public SqlExpression TranslateArrayLength(SqlExpression expression)
{
if (expression is ColumnExpression columnExpression &&
columnExpression.TypeMapping is NpgsqlJsonTypeMapping mapping)
{
return(_sqlExpressionFactory.Function(
mapping.IsJsonb ? "jsonb_array_length" : "json_array_length",
new[] { expression }, typeof(int)));
}
if (expression is JsonTraversalExpression traversal)
{
// The traversal expression has ReturnsText=true (e.g. ->> not ->), so we recreate it to return
// the JSON object instead.
var lastPathComponent = traversal.Path.Last();
var newTraversal = new JsonTraversalExpression(
traversal.Expression, traversal.Path,
returnsText: false,
lastPathComponent.Type,
_sqlExpressionFactory.FindMapping(lastPathComponent.Type));
var jsonMapping = (NpgsqlJsonTypeMapping)traversal.Expression.TypeMapping;
return(_sqlExpressionFactory.Function(
jsonMapping.IsJsonb ? "jsonb_array_length" : "json_array_length",
new[] { newTraversal }, typeof(int)));
}
return(null);
}
public SqlExpression Translate(SqlExpression instance, MethodInfo method, IReadOnlyList <SqlExpression> arguments)
{
if (method.DeclaringType != typeof(JsonElement) ||
!(instance.TypeMapping is NpgsqlJsonTypeMapping mapping))
{
return(null);
}
if (method == GetProperty || method == ArrayIndexer)
{
// The first time we see a JSON traversal it's on a column - create a JsonTraversalExpression.
// Traversals on top of that get appended into the same expression.
return(instance is ColumnExpression columnExpression
? _sqlExpressionFactory.JsonTraversal(columnExpression, arguments, false, typeof(string), mapping)
: instance is JsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(_sqlExpressionFactory.ApplyDefaultTypeMapping(arguments[0]))
: null);
}
if (GetMethods.Contains(method.Name) &&
arguments.Count == 0 &&
instance is JsonTraversalExpression traversal)
{
var traversalToText = new JsonTraversalExpression(
traversal.Expression,
traversal.Path,
returnsText: true,
typeof(string),
_stringTypeMapping);
return(method.Name == nameof(JsonElement.GetString)
? traversalToText
: ConvertFromText(traversalToText, method.ReturnType));
}
if (method == GetArrayLength)
{
return(_sqlExpressionFactory.Function(
mapping.IsJsonb ? "jsonb_array_length" : "json_array_length",
new[] { instance }, typeof(int)));
}
if (method.Name.StartsWith("TryGet") && arguments.Count == 0)
{
throw new InvalidOperationException($"The TryGet* methods on {nameof(JsonElement)} aren't translated yet, use Get* instead.'");
}
return(null);
}
