Generate a migration from a content type

content-type.json

{
  "name": "What is a collection",
  "description": null,
  "displayField": "plainText",
  "fields": [
    {
      "id": "plainText",
      "name": "plainText",
      "type": "Text",
      "localized": false,
      "required": false,
      "validations": [],
      "disabled": false,
      "omitted": false
    },
    {
      "id": "markdown",
      "name": "markdown",
      "type": "Text",
      "localized": false,
      "required": false,
      "validations": [],
      "disabled": false,
      "omitted": false
    },
    {
      "id": "number",
      "name": "number",
      "type": "Number",
      "localized": false,
      "required": false,
      "validations": [],
      "disabled": false,
      "omitted": false
    },
    {
      "id": "date",
      "name": "date",
      "type": "Date",
      "localized": false,
      "required": false,
      "validations": [],
      "disabled": false,
      "omitted": false
    },
    {
      "id": "switch",
      "name": "switch",
      "type": "Boolean",
      "localized": false,
      "required": false,
      "validations": [],
      "disabled": false,
      "omitted": false
    }
  ],
  "sys": {
    "space": {
      "sys": {
        "type": "Link",
        "linkType": "Space",
        "id": "zd2pt2bc3cts"
      }
    },
    "id": "what-is-a-collection",
    "type": "ContentType",
    "createdAt": "2017-09-12T08:51:02.797Z",
    "updatedAt": "2017-09-12T12:15:07.715Z",
    "createdBy": {
      "sys": {
        "type": "Link",
        "linkType": "User",
        "id": "2T4JQZGOuHn2xzFE3Nht1J"
      }
    },
    "updatedBy": {
      "sys": {
        "type": "Link",
        "linkType": "User",
        "id": "6c10tlsIDlE3qvnNoTwYa5"
      }
    },
    "publishedCounter": 2,
    "version": 4,
    "publishedBy": {
      "sys": {
        "type": "Link",
        "linkType": "User",
        "id": "6c10tlsIDlE3qvnNoTwYa5"
      }
    },
    "publishedVersion": 3,
    "firstPublishedAt": "2017-09-12T08:51:03.261Z",
    "publishedAt": "2017-09-12T12:15:07.715Z"
  }
}

index.js

'use strict';

const contentType = require('./content-type.json');
// const { namedTypes: n, builders: b } = require('ast-types');
const recast = require('recast');
const camelCase = require('camelcase');
const b = recast.types.builders;
const _ = require('lodash');
const toAst = require('to-ast');
const prettier = require('prettier');


const wrapMigrationWithBase = function (blockStatement) {
  const migration = b.program([
    b.expressionStatement(
      b.assignmentExpression(
        '=',
        b.memberExpression(
          b.identifier('module'),
          b.identifier('exports')
        ),
        b.functionExpression(
          null,
          [b.identifier('migration')],
          blockStatement
        )
      )
    )
  ])

  return migration
}

const createCallChain = function (base, chain) {
  if (chain.length === 0) {
    return base;
  }

  const [identifier, value] = chain[0];
  const rest = chain.slice(1);

  return createCallChain(b.callExpression(
    b.memberExpression(
      base,
      b.identifier(identifier)
    ),
    [toAst(value)]
  ), rest)
};

const createContentType = function (ct) {
  const id = ct.sys.id;
  const { name, description, displayField } = ct;
  const chain = [
    ['name', name],
    ['description', description],
    ['displayField', displayField]
  ].filter(([id, value]) => value !== null);

  const variableName = camelCase(id);

  const createCallExpression = b.callExpression(
    b.memberExpression(
      b.identifier('migration'),
      b.identifier('createContentType')
    ),
    [b.literal(id)]
  );

  const callChain = createCallChain(createCallExpression, chain);

  const withDeclaration = b.variableDeclaration(
    'const',
    [
      b.variableDeclarator(
        b.identifier(variableName),
        callChain
      )
    ]
  )

  return withDeclaration
}

const createField = function (ctId, field) {
  const fieldId = field.id;
  const ctVariable = camelCase(ctId);

  const chain = Object.keys(_.omit(field, 'id')).map((key) => {
    return [key, field[key]];
  });

  return createCallChain(
    b.callExpression(
      b.memberExpression(
        b.identifier(ctVariable),
        b.identifier('createField')
      ),
      [b.literal(fieldId)]
    ),
    chain
  )
}

const fieldCreators = contentType.fields.map((field) => {
  return b.expressionStatement(createField(contentType.sys.id, field));
})

const blockContents = [createContentType(contentType)].concat(fieldCreators);
const migration = wrapMigrationWithBase(b.blockStatement(blockContents));

const output = recast.prettyPrint(migration, { tabWidth: 2 }).code;

console.log(prettier.format(output))

output.js

module.exports = function(migration) {
  const whatIsACollection = migration
    .createContentType("what-is-a-collection")
    .name("What is a collection")
    .displayField("plainText");
  whatIsACollection
    .createField("plainText")
    .name("plainText")
    .type("Text")
    .localized(false)
    .required(false)
    .validations([])
    .disabled(false)
    .omitted(false);
  whatIsACollection
    .createField("markdown")
    .name("markdown")
    .type("Text")
    .localized(false)
    .required(false)
    .validations([])
    .disabled(false)
    .omitted(false);
  whatIsACollection
    .createField("number")
    .name("number")
    .type("Number")
    .localized(false)
    .required(false)
    .validations([])
    .disabled(false)
    .omitted(false);
  whatIsACollection
    .createField("date")
    .name("date")
    .type("Date")
    .localized(false)
    .required(false)
    .validations([])
    .disabled(false)
    .omitted(false);
  whatIsACollection
    .createField("switch")
    .name("switch")
    .type("Boolean")
    .localized(false)
    .required(false)
    .validations([])
    .disabled(false)
    .omitted(false);
};

package.json

{
  "name": "content-type-to-migration",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "ast-types": "^0.9.12",
    "camelcase": "^4.1.0",
    "lodash": "^4.17.4",
    "prettier": "^1.6.1",
    "recast": "^0.12.6",
    "to-ast": "^1.0.0"
  }
}