Better handling of backtick in pattern (OpenAPITools#19358)

* use x-go-datatag in go client model template

* add logic to handle backtick

modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/AbstractGoCodegen.java

@@ -786,7 +786,43 @@ public ModelsMap postProcessModels(ModelsMap objs) {
                             cp.pattern.replace("\\", "\\\\").replaceAll("^/|/$", "") +
                             "\"");
                 }
+
+                // construct data tag in the template: x-go-datatag
+                // originl template
+                // `json:"{{{baseName}}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{{baseName}}}{{#isXmlAttribute}},attr{{/isXmlAttribute}}"{{/withXml}}{{#withValidate}} validate:"{{validate}}"{{/withValidate}}{{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}`
+                String goDataTag = "json:\"" + cp.baseName;
+                if (!cp.required) {
+                    goDataTag += ",omitempty";
+                }
+                goDataTag += "\"";
+
+                if (withXml) {
+                    goDataTag += " xml:" + "\"" + cp.baseName;
+                    if (cp.isXmlAttribute) {
+                        goDataTag += ",attr";
+                    }
+                    goDataTag += "\"";
+                }
+
+                // {{#withValidate}} validate:"{{validate}}"{{/withValidate}}
+                if (Boolean.parseBoolean(String.valueOf(additionalProperties.getOrDefault("withValidate", "false")))) {
+                    goDataTag += " validate:\"" + additionalProperties.getOrDefault("validate", "") + "\"";
+                }
+
+                // {{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}
+                if (StringUtils.isNotEmpty(String.valueOf(cp.vendorExtensions.getOrDefault("x-go-custom-tag", "")))) {
+                    goDataTag += " " + cp.vendorExtensions.get("x-go-custom-tag");
+                }
+
+                // if it contains backtick, wrap with " instead
+                if (goDataTag.contains("`")) {
+                    goDataTag = " \"" + goDataTag.replace("\"", "\\\"") + "\"";
+                } else {
+                    goDataTag = " `" + goDataTag + "`";
+                }
+                cp.vendorExtensions.put("x-go-datatag", goDataTag);
             }
+
             if (this instanceof GoClientCodegen && model.isEnum) {
                 imports.add(createMapping("import", "fmt"));
             }

modules/openapi-generator/src/main/resources/go/model_simple.mustache

@@ -20,7 +20,7 @@ type {{classname}} struct {
 {{#deprecated}}
 	// Deprecated
 {{/deprecated}}
-	{{name}} {{^required}}{{^isNullable}}{{^isArray}}{{^isFreeFormObject}}*{{/isFreeFormObject}}{{/isArray}}{{/isNullable}}{{/required}}{{{dataType}}} `json:"{{{baseName}}}{{^required}},omitempty{{/required}}"{{#withXml}} xml:"{{{baseName}}}{{#isXmlAttribute}},attr{{/isXmlAttribute}}"{{/withXml}}{{#withValidate}} validate:"{{validate}}"{{/withValidate}}{{#vendorExtensions.x-go-custom-tag}} {{{.}}}{{/vendorExtensions.x-go-custom-tag}}`
+	{{name}} {{^required}}{{^isNullable}}{{^isArray}}{{^isFreeFormObject}}*{{/isFreeFormObject}}{{/isArray}}{{/isNullable}}{{/required}}{{{dataType}}}{{{vendorExtensions.x-go-datatag}}}
 {{/vars}}
 {{#isAdditionalPropertiesTrue}}
 	AdditionalProperties map[string]interface{}

modules/openapi-generator/src/test/resources/3_0/go/petstore-with-fake-endpoints-models-for-testing-with-http-signature.yaml

@@ -1729,6 +1729,9 @@ components:
           description: A string starting with 'image_' (case insensitive) and one to three digits following i.e. Image_01.
           type: string
           pattern: '/^image_\d{1,3}$/i'
+        pattern_with_backtick:
+          type: string
+          pattern: "^$|^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$"
     EnumClass:
       type: string
       default: '-efg'

samples/openapi3/client/petstore/go/go-petstore/api/openapi.yaml

@@ -1683,6 +1683,10 @@ components:
             to three digits following i.e. Image_01.
           pattern: "/^image_\\d{1,3}$/i"
           type: string
+        pattern_with_backtick:
+          pattern: "^$|^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\\
+            .[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)*$"
+          type: string
       required:
       - byte
       - date

samples/openapi3/client/petstore/go/go-petstore/docs/FormatTest.md

@@ -19,6 +19,7 @@ Name | Type | Description | Notes
 **Password** | **string** |  | 
 **PatternWithDigits** | Pointer to **string** | A string that is a 10 digit number. Can have leading zeros. | [optional] 
 **PatternWithDigitsAndDelimiter** | Pointer to **string** | A string starting with 'image_' (case insensitive) and one to three digits following i.e. Image_01. | [optional] 
+**PatternWithBacktick** | Pointer to **string** |  | [optional] 
 
 ## Methods
 
@@ -394,6 +395,31 @@ SetPatternWithDigitsAndDelimiter sets PatternWithDigitsAndDelimiter field to giv
 
 HasPatternWithDigitsAndDelimiter returns a boolean if a field has been set.
 
+### GetPatternWithBacktick
+
+`func (o *FormatTest) GetPatternWithBacktick() string`
+
+GetPatternWithBacktick returns the PatternWithBacktick field if non-nil, zero value otherwise.
+
+### GetPatternWithBacktickOk
+
+`func (o *FormatTest) GetPatternWithBacktickOk() (*string, bool)`
+
+GetPatternWithBacktickOk returns a tuple with the PatternWithBacktick field if it's non-nil, zero value otherwise
+and a boolean to check if the value has been set.
+
+### SetPatternWithBacktick
+
+`func (o *FormatTest) SetPatternWithBacktick(v string)`
+
+SetPatternWithBacktick sets PatternWithBacktick field to given value.
+
+### HasPatternWithBacktick
+
+`func (o *FormatTest) HasPatternWithBacktick() bool`
+
+HasPatternWithBacktick returns a boolean if a field has been set.
+
 
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