{"id":207900,"date":"2025-07-08T11:02:12","date_gmt":"2025-07-08T03:02:12","guid":{"rendered":"https:\/\/server.hk\/cnblog\/207900\/"},"modified":"2025-07-08T11:02:12","modified_gmt":"2025-07-08T03:02:12","slug":"%e5%a6%82%e4%bd%95%e4%bd%bf%e7%94%a8json%e5%ad%97%e7%ac%a6%e4%b8%b2%e5%80%bc%e8%8e%b7%e5%8f%96iota%e5%80%bc%ef%bc%9f","status":"publish","type":"post","link":"https:\/\/server.hk\/cnblog\/207900\/","title":{"rendered":"\u5982\u4f55\u4f7f\u7528json\u5b57\u7b26\u4e32\u503c\u83b7\u53d6iota\u503c\uff1f"},"content":{"rendered":"<p><b><\/b> <\/p>\n<p>\u5f53\u524d\u4f4d\u7f6e\uff1a <span>&gt;<\/span> <span>&gt;<\/span> <span>&gt;<\/span> <span>&gt;<\/span> <span>\u5982\u4f55\u4f7f\u7528json\u5b57\u7b26\u4e32\u503c\u83b7\u53d6iota\u503c\uff1f<\/span><\/p>\n<p><span>\u6765\u6e90\uff1astackoverflow<\/span><br \/>\n<span>2024-04-26 16:24:38<\/span><br \/>\n<span><i><\/i>0\u6d4f\u89c8<\/span><br \/>\n<span style=\"cursor: pointer\"><i><\/i>\u6536\u85cf<\/span> <\/p>\n<p>\u201c\u7eb5\u6709\u75be\u98ce\u6765\uff0c\u4eba\u751f\u4e0d\u8a00\u5f03\u201d\uff0c\u8fd9\u53e5\u8bdd\u9001\u7ed9\u6b63\u5728\u5b66\u4e60<span style=\"color: #FF6600;, Helvetica, Arial, sans-serif;font-size: 14px;background-color: #FFFFFF\">Golang<\/span>\u7684\u670b\u53cb\u4eec\uff0c\u4e5f\u5e0c\u671b\u5728\u9605\u8bfb\u672c\u6587<span style=\"color: #FF6600;, Helvetica, Arial, sans-serif;font-size: 14px;background-color: #FFFFFF\">\u300a\u5982\u4f55\u4f7f\u7528json\u5b57\u7b26\u4e32\u503c\u83b7\u53d6iota\u503c\uff1f\u300b<\/span>\u540e\uff0c\u80fd\u591f\u771f\u7684\u5e2e\u52a9\u5230\u5927\u5bb6\u3002\u6211\u4e5f\u4f1a\u5728\u540e\u7eed\u7684\u6587\u7ae0\u4e2d\uff0c\u9646\u7eed\u66f4\u65b0<span style=\"color: #FF6600;, Helvetica, Arial, sans-serif;font-size: 14px;background-color: #FFFFFF\">Golang<\/span>\u76f8\u5173\u7684\u6280\u672f\u6587\u7ae0\uff0c\u6709\u597d\u7684\u5efa\u8bae\u6b22\u8fce\u5927\u5bb6\u5728\u8bc4\u8bba\u7559\u8a00\uff0c\u975e\u5e38\u611f\u8c22\uff01<\/p>\n<p> \u95ee\u9898\u5185\u5bb9<br \/>\n <\/p>\n<p>\u6211\u6709\u4e00\u4e2a constutil \u5305\uff0c\u5176\u4e2d\u4f7f\u7528 iota \u5b9a\u4e49\u4e86\u4e00\u4e9b const \u503c\u3002<\/p>\n<pre>package constutil\n\ntype usertype uint\n\nconst (\n    free usertype = iota + 1\n    premium usertype\n    ...\n)<\/pre>\n<p>\u4ece <code>json<\/code> \u6211\u5c06\u5f97\u5230 <code>{\"user\": \"premium\", ...}<\/code>\u3002\u73b0\u5728\u6211\u9700\u8981\u4fdd\u5b58\u7528\u6237\u7684\u503c\uff0c\u4f8b\u5982 <code>premium<\/code> \u5b83\u662f <code>2<\/code>\u3002\u6211\u8bd5\u56fe\u83b7\u53d6\u8fd9\u6837\u7684\u503c\uff1a<\/p>\n<pre>constutil.(req.User)<\/pre>\n<p>\u4f46\u5b83\u4e0d\u8d77\u4f5c\u7528\uff0c\u56e0\u4e3a <code>req.user<\/code> \u8fd4\u56de <code>string<\/code>\uff0c\u5982\uff1a<code>\"premium\"<\/code>\u3002<\/p>\n<p>\u6211\u53ef\u4ee5\u4f7f\u7528 <code>map[string]uint<\/code> \u6765\u5b8c\u6210\u3002\u4f46\u662f\u6709\u6ca1\u6709\u529e\u6cd5\u4f7f\u7528 <code>iota<\/code> \u6765\u505a\u5230\u8fd9\u4e00\u70b9\uff1f<\/p>\n<p> <\/p>\n<h2>\u89e3\u51b3\u65b9\u6848<\/h2>\n<p> <\/p>\n<p>\u4e0d\u8981\u8ba4\u4e3a <code>iota<\/code> \u503c\u548c\u5b57\u7b26\u4e32\u4e4b\u95f4\u6709\u4efb\u4f55\u5185\u7f6e\u7684\u6620\u5c04\u65b9\u5f0f\u3002\u6709\u4e00\u4e9b\u5de5\u5177\u53ef\u4ee5\u751f\u6210\u7528\u4e8e\u8fdb\u884c\u6620\u5c04\u7684\u4ee3\u7801\u3002<\/p>\n<p>\u6211\u4e5f\u9047\u5230\u8fc7\u7c7b\u4f3c\u7684\u60c5\u51b5\uff0c\u5f53\u6211\u4e0d\u60f3\u4f9d\u8d56\u751f\u6210\u5668\u6216\u5176\u4ed6\u5de5\u5177\u65f6\uff0c\u6211\u5c31\u505a\u4e86\u8fd9\u6837\u7684\u4e8b\u60c5\u3002\u5e0c\u671b\u5b83\u53ef\u4ee5\u4f5c\u4e3a\u67d0\u4e9b\u4e8b\u60c5\u7684\u5f00\u59cb\u3002<\/p>\n<\/p>\n<pre>package main\n\nimport (\n    \"encoding\/json\"\n    \"fmt\"\n)\n\ntype UserType uint\n\nconst (\n    UserTypeFree UserType = iota\n    UserTypePremium\n)\n\nvar UserTypeToString = map[UserType]string{\n    UserTypeFree:    \"Free\",\n    UserTypePremium: \"Premium\",\n}\n\nvar UserTypeFromString = map[string]UserType{\n    \"Free\":    UserTypeFree,\n    \"Premium\": UserTypePremium,\n}\n\nfunc (ut UserType) String() string {\n    if s, ok := UserTypeToString[ut]; ok {\n        return s\n    }\n    return \"unknown\"\n}\n\nfunc (ut UserType) MarshalJSON() ([]byte, error) {\n    if s, ok := UserTypeToString[ut]; ok {\n        return json.Marshal(s)\n    }\n    return nil, fmt.Errorf(\"unknown user type %d\", ut)\n}\n\nfunc (ut *UserType) UnmarshalJSON(text []byte) error {\n    var s string\n    if err := json.Unmarshal(text, &amp;s); err != nil {\n        return err\n    }\n    var v UserType\n    var ok bool\n    if v, ok = UserTypeFromString[s]; !ok {\n        return fmt.Errorf(\"unknown user type %s\", s)\n    }\n    *ut = v\n    return nil\n}\n\nfunc main() {\n    var ut UserType\n\n    json.Unmarshal([]byte(`\"Free\"`), &amp;ut)\n\n    fmt.Printf(\"%#v %v \\n\", ut, ut)\n\n    b, _ := json.Marshal(ut)\n\n    fmt.Printf(\"%v\\n\", string(b))\n\n}\n<\/pre>\n<p>\u5230\u8fd9\u91cc\uff0c\u6211\u4eec\u4e5f\u5c31\u8bb2\u5b8c\u4e86\u300a\u5982\u4f55\u4f7f\u7528json\u5b57\u7b26\u4e32\u503c\u83b7\u53d6iota\u503c\uff1f\u300b\u7684\u5185\u5bb9\u4e86\u3002\u4e2a\u4eba\u8ba4\u4e3a\uff0c\u57fa\u7840\u77e5\u8bc6\u7684\u5b66\u4e60\u548c\u5de9\u56fa\uff0c\u662f\u4e3a\u4e86\u66f4\u597d\u7684\u5c06\u5176\u8fd0\u7528\u5230\u9879\u76ee\u4e2d\uff0c\u6b22\u8fce\u5173\u6ce8\u516c\u4f17\u53f7\uff0c\u5e26\u4f60\u4e86\u89e3\u66f4\u591a\u5173\u4e8e\u7684\u77e5\u8bc6\u70b9\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5f53\u524d\u4f4d\u7f6e\uff1a &gt; &gt; &#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4925],"tags":[],"class_list":["post-207900","post","type-post","status-publish","format-standard","hentry","category-4925"],"_links":{"self":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/207900","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/comments?post=207900"}],"version-history":[{"count":0,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/posts\/207900\/revisions"}],"wp:attachment":[{"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/media?parent=207900"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/categories?post=207900"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/server.hk\/cnblog\/wp-json\/wp\/v2\/tags?post=207900"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}