Loops.yml

# Loop steps allow to execute multiple times in a row (a sequence of) other steps.
# Nested loops are supported.
# NB: step execution events are triggered only for the outermost loop step

-
    type: loop
    repeat: int # number of times to repeat execution of the sequence of sub-steps
    steps: # the migration steps that you want to be executed repeatedly
        -
            type: ...
            mode: ...
            etc: ... # New references that can be resolved anywhere inside the nested step definitions are `loop:iteration`
                     # and `loop:depth`.
                     # loop:iteration is the counter of the current loop iteration, starting at 1
                     # loop:depth is used to tell apart nested loops. I starts at depth 1
                     # f.e. you could use the following to create contents with different names: "Article [loop:depth].[loop:iteration]"
        -
            type: ...
            mode: ...
            etc: ...

    if: # Optional. If set, the loop will be skipped unless the condition is matched
        "reference:_ref_name": # name of a reference to be used for the test
            _operator_: value # allowed operators: eq, gt, gte, lt, lte, ne, count, length, regexp, satisfies


# it is possible to loop over arrays values as well. This works like a php `foreach`

-
    type: loop
    over: "reference:some_array_reference" # an array (in the php sense, in yml we might call it either a list or an associative array)
    steps: # the migration steps that you want to be executed repeatedly
        -
            type: ...
            mode: ...
            etc: ... # New references that can be resolved anywhere inside the nested step definitions are `loop:iteration`
              # , `loop:depth`, `loop:key` and `loop:value`.
              # loop:iteration is the counter of the current loop iteration, starting at 1
              # loop:depth is used to tell apart nested loops. I starts at depth 1
              # loop:key is the key of the current array element
              # loop:value is the value of the current array element
        -
            type: ...
            mode: ...
            etc: ...

    if: # Optional. If set, the loop will be skipped unless the condition is matched
        "reference:_ref_name": # name of a reference to be used for the test
            _operator_: value # allowed operators: eq, gt, gte, lt, lte, ne, count, length, regexp, satisfies

# Example: how to create a reference that holds a composite index of the current step in nested loops:

-
    type: loop
    repeat: 2
    steps:
        -
            type: reference
            mode: set
            identifier: loopindex1
            value: "[loop:iteration]"
            overwrite: true
        -
            type: loop
            repeat: 2
            steps:
                -
                    type: reference
                    mode: set
                    identifier: loopindex2
                    value: "[reference:loopindex1].[loop:iteration]"
                    overwrite: true
                -
                    type: reference
                    mode: dump
                    identifier: reference:loopindex2