[masklinn]

> This is incorrect. The producer emits something in a language, be it HTML or JSON or HTTP headers or whatever. Data must be encoded properly for that language.

Which is the consumption side. When you send data to an HTML template engine, it’s escaped as input, meaning with the template engine as consumer, not with the template engine as producer.

It may be a “pipeline” situation where the consumer also produces something (e.g. JSON or HTML), but it doesn’t have to be e.g. an SQL interface might have no production, but the data it consumes still needs to be properly escaped.

When your producer produces data, it has no idea how that data will be used, and that’s what determines the necessary transformations e.g. it’s of no help to you if your templating engine generates content escaped for MSSQL when you’re not going to put it in MSSQL.

[cesarb]

> it’s of no help to you if your templating engine generates content escaped for MSSQL when you’re not going to put it in MSSQL.

Allow me to complain a bit about MSSQL.

When you're escaping a LIKE expression for MSSQL, you must also escape the "[" character, since it's a wildcard for MSSQL (and nowhere else except AFAIK Sybase). When you're escaping a LIKE expression for other databases, you must not escape the "[" character, since some databases reject escaping anything other than the % and _ wildcards. That is, your escaping code for a LIKE expression has to be database-specific, because MSSQL (and AFAIK Sybase, it seems both have a common ancestor) decided to be different.

[masklinn]

> When you're escaping a LIKE expression for other databases, you must not escape the "[" character, since some databases reject escaping anything other than the % and _ wildcards. That is, your escaping code for a LIKE expression has to be database-specific, because MSSQL (and AFAIK Sybase, it seems both have a common ancestor) decided to be different.

TBF you may need custom codepaths because defaults diverge as well, IIRC postgres and sqlite default to ESCAPE '\' while mssql and oracle default to ESCAPE '' (the latter being the actual spec behaviour).

So in Postgres and SQLite you must always escape your LIKE parameter, while in mssql and oracle that's not the case.

[cesarb]

> TBF you may need custom codepaths because defaults diverge as well, IIRC postgres and sqlite default to ESCAPE '\' while mssql and oracle default to ESCAPE '' (the latter being the actual spec behaviour).

The trick is to just avoid the default, and always use an explicit ESCAPE, which should work the same on every database (except mysql without NO_BACKSLASH_ESCAPES in which you also have to escape the backslash itself, otherwise it will escape the closing quote and get very confused, but that issue can be avoided by using a character other than backslash as the escape character).