Some Text
\"\n};\n\nconst comments = {\n \"list\": [\"not too bad\", \"pretty good\", \"awful\"]\n};\n\nconst user = {\n \"id\": 123,\n \"name\": \"John Doe\",\n \"email\": \"john.doe@nobody.com\"\n};\n\n// combine multiple objects into a single source object\nconst source = { post, comments, user };\n\nconst map = createMapper();\n\nmap(\"post.body\").to(\"blog.post.text\");\nmap(\"comments.list\").to(\"blog.post.comments\");\nmap(\"comments.list[0]\").to(\"blog.post.topComment\");\nmap(\"user.id\").to(\"blog.author.id\");\nmap(\"user.name\").to(\"blog.author.name\");\nmap(\"user.email\").to(\"blog.author.email\");\n\nconst result = map.execute(source);\n\nassert.deepEqual(result, {\n \"blog\": {\n \"post\":\n {\n \"text\": \"Some Text
\",\n \"comments\": [\"not too bad\", \"pretty good\", \"awful\"],\n \"topComment\": \"not too bad\"\n },\n \"author\": {\n \"id\": 123,\n \"name\": \"John Doe\",\n \"email\": \"john.doe@nobody.com\"\n }\n }\n});\n```\n\nAn existing object can be provided as the target object.\n\n```js\nconst createMapper = require(\"map-factory\");\nconst assert = require(\"assert\");\n\nconst source = {\n \"fieldName\": \"name1\",\n \"fieldId\": \"123\",\n \"fieldDescription\": \"description\"\n };\n\nconst destination = {\n \"existing\": \"data\"\n};\n\nconst map = createMapper();\nmap(\"fieldName\").to(\"field.name\");\nmap(\"fieldId\").to(\"field.id\");\n\nconst result = map.execute(source, destination);\n\nassert.deepEqual(result, {\n \"existing\": \"data\",\n \"field\": {\n \"name\": \"name1\",\n \"id\": \"123\"\n }\n});\n```\n\n#### Merge objects with multiple mappers\nThe other option is to decorate your existing data objects in a piece by piece fashion using the merge ability. Note that when using a named mapper like ```postMapper``` the code reads better when you use the explicit ```map()``` method.\n\n```js\nconst createMapper = require(\"map-factory\");\nconst assert = require(\"assert\");\n\n// assume the following inputs\nconst post = {\n \"body\": \"Some Text
\"\n};\n\nconst comments = {\n \"list\": [\"not too bad\", \"pretty good\", \"awful\"]\n};\n\nconst user = {\n \"id\": 123,\n \"name\": \"John Doe\",\n \"email\": \"john.doe@nobody.com\"\n};\n\nconst postMapper = createMapper();\nconst commentMapper = createMapper();\nconst authorMapper = createMapper();\n\npostMapper\n .map(\"body\").to(\"blog.post.text\");\n\ncommentMapper\n .map(\"list\").to(\"blog.post.comments\")\n .map(\"list[0]\").to(\"blog.post.topComment\");\n\nauthorMapper\n .map(\"id\").to(\"blog.author.id\")\n .map(\"name\").to(\"blog.author.name\")\n .map(\"email\").to(\"blog.author.email\");\n\nlet result = postMapper.execute(post);\nresult = commentMapper.execute(comments, result);\nresult = authorMapper.execute(user, result);\n\nassert.deepEqual(result, {\n \"blog\": {\n \"post\": {\n \"text\": \"Some Text
\",\n \"comments\": [\n \"not too bad\",\n \"pretty good\",\n \"awful\"\n ],\n \"topComment\": \"not too bad\"\n },\n \"author\": {\n \"id\": 123,\n \"name\": \"John Doe\",\n \"email\": \"john.doe@nobody.com\"\n }\n }\n});\n```\n\nThe above approach appears untidy when compared with combining the data into a single object but it is useful in situations where your mapping logic is distributed.\nFor example, a mapper used within a class may build its map in the constructor and execute the mapper in a method.\n\n```js\nconst createMapper = require(\"map-factory\");\nconst assert = require(\"assert\");\nconst BlogRepo = require(\"./artifacts/mock-blog-repo\");\n\nclass BlogService {\n\n constructor(blogRepos) {\n this.blogRepos = blogRepos;\n\n // initialise mapper\n this.authorMapper = createMapper()\n .map(\"id\").to(\"blog.author.id\")\n .map(\"name\").to(\"blog.author.name\")\n .map(\"email\").to(\"blog.author.email\");\n }\n\n // Here post is created somewhere else and we are extending it with user information\n decorateBlogPostWithAuthor(userId, post) {\n return this.blogRepos.getUser(userId)\n .then(user => this.authorMapper.execute(user, post));\n }\n\n}\n\nconst blogService = new BlogService(new BlogRepo());\n\nconst post = {\n \"blog\": {\n \"post\": {\n \"id\": 10,\n \"title\": \"Foo bar baz\",\n \"post\": \"Foo bar baz
Foo bar baz