New Post: Create MigrationSqlGenerator for PostgreSQL

public Configuration()
    {
        AutomaticMigrationsEnabled = false;
        SetSqlGenerator("Npgsql", new PostgreSqlMigrationSqlGenerator());
    }

From the Package Manager Console, I execute the command "Update-Database -Verbose". All the migrations are executed correctly and It create the Schema and all the Tables (including the __MigrationHistory table) perfectly. At the end of creation, It show me this error:

System.FormatException: Input string was not in a correct format.
   at System.Number.StringToNumber(String str, NumberStyles options, NumberBuffer& number, NumberFormatInfo info, Boolean parseDecimal)
   at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo info)
   at System.Convert.ToInt32(String value)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.BuildColumnModel(XElement property, String entitySetName, ModelMetadata modelMetadata)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.BuildAlterColumnOperation(String table, XElement targetProperty, String targetEntitySetName, ModelMetadata targetModelMetadata, XElement sourceProperty, String sourceEntitySetName, ModelMetadata sourceModelMetadata)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.<FindChangedColumns>b__ef(<>f__AnonymousType1d`2 <>h__TransparentIdentifiere5)
   at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at System.Data.Entity.Migrations.Infrastructure.EdmModelDiffer.Diff(XDocument sourceModel, XDocument targetModel, String connectionString)
   at System.Data.Entity.Migrations.DbMigrator.IsModelOutOfDate(XDocument model, DbMigration lastMigration)
   at System.Data.Entity.Migrations.DbMigrator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.Infrastructure.MigratorLoggingDecorator.Upgrade(IEnumerable`1 pendingMigrations, String targetMigrationId, String lastMigrationId)
   at System.Data.Entity.Migrations.DbMigrator.Update(String targetMigration)
   at System.Data.Entity.Migrations.Infrastructure.MigratorBase.Update(String targetMigration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.UpdateRunner.RunCore()
   at System.Data.Entity.Migrations.Design.ToolingFacade.BaseRunner.Run()
Input string was not in a correct format.

I've implemented the Generate(InsertHistoryOperation insertHistoryOperation) method to add the migrations history like this:

protectedoverridevoid Generate(InsertHistoryOperation insertHistoryOperation)
    {

        using (var writer = Writer())
        {

            writer.Write("INSERT INTO \"dbo\".\"__MigrationHistory\" (\"MigrationId\", \"Model\", \"ProductVersion\") VALUES ('");

            writer.Write(insertHistoryOperation.MigrationId + "old");

            writer.Write("',E'");

            writer.Write("x0"+ insertHistoryOperation.Model.ToHexString());

            writer.Write("','");

            writer.Write(insertHistoryOperation.ProductVersion);

            writer.Write("')");

            Statement(writer);

        }

    }

The database seems to be created perfectly, but the error is still taking me to pulling my hair. Am I saving the Model in a wrong way?

The error should be raised in this routine on the EdmModelDiffer.cs of EF trying converting the MaxLength to int.

privatestatic ColumnModel BuildColumnModel(
        XElement property, string entitySetName, ModelMetadata modelMetadata)
    {
        Contract.Requires(property != null);
        Contract.Requires(!string.IsNullOrWhiteSpace(entitySetName));
        Contract.Requires(modelMetadata != null);

        var nameAttribute = property.NameAttribute();
        var nullableAttribute = property.NullableAttribute();
        var maxLengthAttribute = property.MaxLengthAttribute();
        var precisionAttribute = property.PrecisionAttribute();
        var scaleAttribute = property.ScaleAttribute();
        var storeGeneratedPatternAttribute = property.StoreGeneratedPatternAttribute();
        var storeType = property.TypeAttribute();

        var entityType
            = modelMetadata.StoreItemCollection
                .OfType<EntityType>()
                .Single(et => et.Name.EqualsIgnoreCase(entitySetName));

        var edmProperty
            = entityType.Properties[nameAttribute];

        var typeUsage = modelMetadata.ProviderManifest.GetEdmType(edmProperty.TypeUsage);

        var defaultStoreTypeName = modelMetadata.ProviderManifest.GetStoreType(typeUsage).EdmType.Name;

        var column
            = new ColumnModel(((PrimitiveType)edmProperty.TypeUsage.EdmType).PrimitiveTypeKind, typeUsage)
                  {
                      Name = nameAttribute,
                      IsNullable
                          = !string.IsNullOrWhiteSpace(nullableAttribute)
                            && !Convert.ToBoolean(nullableAttribute, CultureInfo.InvariantCulture)
                                ? false
                                : (bool?)null,
                      MaxLength
                          = !string.IsNullOrWhiteSpace(maxLengthAttribute)
                                ? Convert.ToInt32(maxLengthAttribute, CultureInfo.InvariantCulture)
                                : (int?)null,
                      Precision
                          = !string.IsNullOrWhiteSpace(precisionAttribute)
                                ? Convert.ToByte(precisionAttribute, CultureInfo.InvariantCulture)
                                : (byte?)null,
                      Scale
                          = !string.IsNullOrWhiteSpace(scaleAttribute)
                                ? Convert.ToByte(scaleAttribute, CultureInfo.InvariantCulture)
                                : (byte?)null,
                      StoreType
                          = !storeType.EqualsIgnoreCase(defaultStoreTypeName)
                                ? storeType
                                : null
                  };

        column.IsIdentity
            = !string.IsNullOrWhiteSpace(storeGeneratedPatternAttribute)
              && storeGeneratedPatternAttribute.EqualsIgnoreCase("Identity")
              && _validIdentityTypes.Contains(column.Type);

        Facet facet;
        if (typeUsage.Facets.TryGetValue(DbProviderManifest.FixedLengthFacetName, true, out facet)
            && facet.Value != null&& (bool)facet.Value)
        {
            column.IsFixedLength = true;
        }

        if (typeUsage.Facets.TryGetValue(DbProviderManifest.UnicodeFacetName, true, out facet)
            && facet.Value != null&& !(bool)facet.Value)
        {
            column.IsUnicode = false;
        }

        var isComputed
            = !string.IsNullOrWhiteSpace(storeGeneratedPatternAttribute)
              && storeGeneratedPatternAttribute.EqualsIgnoreCase("Computed");

        if ((column.Type == PrimitiveTypeKind.Binary)
            && (typeUsage.Facets.TryGetValue(DbProviderManifest.MaxLengthFacetName, true, out facet)
                && (facet.Value isint)
                && ((int)facet.Value == 8))
            && isComputed)
        {
            column.IsTimestamp = true;
        }

        return column;
    }