Conditional Branching

Just as if/else allows you to implement control flow in your programs, Conditional Branching allows you to add control flow to your LittleHorse Workflows.

Let's look at how an if statement works in Python:

if foo < bar:
    do_something()

Look at the booean expression foo < bar. It consists of a left-hand-side (foo), comparator (<), and right-hand-side (bar).

In LittleHorse, we have Edge Conditions, which also have an LHS, Comparator, and RHS.

The LHS and RHS are any VariableAssignment, meaning they can be a value taken from some Variable or a hard-coded literal value.

Comparator Types

Let's look at all of the Comparators supported by LittleHorse.

LESS_THAN

This is equivalent to < and is valid for STR, INT, DOUBLE, and BOOL RHS and LHS.

Note that you may provide a JSON_OBJ variable with a jsonPath as one of your comparands so long as the result of evaluating the jsonPath is a primitive type.

For example, with the following JSON_OBJ variable (let's say the variable is named myVar):

{
    "foo": "Hello, there!",
    "bar": {
        "baz": 1234
    }
}

You could do the following in the Java SDK:

// myVar.bar.baz < 500
thread.condition(myVar.jsonPath("$.bar.baz), ComparatorPb.LESS_THAN, 500)

GREATER_THAN

This is the same as LESS_THAN, except it corresponds to >.

LESS_THAN_EQ

This is the same as LESS_THAN and GREATER_THAN, except it corresponds to <=.

GREATER_THAN_EQ

Well, you know the drill... >=.

EQUALS

This is valid for any variable type, and is similar to .equals() in Java.

One note: if the RHS is a different type from the LHS, then LittleHorse will try to cast the RHS to the same type as the LHS (see the Variables section for more info). If the cast fails, then the ThreadRun fails with a VAR_SUB_ERROR.

NOT_EQUALS

This is the inverse of EQUALS.

IN

This is valid for any type on the LHS and JSON_OBJ and JSON_ARR on the RHS. For the JSON_OBJ type, this returns true if the LHS has a key which is equal to the RHS. For the JSON_ARR type, it returns true if one of the elements of the RHS is equal to the LHS.

NOT_IN

This is the inverse of IN.