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    Flow Control

    Last updated: 2024-01-20 17:44:35
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      Overview

      The writing method of the flow control logic in commonly used programming languages is different from that in DSL functions. See the figure below.
      
      
      

      Function compose

      Function definition

      This function is used to combine multiple operation functions. Providing combination capabilities similar to those of branch code blocks, this function can combine multiple operation functions and execute them in sequence. It can be used in combination with branches and output functions.

      Syntax description

      compose(Function 1,Function 2, ...)

      Parameter description

      Parameter
      Description
      Parameter Type
      Required
      Default Value
      Value Range
      Variable parameter, function
      The parameter must be a function whose return value type is LOG.
      string
      At least one function parameter
      -
      -

      Example

      Example 1. Call functions in sequence, executing the enrich function first and then the fields_set function Raw log:
      {"status": "500"}
      Processing rule: 
      // 1. `enrich` function: use the data in `dict` to enrich the raw log, where `status` is `500`, and generate a field (field `message` with value `Failed`) after the enrichment.
      //2. `fields_Set` function: add a field `new` and assign value `1` to it.
      compose(enrich_dict("{\\"200\\":\\"SUCCESS\\",\\"500\\":\\"FAILED\\"}", "status", output="message"), fields_set("new", 1))
      Processing result:
      // The final log contains 3 fields:
      {"new":"1","message":"FAILED","status":"500"}
      Example 2 Raw log:
      {"status": "500"}
      Processing rule:
      compose(fields_set("new", 1))
      Processing result:
      {"new":"1","status":"500"}
      Example 3 Raw log:
      {"condition1": 0,"condition2": 1, "status": "500"}
      Processing rule:
      t_if_else(v("condition2"), compose(fields_set("new", 1),log_output("target")), log_output("target2"))
      Processing result, target output: 
      {"new":"1","condition1":"0","condition2":"1","status":"500"}

      Function t_if

      Function definition

      This function is used to execute a corresponding function if a condition is met and does not perform any processing if the condition is not met.

      Syntax description

      t_if(Condition 1, Function 1)

      Parameter description

      Parameter
      Description
      Parameter Type
      Required
      Default Value
      Value Range
      condition
      Function expression whose return value is of bool type
      bool
      Yes
      -
      -
      function
      Function expression whose return value is of LOG type
      string
      Yes
      -
      -

      Example

      Example 1Raw log:
      {"condition": 1, "status": "500"}
      Processing rule:
      t_if(True, fields_set("new", 1))
      Processing result:
      {"new":"1","condition":"1","status":"500"}
      Example 2 Raw log:
      // If the value of `condition` is `1` (true), add a field `new` and assign value `1` to it.
      {"condition": 1, "status": "500"}
      Processing rule:
      t_if(v("condition"), fields_set("new", 1))
      Processing result:
      {"new":"1","condition":"1","status":"500"}

      Function t_if_not

      Function definition

      This function is used to execute a corresponding function if a condition is not met and does not perform any processing if the condition is met.

      Syntax description

      t_if_not(Condition 1, Function 1)

      Parameter description

      Parameter
      Description
      Parameter Type
      Required
      Default Value
      Value Range
      condition
      Function expression whose return value is of bool type
      bool
      Yes
      -
      -
      function
      Function expression whose return value is of LOG type
      string
      Yes
      -
      -

      Example

      Raw log:
      {"condition": 0, "status": "500"}
      Processing rule:
      t_if_not(v("condition"), fields_set("new", 1))
      Processing result:
      {"new":"1","condition":"0","status":"500"}

      Function t_if_else

      Function definition

      This function is used to execute a function based on the evaluation result of a condition.

      Syntax description

      t_if_else("Condition 1", Function 1, Function 2)

      Parameter description

      Parameter
      Description
      Parameter Type
      Required
      Default Value
      Value Range
      condition
      Function expression whose return value is of bool type
      bool
      Yes
      -
      -
      function
      Function expression whose return value is of LOG type
      string
      Yes
      -
      -
      function
      Function expression whose return value is of LOG type
      string
      Yes
      -
      -

      Example

      Raw log:
      {"condition": 1, "status": "500"}
      Processing rule:
      t_if_else(v("condition"), fields_set("new", 1), fields_set("new", 2))
      Processing result:
      {"new":"1","condition":"1","status":"500"}

      unction t_switch

      Function definition

      This function is used to execute different functions depending on whether branch conditions are met. If all conditions are not met, the data is deleted.

      Syntax description

      t_switch("Condition 1", Function 1, "Condition 2", Function 2, ...)

      Parameter description

      Parameter
      Description
      Parameter Type
      Required
      Default Value
      Value Range
      Variable parameter, which is a list of condition-function expression pairs
      Similar to a combination of multiple t_if functions. For more information, see Function t_if.
      -
      -
      -
      -

      Example

      Raw log:
      {"condition1": 0,"condition2": 1, "status": "500"}
      Processing rule:
      // If `condition1` is `1` (true), add a field `new` and assign value `1` to it. Here, `False` is returned for `condition1`, and therefore the `new` field (value: `1`) is not added; `True` is returned for `condition2`, and therefore the `new` field (value: `2`) is added.
      t_switch(v("condition1"), fields_set("new", 1), v("condition2"), fields_set("new", 2))
      Processing result:
      {"new":"2","condition1":"0","condition2":"1","status":"500"}
      
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