public virtual SqlExpression TranslateMemberAccess(
[NotNull] SqlExpression instance, [NotNull] SqlExpression member, [NotNull] Type returnType)
{
// 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.
if (instance is ColumnExpression columnExpression &&
columnExpression.TypeMapping is MySqlJsonTypeMapping)
{
return(ConvertFromJsonExtract(
_sqlExpressionFactory.JsonTraversal(
columnExpression,
returnsText: returnType == typeof(string),
returnType)
.Append(
member,
returnType,
FindPocoTypeMapping(returnType)),
returnType));
}
if (instance is MySqlJsonTraversalExpression prevPathTraversal)
{
return(prevPathTraversal.Append(
member,
returnType,
FindPocoTypeMapping(returnType)));
}
return(null);
}
public virtual SqlExpression Translate(SqlExpression instance, MethodInfo method, IReadOnlyList <SqlExpression> arguments)
{
if (method.DeclaringType != typeof(JsonElement) ||
!(instance.TypeMapping is MySqlJsonTypeMapping mapping))
{
return(null);
}
// The root of the JSON expression is a ColumnExpression. We wrap that with an empty traversal
// expression (col->'$'); subsequent traversals will gradually append the path into that.
// Note that it's possible to call methods such as GetString() directly on the root, and the
// empty traversal is necessary to properly convert it to a text.
instance = instance is ColumnExpression columnExpression
? _sqlExpressionFactory.JsonTraversal(
columnExpression, returnsText : false, typeof(string), mapping)
: instance;
if (method == _getProperty)
{
return(instance is MySqlJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(
ApplyPathLocationTypeMapping(arguments[0]),
typeof(JsonElement),
_typeMappingSource.FindMapping(typeof(JsonElement)))
: null);
}
if (method == _arrayIndexer)
{
return(instance is MySqlJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(
_sqlExpressionFactory.JsonArrayIndex(ApplyPathLocationTypeMapping(arguments[0])),
typeof(JsonElement),
_typeMappingSource.FindMapping(typeof(JsonElement)))
: null);
}
if (_getMethods.Contains(method.Name) &&
arguments.Count == 0 &&
instance is MySqlJsonTraversalExpression traversal)
{
return(ConvertFromJsonExtract(
traversal.Clone(
method.Name == nameof(JsonElement.GetString),
method.ReturnType,
_typeMappingSource.FindMapping(method.ReturnType)
),
method.ReturnType));
}
if (method == _getArrayLength)
{
return(_sqlExpressionFactory.Function(
"JSON_LENGTH",
new[] { instance },
typeof(int)));
}
if (method.Name.StartsWith("TryGet") && arguments.Count == 0)
{
throw new InvalidOperationException($"The TryGet* methods on {nameof(JsonElement)} aren't translated yet, use Get* instead.'");
}
return(null);
}
public SqlExpression Translate(SqlExpression instance, MethodInfo method, IReadOnlyList <SqlExpression> arguments, IDiagnosticsLogger <DbLoggerCategory.Query> logger)
{
if (instance != null && instance.Type.IsGenericList() && method.Name == "get_Item" && arguments.Count == 1)
{
// Try translating indexing inside json column
return(_jsonPocoTranslator.TranslateMemberAccess(instance, arguments[0], method.ReturnType));
}
// 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 MySqlJsonTypeMapping)
{
return(_sqlExpressionFactory.GreaterThan(
_jsonPocoTranslator.TranslateArrayLength(arguments[0]),
_sqlExpressionFactory.Constant(0)));
}
if (method.DeclaringType != typeof(JsonElement) ||
!(instance.TypeMapping is MySqlJsonTypeMapping mapping))
{
return(null);
}
// The root of the JSON expression is a ColumnExpression. We wrap that with an empty traversal
// expression (col->'$'); subsequent traversals will gradually append the path into that.
// Note that it's possible to call methods such as GetString() directly on the root, and the
// empty traversal is necessary to properly convert it to a text.
instance = instance is ColumnExpression columnExpression
? _sqlExpressionFactory.JsonTraversal(
columnExpression, returnsText : false, typeof(string), mapping)
: instance;
if (method == _getProperty)
{
return(instance is MySqlJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(
ApplyPathLocationTypeMapping(arguments[0]),
typeof(JsonElement),
_typeMappingSource.FindMapping(typeof(JsonElement)))
: null);
}
if (method == _arrayIndexer)
{
return(instance is MySqlJsonTraversalExpression prevPathTraversal
? prevPathTraversal.Append(
_sqlExpressionFactory.JsonArrayIndex(ApplyPathLocationTypeMapping(arguments[0])),
typeof(JsonElement),
_typeMappingSource.FindMapping(typeof(JsonElement)))
: null);
}
if (_getMethods.Contains(method.Name) &&
arguments.Count == 0 &&
instance is MySqlJsonTraversalExpression traversal)
{
return(ConvertFromJsonExtract(
traversal.Clone(
method.Name == nameof(JsonElement.GetString),
method.ReturnType,
_typeMappingSource.FindMapping(method.ReturnType)
),
method.ReturnType));
}
if (method == _getArrayLength)
{
// Could return NULL if the path is not found, but we would be alright to throw then.
return(_sqlExpressionFactory.NullableFunction(
"JSON_LENGTH",
new[] { instance },
typeof(int),
false));
}
if (method.Name.StartsWith("TryGet") && arguments.Count == 0)
{
throw new InvalidOperationException($"The TryGet* methods on {nameof(JsonElement)} aren't translated yet, use Get* instead.'");
}
return(null);
}