duanpu2272 2016-03-31 16:45
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当地图查找失败时,从模板返回解析错误

I have a series of templates that use generic map[string]string value in them. Something like

 <h1> You sent in {{.Field1}} and {{.Field2}} </h1> 

The payload will be: {"Field1": "Value1", "Field2": "Value2"}

Called as: err := tmpl.Execute(w, data); // data is map[string]string and was decoded from the payload

I cannot convert data to a struct as the templates and payload are determined at runtime. These templates are created by business users and I don't want to create a type for each template and change the backend every time there is a new template. Hence the desire to keep the map[string]string like solution.

The issue with the above design is that when a field used in the template is not passed in at runtime. When I execute the template, the missing fields return an empty string in the template. I would like to return an error if that happens.

So, I would like to know if there a way to make the template return a parse error when the map-lookup fails? Or is there a way to pass generic struct values with runtime error checking to a template that allows for dynamic payloads?

Thanks!

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  • dongping1922 2016-03-31 16:53
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    Using the "missingkey=error" option.

    tmpl := template.Must(template.New("").Option("missingkey=error").Parse(
          `<h1> You sent in {{.Field1}} and {{.Field2}} </h1>`))
    

    playground example

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