/// <summary>
/// Replaces the provider of the expression with the given one.
/// </summary>
/// <typeparam name="TEntity">The type of the entity.</typeparam>
/// <param name="query">The query.</param>
/// <param name="set">The set.</param>
/// <param name="provider">The provider of the set.</param>
/// <returns></returns>
/// <exception cref="ArgumentNullException">
/// query
/// or
/// set
/// or
/// provider
/// </exception>
/// <exception cref="ArgumentException">The supplied query does not originate from a QueryRootExpression and therefor does not come from Entity Framework. - query</exception>
public static Expression ReplaceProvider <TEntity>(Expression query, DbSet <TEntity> set, IQueryProvider provider)
where TEntity : class
{
if (query is null)
{
throw new ArgumentNullException(nameof(query));
}
if (set is null)
{
throw new ArgumentNullException(nameof(set));
}
if (provider is null)
{
throw new ArgumentNullException(nameof(provider));
}
var setQuery = provider is IAsyncQueryProvider asyncProvider ?
new QueryRootExpression(asyncProvider, set.EntityType) :
new QueryRootExpression(set.EntityType);
var visitor = new QueryRootExpressionReplaceVisitor(setQuery);
var replaced = visitor.Visit(query);
if (!visitor.queryWasReplaced)
{
throw new ArgumentException($"The supplied query does not originate from a {nameof(QueryRootExpression)} and therefor does not come from Entity Framework.", nameof(query));
}
return(replaced ?? throw new ArgumentException($"The supplied query resulted in a replaces expression which was null. This should not happen.", nameof(query)));
}
private static Expression ReplaceProvider(Expression query, DbSet <TEntity> set, IQueryProvider provider) => QueryRootExpressionReplaceVisitor.ReplaceProvider(query, set, provider);