ExecuteXmlReader Fails on Specific JSON from SQL Server - .net-core

Question

I have an existing working process which receives generated JSON from store procedures in SQL Server using the for JSON directive. But upon receiving a specific text in the column data, there is a failure by ExecuteXmlReader in the Read operation.
Exception
XmlException: '=' is an unexpected token. The expected token is ';'.
Line 1, position 94
Which if I controlled the output, I would most likely put it in a CDATA section.
Data Returned from SQL Server
JSON_F52E2B61-18A1-11d1-B105-00805F49916B
{"photoId":1000000007,"photoType":"image\/gif","photoUrl":"https:\/\/slack-imgs.com\/?c=1&url=https%3A%2F%2Fmedia0.giphy.com%2Fmedia%2F3o84U9arAYRM73AIvu%2Fgiphy-downsized.gif" }
Ultimate JSON String Which Should be Returned by Read
{
"photoId": 1000000007,
"photoType": "image/gif",
"photoUrl": "https://slack-imgs.com/?c=1&url=https%3A%2F%2Fmedia0.giphy.com%2Fmedia%2F3o84U9arAYRM73AIvu%2Fgiphy-downsized.gif",
"isActive": true
}
URL saved to Table
https://slack-imgs.com/?c=1&url=https%3A%2F%2Fmedia0.giphy.com%2Fmedia%2F3o84U9arAYRM73AIvu%2Fgiphy-downsized.gif
Ultimately this is a SQL Server 2016 change but I will need a fix sooner than what can be provided from Microsoft. So, is there a work around to handle this either by SQL or C# .Net code?
Oddly enough when one clicks on the table column value JSON in SSMS, it gives the same error.

Answer 1

I'll go ahead and propose that you are using the wrong APIs to read the FOR JSON query results. Here's a little helper class that implements a SqlCommand.ExecuteJsonReader() extension method.
static class SqlJsonUtils
{
public static Newtonsoft.Json.JsonReader ExecuteJsonReader(this SqlCommand cmd)
{
var rdr = cmd.ExecuteReader();
var jr = new Newtonsoft.Json.JsonTextReader(new SqlJSONReader(rdr));
return jr;
}
class SqlJSONReader : System.IO.TextReader
{
SqlDataReader rdr;
string currentLine = "";
int currentPos = 0;
public SqlJSONReader(SqlDataReader rdr)
{
this.rdr = rdr;
}
public override int Peek()
{
return GetChar(false);
}
public override int Read()
{
return GetChar(true);
}
public int GetChar(bool Advance)
{
while (currentLine.Length == currentPos)
{
if (!rdr.Read())
{
return -1;
}
currentLine = rdr.GetString(0);
currentPos = 0;
}
int rv = (int)currentLine[currentPos];
if (Advance) currentPos += 1;
return rv;
}
public override void Close()
{
rdr.Close();
}
}
}

Answer 2

I have since made this a downloadable NUGET package. See SQLJSONReader with updates for async.
I took David's advice and marked his as the answer, but I needed the whole raw JSON.
So I added removed the call to to Newtonsoft.Json.JsonTextReader because it wouldn't return me just a string and modified David's extension class to return the whole JSON by calling ReadAll.
Note that it uses Newtonsoft's JsonConvert.DeserializeObject.
Code
public static SqlJSONReader ExecuteJsonReader(this SqlCommand cmd)
{
var rdr = cmd.ExecuteReader();
return new SqlJSONReader(rdr);
}
public class SqlJSONReader : System.IO.TextReader
{
private SqlDataReader SqlReader { get; set; }
private string CurrentLine { get; set; }
private int CurrentPostion { get; set; }
public SqlJSONReader(SqlDataReader rdr)
{
CurrentLine = "";
CurrentPostion = 0;
this.SqlReader = rdr;
}
public override int Peek()
{
return GetChar(false);
}
public override int Read()
{
return GetChar(true);
}
public int GetChar(bool Advance)
{
while (CurrentLine.Length == CurrentPostion)
{
if (!SqlReader.Read())
{
return -1;
}
CurrentLine = SqlReader.GetString(0);
CurrentPostion = 0;
}
var rv = CurrentLine[CurrentPostion];
if (Advance)
CurrentPostion += 1;
return rv;
}
public string ReadAll()
{
var sbResult = new StringBuilder();
if (SqlReader.HasRows)
{
while (SqlReader.Read())
sbResult.Append(SqlReader.GetString(0));
}
else
return string.Empty;
// Clean up any JSON escapes before returning
return JsonConvert.DeserializeObject(sbResult.ToString()).ToString();
}
public override void Close() { SqlReader.Close(); }
}
Usage
using (SqlConnection conn = new SqlConnection(connectionString))
using (SqlCommand cmd = conn.CreateCommand())
{
cmd.CommandText = "exec [dbo].[GetPhoto] #PhotoId=4";
conn.Open();
var rdr = cmd.ExecuteJsonReader();
string jsonResult = rdr.ReadAll();
conn.Close();
}