Is there a way to programmatically convert JSON to AVRO Schema?

问题

I need to create AVRO file but for that I need 2 things:

1) JSON

2) Avro Schema

From these 2 requirements - I have JSON:

{"web-app": {
  "servlet": [   
    {
      "servlet-name": "cofaxCDS",
      "servlet-class": "org.cofax.cds.CDSServlet",
      "init-param": {
        "configGlossary:installationAt": "Philadelphia, PA",
        "configGlossary:adminEmail": "ksm@pobox.com",
        "configGlossary:poweredBy": "Cofax",
        "configGlossary:poweredByIcon": "/images/cofax.gif",
        "configGlossary:staticPath": "/content/static",
        "templateProcessorClass": "org.cofax.WysiwygTemplate",
        "templateLoaderClass": "org.cofax.FilesTemplateLoader",
        "templatePath": "templates",
        "templateOverridePath": "",
        "defaultListTemplate": "listTemplate.htm",
        "defaultFileTemplate": "articleTemplate.htm",
        "useJSP": false,
        "jspListTemplate": "listTemplate.jsp",
        "jspFileTemplate": "articleTemplate.jsp",
        "cachePackageTagsTrack": 200,
        "cachePackageTagsStore": 200,
        "cachePackageTagsRefresh": 60,
        "cacheTemplatesTrack": 100,
        "cacheTemplatesStore": 50,
        "cacheTemplatesRefresh": 15,
        "cachePagesTrack": 200,
        "cachePagesStore": 100,
        "cachePagesRefresh": 10,
        "cachePagesDirtyRead": 10,
        "searchEngineListTemplate": "forSearchEnginesList.htm",
        "searchEngineFileTemplate": "forSearchEngines.htm",
        "searchEngineRobotsDb": "WEB-INF/robots.db",
        "useDataStore": true,
        "dataStoreClass": "org.cofax.SqlDataStore",
        "redirectionClass": "org.cofax.SqlRedirection",
        "dataStoreName": "cofax",
        "dataStoreDriver": "com.microsoft.jdbc.sqlserver.SQLServerDriver",
        "dataStoreUrl": "jdbc:microsoft:sqlserver://LOCALHOST:1433;DatabaseName=goon",
        "dataStoreUser": "sa",
        "dataStorePassword": "dataStoreTestQuery",
        "dataStoreTestQuery": "SET NOCOUNT ON;select test='test';",
        "dataStoreLogFile": "/usr/local/tomcat/logs/datastore.log",
        "dataStoreInitConns": 10,
        "dataStoreMaxConns": 100,
        "dataStoreConnUsageLimit": 100,
        "dataStoreLogLevel": "debug",
        "maxUrlLength": 500}},
    {
      "servlet-name": "cofaxEmail",
      "servlet-class": "org.cofax.cds.EmailServlet",
      "init-param": {
      "mailHost": "mail1",
      "mailHostOverride": "mail2"}},
    {
      "servlet-name": "cofaxAdmin",
      "servlet-class": "org.cofax.cds.AdminServlet"},

    {
      "servlet-name": "fileServlet",
      "servlet-class": "org.cofax.cds.FileServlet"},
    {
      "servlet-name": "cofaxTools",
      "servlet-class": "org.cofax.cms.CofaxToolsServlet",
      "init-param": {
        "templatePath": "toolstemplates/",
        "log": 1,
        "logLocation": "/usr/local/tomcat/logs/CofaxTools.log",
        "logMaxSize": "",
        "dataLog": 1,
        "dataLogLocation": "/usr/local/tomcat/logs/dataLog.log",
        "dataLogMaxSize": "",
        "removePageCache": "/content/admin/remove?cache=pages&id=",
        "removeTemplateCache": "/content/admin/remove?cache=templates&id=",
        "fileTransferFolder": "/usr/local/tomcat/webapps/content/fileTransferFolder",
        "lookInContext": 1,
        "adminGroupID": 4,
        "betaServer": true}}],
  "servlet-mapping": {
    "cofaxCDS": "/",
    "cofaxEmail": "/cofaxutil/aemail/*",
    "cofaxAdmin": "/admin/*",
    "fileServlet": "/static/*",
    "cofaxTools": "/tools/*"},

  "taglib": {
    "taglib-uri": "cofax.tld",
    "taglib-location": "/WEB-INF/tlds/cofax.tld"}}}

But how to create AVRO Schema based on it?

Looking for programatic way to do that since will have many schemas and can not create Avro Schema manually every time.

I checked 'avro-tools-1.8.1.jar' but that can not create Avro Schema from JSON directly.

Looking for a Jar or Python code that can create JSON -> Avro schema. It is ok if Data Types are not perfect (Strings, Integers and Floats are good enough for start).

回答1:

you can use Kite SDK util to infer avro schema from a json input.

https://github.com/kite-sdk/kite/blob/master/kite-data/kite-data-core/src/main/java/org/kitesdk/data/spi/JsonUtil.java#L539

Example:

    String json = "{\n" +
            "    \"id\": 1,\n" +
            "    \"name\": \"A green door\",\n" +
            "    \"price\": 12.50,\n" +
            "    \"tags\": [\"home\", \"green\"]\n" +
            "}\n"
            ;
    String avroSchema = JsonUtil.inferSchema(JsonUtil.parse(json), "myschema").toString();
    System.out.println(avroSchema);

Result:

{  
   "type":"record",
   "name":"myschema",
   "fields":[  
      {  
         "name":"id",
         "type":"int",
         "doc":"Type inferred from '1'"
      },
      {  
         "name":"name",
         "type":"string",
         "doc":"Type inferred from '\"A green door\"'"
      },
      {  
         "name":"price",
         "type":"double",
         "doc":"Type inferred from '12.5'"
      },
      {  
         "name":"tags",
         "type":{  
            "type":"array",
            "items":"string"
         },
         "doc":"Type inferred from '[\"home\",\"green\"]'"
      }
   ]
}

You can find the maven dependency here

回答2:

If you want to avoid creating a dedicated AVRO schema for every JSON format, you can use rec-avro package.

It allows you to take any python data structure, including parsed XML or JSON and store it in Avro without a need for a dedicated schema.

I tested it for python 3.

You can install it as pip3 install rec-avro or see the code and docs at https://github.com/bmizhen/rec-avro

I gave a json to avro example code here: https://stackoverflow.com/a/55444481/6654219

回答3:

This one works cool with a simple copy and paste of avro schema.

https://toolslick.com/generation/metadata/avro-schema-from-json

来源：https://stackoverflow.com/questions/46556614/is-there-a-way-to-programmatically-convert-json-to-avro-schema