protected override void OnSave(string value)
{
base.OnSave(value);
Model.Parameter = JsonHelper.Serialize(ParameterValues.ToDictionary(x => x.Name, x => x.Value));
}
/// <summary>
/// Converts the SQL into an UPDATE statement.
/// </summary>
/// <param name="update">The field or fields to update.</param>
/// <returns></returns>
public ParameterizedSql <TEntity> ToUpdate(Expression <Func <TEntity, TEntity> > update)
{
if (ReadOnly)
{
throw new InvalidOperationException("The UPDATE SQL cannot be automatically generated from this statement.");
}
if (!IsSelect)
{
throw new InvalidOperationException("Only SELECT statements can be converted to UPDATE statements.");
}
if (IsGrouped)
{
throw new InvalidOperationException("An aggregate SELECT statement cannot be converted to an UPDATE statement.");
}
if (HasWithExpression)
{
throw new InvalidOperationException("A SELECT statement with a WITH clause cannot be converted to an UPDATE statement.");
}
if (!(update.Body is MemberInitExpression initExpression))
{
throw new InvalidOperationException("The update expression must be a member initialization expression.");
}
var paramValues = ParameterValues.ToDictionary(x => x.Key, x => x.Value);
var builder = new StringBuilder();
_logger?.LogDebug("Generating UPDATE SQL");
var context = DbContext ??
throw new InvalidOperationException("No current DbContext available.");
var entityType = context.Model.FindEntityType(typeof(TEntity)) ??
throw new InvalidOperationException("Failed to locate entity type.");
builder.Append("UPDATE ");
string subAlias;
if (_knowledge.UpdateSupportsTableAliases)
{
if (_knowledge.UpdateSupportsFromClause)
{
// UPDATE supports aliases and a FROM clause.
builder.Append(_knowledge.QuoteObjectName(_tableAlias)).Append(" SET ");
}
else
{
// UPDATE supports aliases, but not the from clause (MySQL, MariaDB)
// The tables and aliases are specified immediately following the UPDATE keyword, so we can
// trim off the FROM keyword and just append the rest of the from clause.
builder.Append(_fromClause.Substring(5)).Append(" SET ");
}
subAlias = _knowledge.QuoteObjectName(_tableAlias) + ".";
}
else
{
builder.Append(_tableName).Append(" SET ");
subAlias = "";
}
bool first = true;
foreach (var binding in initExpression.Bindings)
{
if (!(binding is MemberAssignment assignment))
{
throw new InvalidOperationException("Only simple assignment bindings are supported in the update expression.");
}
if (!first)
{
builder.Append(", ");
}
first = false;
var prop = entityType.FindProperty(assignment.Member.Name) ??
throw new InvalidOperationException(
$"The entity does not contain a {assignment.Member.Name} property."
);
builder.Append(subAlias);
builder.Append(ColumnNameFor(prop)).Append(" = ");
AddColumnValue(assignment.Expression, builder, paramValues, context, entityType);
}
if (_knowledge.UpdateSupportsTableAliases)
{
if (_knowledge.UpdateSupportsFromClause)
{
builder.Append(' ').Append(_fromClause);
}
builder.Append(' ').Append(_whereClause);
}
else
{
builder.Append(' ').Append(GenerateUnAliasedWhereClause());
}
var sql = builder.ToString().Trim();
_logger?.LogDebug(sql);
return(new ParameterizedSql <TEntity>(
this,
"UPDATE",
sql,
paramValues
));
}
