javajdbistringtemplate-4

jdbi version 3, stringtemplate when to escape <, > characters?

I am using jdbi3 with StringTemplate 4 templating engine, I have this test query:

    @SqlQuery("select * from test "
        + "where field1 = 5"
        + "<if(cond1)> or field2 \\<= :value1<endif>"
        + "<if(cond2)> or field2 >= :value2<endif>"
        + "<if(cond3)> or field2 in (<values>)<endif>")
@RegisterBeanMapper(Test.class)
@UseStringTemplateEngine
public List<Test> selectTest(
        @Define("cond1") boolean cond1, @Bind("value1") int value2,
        @Define("cond2") boolean cond2, @Bind("value2") int value3,
        @Define("cond3") boolean cond3,
        @BindList(value="values", onEmpty=BindList.EmptyHandling.NULL_STRING ) List<Integer> values);

Using StringTemplate engine when I have to escape with \ the characters < or > in the query? Testing I found that I have to escape <= in the query like I did.

In the IN clause using @BindList I have to use the <values> but in this case I was expecting to escape it like \\<values> otherwise it will be used as attribute by StringTemplate but if I do this the query doesn't work.

About >= escaping it or not seems the same in the query.

Solution

  • Introduction

    Let's consider:

    Answer

    Jdbi

    Documentation: Which characters to escape

    Please, note the warning on which characters to escape:

    Since StringTemplate by default uses the < character to mark ST expressions, you might need to escape some SQL: String datePredSql = "<if(datePredicate)> <dateColumn> \\< :dateFilter <endif>"

    — jdbi/index.adoc at v3.27.1 · jdbi/jdbi.

    Unit-test: Do not escape @BindList variable name

    Please, see the BindListTest.ifValueGivenWithNullValueOptionThenResultIsTruthy() test method: jdbi/BindListTest.java at v3.27.1 · jdbi/jdbi.

    Please, note that the test covers a very similar annotated method:

    @SqlQuery("select name from something <if(name)> where name in (<name>) <endif>")
@UseStringTemplateEngine
List<String> getForValue(@Nonnull @BindList(value = "name", onEmpty = NULL_VALUE) List<String> name);

    Please, note that the @BindList variable name is not escaped:

    in (<name>)

    StringTemplate

    Documentation: Which characters to escape

    Please, note which characters to escape:

    A template is a sequence of text and expression elements, optionally interspersed with comments. At the coarsest level, the basic elements are:

    text
<expr>
<! comment !>

    Escape delimiters with a backslash character: \< or \>.

    — stringtemplate4/templates.md at 4.3.1 · antlr/stringtemplate4.