Is Match formatter

Choose between two outputs based on whether a value matches a regular expression.

The Is Match formatter evaluates a regular expression against the placeholder value and outputs one of two formats. Apply it explicitly with the name ismatch. The expression goes in the options, in parentheses; the format provides the match output and the no-match output, separated by the split character. Both the match and no-match output are required.

To use braces and parentheses as character literals in your pattern, escape them with a backslash. For example, \{, \}, \(, \).

You can configure settings on the formatter instance. Set the RegexOptions (for example, IgnoreCase) to control matching. Change the split character or the placeholder name for matches (the default is m). Refer to Configure Smart Strings for more information on formatter configuration.

flowchart TD
    full["{value:ismatch(regex):Match output|No match output}"]

    full --> p1["value"]
    full --> p2["ismatch"]
    full --> p3["regex"]
    full --> p4["Match output|No match output"]

    p1 --> d1["Any value"]
    p2 --> d2["Formatter name: ismatch"]
    p3 --> d3["Regular expression"]
    p4 --> d4["Outputs:<br/>match, then no-match"]

    classDef code   fill:#F5F5F5,stroke:#BDBDBD,color:#111;
    classDef orange fill:none,stroke:none,color:#F37021;
    classDef green  fill:none,stroke:none,color:#67BC6B;
    classDef pink   fill:none,stroke:none,color:#EB417A;
    classDef purple fill:none,stroke:none,color:#765BA7;

    class full code;
    class p1,d1 orange;
    class p2,d2 green;
    class p3,d3 pink;
    class p4,d4 purple;

    linkStyle default stroke:#2196F3,stroke-width:1.5px;

The first format is used when the value matches; the second is used otherwise. You can output the regular expression’s matching groups with a special placeholder named m: {m[0]} is the whole match and {m[1]}, {m[2]}, and so on are the captured groups.

Combine it with the List formatter to test each item in a collection:

Additional resources

• List formatter
• Choose formatter
• Smart Strings