe.4.0" type="System.Data.Entity.SqlServerCompact.SqlCeProviderServices, EntityFramework.SqlServerCompact" />
    </providers>
  </entityFramework>
  <system.data>
    <DbProviderFactories>
      <remove invariant="System.Data.SqlServerCe.4.0" />
      <add name="Microsoft SQL Server Compact Data Provider 4.0" invariant="System.Data.SqlServerCe.4.0" description=".NET Framework Data Provider for Microsoft SQL Server Compact" type="System.Data.SqlServerCe.SqlCeProviderFactory, System.Data.SqlServerCe, Version=4.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
    </DbProviderFactories>
  </system.data>
</configuration>

Answer 1

This seems to me bad project setup. The configuration file is ok but apparently not being properly recognized.

There are a few things you can do to get around the problem quickly:

1. Not using name=TimerEntities in the context builder

Would look like this:

public TimerEntities()
    : base("TimerEntities")
{
}

2. Moving on to Connection string directly to the base builder

Would look like this:

public TimerEntities()
    : base("metadata=res://*/Timer.csdl|res://*/Timer.ssdl|res://*/Timer.msl;provider=System.Data.SqlServerCe.4.0;provider connection string="Data Source=C:\Users\Angelica\Documents\DB\Timer.sdf;Max Database Size=4091"")
{
}

The latter is not exactly recommended. Only use in case of urgency.