Handling escape sequence in query params in rails app server with Postgres












0















query_string = params[:q]
model.where("name ILIKE ? ", "#{query_string}").limit(10)


In the controller I have the above lines



params[:q] is the user input.



Whenever the user input ends with , say police , Postgres throws this error:



ActionView::Template::Error (PG::InvalidEscapeSequence: ERROR:  LIKE pattern must not end with escape character.


How can we gracefully handle such cases?










share|improve this question





























    0















    query_string = params[:q]
    model.where("name ILIKE ? ", "#{query_string}").limit(10)


    In the controller I have the above lines



    params[:q] is the user input.



    Whenever the user input ends with , say police , Postgres throws this error:



    ActionView::Template::Error (PG::InvalidEscapeSequence: ERROR:  LIKE pattern must not end with escape character.


    How can we gracefully handle such cases?










    share|improve this question



























      0












      0








      0








      query_string = params[:q]
      model.where("name ILIKE ? ", "#{query_string}").limit(10)


      In the controller I have the above lines



      params[:q] is the user input.



      Whenever the user input ends with , say police , Postgres throws this error:



      ActionView::Template::Error (PG::InvalidEscapeSequence: ERROR:  LIKE pattern must not end with escape character.


      How can we gracefully handle such cases?










      share|improve this question
















      query_string = params[:q]
      model.where("name ILIKE ? ", "#{query_string}").limit(10)


      In the controller I have the above lines



      params[:q] is the user input.



      Whenever the user input ends with , say police , Postgres throws this error:



      ActionView::Template::Error (PG::InvalidEscapeSequence: ERROR:  LIKE pattern must not end with escape character.


      How can we gracefully handle such cases?







      ruby-on-rails postgresql sql-like






      share|improve this question















      share|improve this question













      share|improve this question




      share|improve this question








      edited Nov 13 '18 at 7:04







      Surya

















      asked Nov 13 '18 at 6:44









      SuryaSurya

      327111




      327111
























          1 Answer
          1






          active

          oldest

          votes


















          1














          Use a different escape character, for example:



          WHERE name ILIKE 'pattern' ESCAPE '/'


          If you have no safe escape character, you can double it:



          WHERE nane ILIKE replace('pattern', '', '\')





          share|improve this answer


























          • Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

            – Surya
            Nov 13 '18 at 6:59











          • how can gracefully handle all such cases?

            – Surya
            Nov 13 '18 at 7:01











          • Double the escape character as indicated in the extended answer.

            – Laurenz Albe
            Nov 13 '18 at 7:07











          • if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

            – Surya
            Nov 13 '18 at 7:14






          • 1





            Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

            – Laurenz Albe
            Nov 13 '18 at 7:17













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          1 Answer
          1






          active

          oldest

          votes








          1 Answer
          1






          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes









          1














          Use a different escape character, for example:



          WHERE name ILIKE 'pattern' ESCAPE '/'


          If you have no safe escape character, you can double it:



          WHERE nane ILIKE replace('pattern', '', '\')





          share|improve this answer


























          • Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

            – Surya
            Nov 13 '18 at 6:59











          • how can gracefully handle all such cases?

            – Surya
            Nov 13 '18 at 7:01











          • Double the escape character as indicated in the extended answer.

            – Laurenz Albe
            Nov 13 '18 at 7:07











          • if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

            – Surya
            Nov 13 '18 at 7:14






          • 1





            Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

            – Laurenz Albe
            Nov 13 '18 at 7:17


















          1














          Use a different escape character, for example:



          WHERE name ILIKE 'pattern' ESCAPE '/'


          If you have no safe escape character, you can double it:



          WHERE nane ILIKE replace('pattern', '', '\')





          share|improve this answer


























          • Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

            – Surya
            Nov 13 '18 at 6:59











          • how can gracefully handle all such cases?

            – Surya
            Nov 13 '18 at 7:01











          • Double the escape character as indicated in the extended answer.

            – Laurenz Albe
            Nov 13 '18 at 7:07











          • if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

            – Surya
            Nov 13 '18 at 7:14






          • 1





            Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

            – Laurenz Albe
            Nov 13 '18 at 7:17
















          1












          1








          1







          Use a different escape character, for example:



          WHERE name ILIKE 'pattern' ESCAPE '/'


          If you have no safe escape character, you can double it:



          WHERE nane ILIKE replace('pattern', '', '\')





          share|improve this answer















          Use a different escape character, for example:



          WHERE name ILIKE 'pattern' ESCAPE '/'


          If you have no safe escape character, you can double it:



          WHERE nane ILIKE replace('pattern', '', '\')






          share|improve this answer














          share|improve this answer



          share|improve this answer








          edited Nov 13 '18 at 7:06

























          answered Nov 13 '18 at 6:55









          Laurenz AlbeLaurenz Albe

          45k102747




          45k102747













          • Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

            – Surya
            Nov 13 '18 at 6:59











          • how can gracefully handle all such cases?

            – Surya
            Nov 13 '18 at 7:01











          • Double the escape character as indicated in the extended answer.

            – Laurenz Albe
            Nov 13 '18 at 7:07











          • if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

            – Surya
            Nov 13 '18 at 7:14






          • 1





            Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

            – Laurenz Albe
            Nov 13 '18 at 7:17





















          • Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

            – Surya
            Nov 13 '18 at 6:59











          • how can gracefully handle all such cases?

            – Surya
            Nov 13 '18 at 7:01











          • Double the escape character as indicated in the extended answer.

            – Laurenz Albe
            Nov 13 '18 at 7:07











          • if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

            – Surya
            Nov 13 '18 at 7:14






          • 1





            Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

            – Laurenz Albe
            Nov 13 '18 at 7:17



















          Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

          – Surya
          Nov 13 '18 at 6:59





          Nope then if the user enters 'Police /' I will be getting the same error right? params[:q] is a user input.

          – Surya
          Nov 13 '18 at 6:59













          how can gracefully handle all such cases?

          – Surya
          Nov 13 '18 at 7:01





          how can gracefully handle all such cases?

          – Surya
          Nov 13 '18 at 7:01













          Double the escape character as indicated in the extended answer.

          – Laurenz Albe
          Nov 13 '18 at 7:07





          Double the escape character as indicated in the extended answer.

          – Laurenz Albe
          Nov 13 '18 at 7:07













          if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

          – Surya
          Nov 13 '18 at 7:14





          if I use replace then in valid cases like 'police a ' it will get queried as 'police \a' isn't it? Isn't that not desirable?? But chances that I get input like 'police a ' is minimal so I might as well use this, but still wondering..

          – Surya
          Nov 13 '18 at 7:14




          1




          1





          Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

          – Laurenz Albe
          Nov 13 '18 at 7:17







          Well, if the backslash sometimes is an escape character and sometimes not, you need to have additional information. There is no way to guess which is meant.

          – Laurenz Albe
          Nov 13 '18 at 7:17




















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