How to force a formatted DateTime to return a string? #558

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adam · 2025-12-29T15:26:55+01:00

adam commented

2025-12-29 15:26:55 +01:00

Originally created by @felipetofoli on GitHub (Dec 6, 2023).

First of all, thanks for this amazing lib! :)

I have to apply a specific format ("yyMMddhhmmss") to a DateTime and receive a string as the result. I tried multiple approaches, but I always receive an integer, instead of a string.
So my question is: How to force a formatted DateTime to return a string?

Example:

"BodyAsJson": {
    "timestamp": "{{ DateTime.UtcNow \"yyMMddhhmmss\" }}",
    "timestamp2": "{{ DynamicLinq.Expression 'DateTime.UtcNow.ToString(\"yyMMddhhmmss\")' }}",
    "timestamp3": "{{ String.Format (DateTime.UtcNow) \"yyMMddhhmmss\" }}",
}

The above JSON configuration returns the following result:

{
    "timestamp": 231205110312,
    "timestamp2": 231205110312,
    "timestamp3": 231205110312
}

The expected/desired result:

{
    "timestamp": "231205110312",
    "timestamp2": "231205110312",
    "timestamp3": "231205110312"
}

I already tried wrapping the configuration with double quotes, using String.Append to append an empty string (""), but I wasn't able to get the expected/desired result.

Please let me know if any other information is needed!
Thanks!

Originally created by @felipetofoli on GitHub (Dec 6, 2023). First of all, thanks for this amazing lib! :) I have to apply a specific format (`"yyMMddhhmmss"`) to a DateTime and receive a string as the result. I tried multiple approaches, but I always receive an integer, instead of a string. So my question is: How to force a formatted DateTime to return a string? Example: ```json "BodyAsJson": { "timestamp": "{{ DateTime.UtcNow \"yyMMddhhmmss\" }}", "timestamp2": "{{ DynamicLinq.Expression 'DateTime.UtcNow.ToString(\"yyMMddhhmmss\")' }}", "timestamp3": "{{ String.Format (DateTime.UtcNow) \"yyMMddhhmmss\" }}", } ``` The above JSON configuration returns the following result: ```json { "timestamp": 231205110312, "timestamp2": 231205110312, "timestamp3": 231205110312 } ``` The expected/desired result: ```json { "timestamp": "231205110312", "timestamp2": "231205110312", "timestamp3": "231205110312" } ```` I already tried wrapping the configuration with double quotes, using `String.Append` to append an empty string (`""`), but I wasn't able to get the expected/desired result. Please let me know if any other information is needed! Thanks!

adam added the question label 2025-12-29 15:26:55 +01:00

adam closed this issue

2025-12-29 15:26:55 +01:00

adam commented

2025-12-29 15:26:55 +01:00

@StefH commented on GitHub (Dec 6, 2023):

@felipetofoli
This looks the same as this issue:
https://github.com/WireMock-Net/WireMock.Net/issues/884

I think the only solution for you would be not to use BodyAsJson, but just Body and return the required json message as a string.

Like:

"{\n    \"timestamp\": \"{{ DateTime.UtcNow \\\"yyMMddhhmmss\\\" }}\",\n    \"timestamp2\": \"{{ DynamicLinq.Expression 'DateTime.UtcNow.ToString(\\\"yyMMddhhmmss\\\")' }}\",\n    \"timestamp3\": \"{{ String.Format (DateTime.UtcNow) \\\"yyMMddhhmmss\\\" }}\",\n}"

@StefH commented on GitHub (Dec 6, 2023): @felipetofoli This looks the same as this issue: https://github.com/WireMock-Net/WireMock.Net/issues/884 I think the only solution for you would be not to use `BodyAsJson`, but just `Body` and return the required json message as a string. Like: ``` c# "{\n \"timestamp\": \"{{ DateTime.UtcNow \\\"yyMMddhhmmss\\\" }}\",\n \"timestamp2\": \"{{ DynamicLinq.Expression 'DateTime.UtcNow.ToString(\\\"yyMMddhhmmss\\\")' }}\",\n \"timestamp3\": \"{{ String.Format (DateTime.UtcNow) \\\"yyMMddhhmmss\\\" }}\",\n}" ```

adam commented

2025-12-29 15:26:56 +01:00

@StefH commented on GitHub (Dec 6, 2023):

https://github.com/WireMock-Net/WireMock.Net/pull/1029

@StefH commented on GitHub (Dec 6, 2023): https://github.com/WireMock-Net/WireMock.Net/pull/1029

adam commented

2025-12-29 15:26:56 +01:00

@StefH commented on GitHub (Dec 7, 2023):

@felipetofoli is this ok for you?

@StefH commented on GitHub (Dec 7, 2023): @felipetofoli is this ok for you?

adam commented

2025-12-29 15:26:57 +01:00

@felipetofoli commented on GitHub (Dec 7, 2023):

Hi @StefH !
Thanks for the response!

Yes, the Body approach works for the JSON configuration.

I am thinking about using C# mappings instead (to avoid the inline configurations).

According to the other issues, the .WithTransformer(ReplaceNodeOptions.EvaluateAndTryToConvert) should do the trick, right?
Reference: https://github.com/WireMock-Net/WireMock.Net/issues/884#issuecomment-1693548031

Or should I use .WithTransformer(ReplaceNodeOptions.KeepString)?
Reference: https://github.com/WireMock-Net/WireMock.Net/issues/884#issuecomment-1432874211

@felipetofoli commented on GitHub (Dec 7, 2023): Hi @StefH ! Thanks for the response! Yes, the `Body` approach works for the JSON configuration. I am thinking about using C# mappings instead (to avoid the inline configurations). According to the other issues, the `.WithTransformer(ReplaceNodeOptions.EvaluateAndTryToConvert)` should do the trick, right? Reference: https://github.com/WireMock-Net/WireMock.Net/issues/884#issuecomment-1693548031 Or should I use `.WithTransformer(ReplaceNodeOptions.KeepString)`? Reference: https://github.com/WireMock-Net/WireMock.Net/issues/884#issuecomment-1432874211

adam commented

2025-12-29 15:26:58 +01:00

@StefH commented on GitHub (Dec 7, 2023):

I'm not 100% sure anymore if that enim option works as intended

So for now use c# mappings or a body as string.

@StefH commented on GitHub (Dec 7, 2023): I'm not 100% sure anymore if that enim option works as intended So for now use c# mappings or a body as string.

adam commented

2025-12-29 15:26:58 +01:00

@felipetofoli commented on GitHub (Dec 7, 2023):

@StefH, I've just tested the c# mappings, but they are returning a number either - instead of a string:

server
    .Given(Request
        .Create()
        .WithPath(new ExactMatcher("/datetime-test"))
        .UsingPost())
    .RespondWith(Response
        .Create()
        .WithHeader("Content-Type", "application/json")
        .WithBodyAsJson(new
        {
            timestamp = "{{ DateTime.UtcNow \"yyMMddhhmmss\" }}",
        })
        .WithTransformer());

Response:

{"timestamp":231207053817}

Is there any other configuration to do?

Thanks,

@felipetofoli commented on GitHub (Dec 7, 2023): @StefH, I've just tested the c# mappings, but they are returning a number either - instead of a string: ```csharp server .Given(Request .Create() .WithPath(new ExactMatcher("/datetime-test")) .UsingPost()) .RespondWith(Response .Create() .WithHeader("Content-Type", "application/json") .WithBodyAsJson(new { timestamp = "{{ DateTime.UtcNow \"yyMMddhhmmss\" }}", }) .WithTransformer()); ``` Response: ```json {"timestamp":231207053817} ``` Is there any other configuration to do? Thanks,

adam commented

2025-12-29 15:26:58 +01:00

@StefH commented on GitHub (Dec 7, 2023):

Sorry. In that case : use a string instead of json.

I need to think in how to change the internal logic.

@StefH commented on GitHub (Dec 7, 2023): Sorry. In that case : use a string instead of json. I need to think in how to change the internal logic.

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Reference: starred/WireMock.Net-wiremock#558