SQL Server

JSON Escape and Unescape a String

Demonstrates how to JSON escape or unescape a string. SQL Server

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    -- Important: Do not use nvarchar(max).  See the warning about using nvarchar(max).
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @sb int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sb OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @success int
    EXEC sp_OAMethod @sb, 'Append', @success OUT, 'backslash: \\, A: \u0041'
    EXEC sp_OAMethod @sb, 'GetAsString', @sTmp0 OUT
    PRINT @sTmp0

    -- The output is:
    --    backslash: \\, A: \u0041

    -- The keyword "json" can be used
    -- to escape and unescape.  To escape is to encode.  To unescape is to decode.

    -- Unescape (decode) the string in sb.
    EXEC sp_OAMethod @sb, 'Decode', @success OUT, 'json', 'utf-8'
    EXEC sp_OAMethod @sb, 'GetAsString', @sTmp0 OUT
    PRINT @sTmp0

    -- After JSON unescaping:
    --    backslash: \, A: A

    -- Now JSON escape the string.
    EXEC sp_OAMethod @sb, 'Encode', @success OUT, 'json', 'utf-8'
    EXEC sp_OAMethod @sb, 'GetAsString', @sTmp0 OUT
    PRINT @sTmp0

    -- After JSON escaping:
    --    backslash: \\, A: A

    -- Note: The "A" is not escaped to "\u0041" because there is no need.
    -- The "\uXXXX" format would be produced for non-printable control chars.

    EXEC @hr = sp_OADestroy @sb


END
GO