public virtual 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 },
nullable: true,
argumentsPropagateNullability: TrueArrays[2],
typeof(int)));
}
if (expression is PostgresJsonTraversalExpression 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 PostgresJsonTraversalExpression(
traversal.Expression, traversal.Path,
returnsText: false,
lastPathComponent.Type,
_typeMappingSource.FindMapping(lastPathComponent.Type));
var jsonMapping = (NpgsqlJsonTypeMapping)traversal.Expression.TypeMapping !;
return(_sqlExpressionFactory.Function(
jsonMapping.IsJsonb ? "jsonb_array_length" : "json_array_length",
new[] { newTraversal },
nullable: true,
argumentsPropagateNullability: TrueArrays[2],
typeof(int)));
}
return(null);
}
public virtual SqlExpression?Translate(
SqlExpression?instance,
MethodInfo method,
IReadOnlyList <SqlExpression> arguments,
IDiagnosticsLogger <DbLoggerCategory.Query> logger)
{
if (method.DeclaringType != typeof(JsonElement) ||
instance?.TypeMapping is not NpgsqlJsonTypeMapping mapping)
{
return(null);
}
// The root of the JSON expression is a ColumnExpression. We wrap that with an empty traversal
// expression (col #>> '{}'); subsequent traversals will gradually append the path into that.
// Note that it's possible to call methods such as GetString() directly on the root, and the
// empty traversal is necessary to properly convert it to a text.
instance = instance is ColumnExpression columnExpression
? _sqlExpressionFactory.JsonTraversal(
columnExpression, returnsText : false, typeof(string), mapping)
: instance;
if (method == GetProperty || method == ArrayIndexer)
{
return(instance is PostgresJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(_sqlExpressionFactory.ApplyDefaultTypeMapping(arguments[0]))
: null);
}
if (GetMethods.Contains(method.Name) &&
arguments.Count == 0 &&
instance is PostgresJsonTraversalExpression traversal)
{
var traversalToText = new PostgresJsonTraversalExpression(
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 },
nullable: true,
argumentsPropagateNullability: TrueArrays[1],
typeof(int)));
}
if (method.Name.StartsWith("TryGet", StringComparison.Ordinal) && arguments.Count == 0)
{
throw new InvalidOperationException($"The TryGet* methods on {nameof(JsonElement)} aren't translated yet, use Get* instead.'");
}
return(null);
}
public SqlExpression?Translate(SqlExpression instance, MethodInfo method, IReadOnlyList <SqlExpression> arguments, IDiagnosticsLogger <DbLoggerCategory.Query> logger)
{
if (typeof(JToken).IsAssignableFrom(method.DeclaringType) &&
method.Name == "get_Item" &&
arguments.Count == 1)
{
return((instance is ColumnExpression columnExpression
? _sqlExpressionFactory.JsonTraversal(
columnExpression, returnsText: false, typeof(string), instance.TypeMapping)
: instance) is PostgresJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(_sqlExpressionFactory.ApplyDefaultTypeMapping(arguments[0]))
: null);
}
if (arguments.FirstOrDefault() is PostgresJsonTraversalExpression traversal)
{
// Support for .Value<T>() and .Value<U, T>():
if (instance == null &&
method.Name == nameof(Extensions.Value) &&
method.DeclaringType == typeof(Extensions) &&
method.IsGenericMethod &&
method.GetParameters().Length == 1 &&
arguments.Count == 1)
{
var traversalToText = new PostgresJsonTraversalExpression(
traversal.Expression,
traversal.Path,
returnsText: true,
typeof(string),
_stringTypeMapping);
if (method.ReturnType == typeof(string))
{
return(traversalToText);
}
else
{
return(_sqlExpressionFactory.Convert(traversalToText, method.ReturnType, _typeMappingSource.FindMapping(method.ReturnType)));
}
}
// Support for Count()
if (instance == null &&
method.Name == nameof(Enumerable.Count) &&
method.DeclaringType == typeof(Enumerable) &&
method.IsGenericMethod &&
method.GetParameters().Length == 1 &&
arguments.Count == 1)
{
return(_jsonPocoTranslator.TranslateArrayLength(traversal));
}
// Predicate-less Any - translate to a simple length check.
if (method.IsClosedFormOf(_enumerableAnyWithoutPredicate) &&
arguments.Count == 1 &&
arguments[0].Type.TryGetElementType(out _) &&
arguments[0].TypeMapping is NpgsqlJsonTypeMapping)
{
return(_sqlExpressionFactory.GreaterThan(
_jsonPocoTranslator.TranslateArrayLength(arguments[0]),
_sqlExpressionFactory.Constant(0)));
}
}
return(null);
}
