{"id":1436,"date":"2016-04-14T15:32:57","date_gmt":"2016-04-14T19:32:57","guid":{"rendered":"http:\/\/codinggorilla.domemtech.com\/?p=1436"},"modified":"2016-06-08T11:30:57","modified_gmt":"2016-06-08T15:30:57","slug":"mongo-restheart-and-dokku","status":"publish","type":"post","link":"http:\/\/165.227.223.229\/index.php\/2016\/04\/14\/mongo-restheart-and-dokku\/","title":{"rendered":"Mongo, Restheart, and Dokku"},"content":{"rendered":"

Mongo<\/a> is a popular NoSQL<\/a> database nowadays. It has several advantages compared to relational databases<\/a>\u00c2\u00a0(schema-less, key-value store<\/a>, scalable, distributed, propagated consistency<\/a>) but the main advantage, IMHO, is that JSON is the lingua franca<\/em> for the data structures it stores and the queries you\u00c2\u00a0use. JSON is a nice, simple data structure representation. It can be easily passed between the database and the application; and it can be converted to\/from a string and an object in the native language you use. Mongo has many native-language APIs available for interfacing your application with the database, so you should be able to connect your application with Mongo.<\/p>\n

Unfortunately, Xamarin Forms applications, written in C#, are Portable Class Library (PCL)<\/a>\u00c2\u00a0applications, and the C# API for Mongo<\/a>\u00c2\u00a0can’t work.\u00c2\u00a0Unfortunately, PCL apps and libraries can only link with other PCL libraries that have\u00c2\u00a0the same or additional target platforms<\/em>. So, a PCL app that is targeting Windows, Android, and iOS cannot link with a library that only targets Windows, or only Android, or only iOS.<\/p>\n

However, all is not lost.\u00c2\u00a0Restheart<\/a> is an open source REST API server for Mongo databases. You can easily write a layer to encapsulate the calls that you need to access your Mongo database. There aren’t many functions you have to write beyond the usual CRUD<\/a>, and the signatures for the method are just strings.<\/p>\n

Setup<\/h3>\n

The installations instructions<\/a> are on the Mongo.org website.\u00c2\u00a0Get the latest production<\/a> version of Mongo. Then, execute the installation file. After it completes, create a directory for the database.<\/p>\n

md data\/db<\/pre>\n
To run Mongo, type<\/p>\n
mongod --dbpath data\/db<\/pre>\n
To set up Restheart, either copy the latest from Restheart.org<\/a>, or clone the git repository for Restheart<\/a>. If you are going to build it from scratch, you will need Maven, Java, and various other tools. Note, I highly recommend you build Restheart\u00c2\u00a0from git because the documentation is quite poor, and the only really good way to understand the server is to debug it.<\/p>\n
To run Restheart, type\u00c2\u00a0java -jar .\/restheart\/target\/<\/em>restheart.jar<\/em>, or the appropriate jar file.\u00c2\u00a0<\/em>You can specify a configuration file for Restheart\u00c2\u00a0as a parameter when executing the jar.<\/p>\n
CRUD<\/h3>\n
In a SQL database, data are stored in tables<\/a>. In Mongo, data are stored in a collection<\/a>. As with SQL, Mongo has CRUD<\/a> statements for access to the database.\u00c2\u00a0The equivalent in Mongo of a row in a SQL table is a document<\/a>, and is simply a JSON string. A projection<\/a> of a JSON structure is equivalent to a projection in SQL. If you convert the JSON into a Newtonsoft JObject, you can make a projection of one key\/value pair using the [] operator. As in SQL, an index can be created to improve search time.<\/p>\n
Examples<\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n
\n
SQL Op<\/h6>\n<\/td>\n
\n
Operation<\/h6>\n<\/td>\n
\n
Example<\/h6>\n<\/td>\n
\n
Example in Mongo shell<\/h6>\n<\/td>\n
\n
Example in Restheart<\/h6>\n<\/td>\n<\/tr>\n
\n
\u00c2\u00a0Create database<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Create a database named db1.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Create a database named db1.<\/h6>\n<\/td>\n
\n
use db1<\/h6>\n
NOTE: you need to insert a collection to actually create the database while using the Mongo shell.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0PUT<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/<\/a><\/h6>\n
NOTE: Do not set data or you will create a record with that data in the database. It can’t be deleted!<\/h6>\n<\/td>\n<\/tr>\n
\n
Create table<\/h6>\n<\/td>\n
\n
Create collection<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Create a collection named “col”.<\/h6>\n<\/td>\n
\n
db.createCollection(“col”)<\/a><\/h6>\n<\/td>\n
\n
PUT<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col<\/a><\/h6>\n<\/td>\n<\/tr>\n
\n
Insert a row in a table<\/h6>\n<\/td>\n
\n
Insert a document in a collecton<\/h6>\n<\/td>\n
\n
Insert {“a1″:”b1”} in collection col.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0db.col.insert({“a1″:”b1”})<\/a><\/h6>\n<\/td>\n
\n
POST<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col<\/a><\/h6>\n
payload is {“a1″:”b1”}<\/a><\/h6>\n
header is Content-Type: application\/json<\/a><\/h6>\n
NOTE: The record type\/value doesn’t have to be unique. So, you can insert duplicates if you like.<\/h6>\n<\/td>\n<\/tr>\n
\n
Read a row<\/h6>\n<\/td>\n
\n
Read a document<\/h6>\n<\/td>\n
\n
Find {} — find all records in collection col.<\/h6>\n<\/td>\n
\n
db.col.find({})<\/a><\/h6>\n
or just db.col.find()<\/h6>\n<\/td>\n
\n
GET<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col<\/a><\/h6>\n
header is Content-Type: application\/json<\/a><\/h6>\n<\/td>\n<\/tr>\n
\n
Read a row<\/h6>\n<\/td>\n
\n
Read a document<\/h6>\n<\/td>\n
\n
Find { “a1” : <value> } — find all records with key a1 in collection col.<\/h6>\n<\/td>\n
\n
db.col.find({“a1”:{$regex : “.*” }})<\/a><\/h6>\n<\/td>\n
\n
GET<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col?filter={“a1″:{$regex:”.*”}}<\/a><\/h6>\n
NOTE: Make sure to note the correct syntax. The Restheart arg parser is very, very poor. E.g., using parentheses instead of equal sign:<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col?filter={“a1″:{$regex:”.*”}}<\/a><\/h6>\n
This will return all records with a1, which is not what you intended!<\/h6>\n
To limit the find to the “first” record (whatever that means), add ‘&pagelimit=1’ to the args of the GET url.<\/h6>\n<\/td>\n<\/tr>\n
\n
Read a row<\/h6>\n<\/td>\n
\n
Read a document with projection<\/h6>\n<\/td>\n
\n
Find { “a1” : <value> } — find all records with key a1 in collection col, but only show keys of “cc”. For example, suppose there is one record, {{“aa”:”bb”}, {“cc”:”dd”}}. Return {“cc”:”dd”}.<\/h6>\n<\/td>\n
\n
db.col.find({“aa”:{$regex : “.*” }})<\/a>.projection({“cc”:1})<\/h6>\n<\/td>\n
\n
http:\/\/localhost:8080\/db1\/col?filter={“aa”:{$regex:”.*”}}&keys={“cc”:1}<\/a><\/h6>\n<\/td>\n<\/tr>\n
\n
\u00c2\u00a0Update a row<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Update a document<\/h6>\n<\/td>\n
\n
Update {“a1″:”*.”} to {“a1″:”asdf”}<\/h6>\n<\/td>\n
\n
db.col.update({“a1″:{$regex:”.*”}},{“a1″:”xx”})<\/a><\/h6>\n<\/td>\n
\n
PATCH<\/a><\/h6>\n
http:\/\/localhost:8080\/tb3\/col\/*?filter={“a1″:”.*”}<\/a><\/h6>\n
header is Content-Type: application\/json<\/a><\/h6>\n
payload is {“a1″:”asdf”}<\/a><\/h6>\n<\/td>\n<\/tr>\n
\n
\u00c2\u00a0Delete a row<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Delete a document<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Delete a record with a particular key\/value,\u00c2\u00a0{ “a1” : <value> }.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0db.col.remove({“a1″:{$regex:”.*”}})<\/a><\/h6>\n<\/td>\n
\n
\u00c2\u00a0DELETE<\/a><\/h6>\n
http:\/\/localhost:8080\/db1\/col\/*?filter={“aa”:{$regex:”.*”}}<\/a><\/h6>\n<\/td>\n<\/tr>\n
\n
\u00c2\u00a0Delete a table<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Delete a collection<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Nuke an entire collection col.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0db.col.drop()<\/a><\/h6>\n<\/td>\n
\n
\u00c2\u00a0DELETE<\/h6>\n
http:\/\/localhost:8080\/db1\/col<\/h6>\n<\/td>\n<\/tr>\n
\n
\u00c2\u00a0Delete database<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Delete database<\/h6>\n<\/td>\n
\n
\u00c2\u00a0Nuke the entire database db1.<\/h6>\n<\/td>\n
\n
\u00c2\u00a0db.dropDatabase()<\/a><\/h6>\n<\/td>\n
\n
\u00c2\u00a0DELETE<\/h6>\n
header contains If-Match:<the id of the database><\/em>, e.g., 570e3dc71d9563251070fab3<\/h6>\n
http:\/\/localhost:8080\/tb1\/<\/h6>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
 <\/p>\n
NOTE: Restheart normally requires an “ETag” header entry, i.e., “If-Match: 570e3dc71d9563251070fab3”, where that number is an ID of the record to delete. You can turn off ETag checking in a configuration file, which you can specify on the java command line.<\/p>\n
To get a value, you will have to parse the json\u00c2\u00a0for the field of interest. You can use projection to help you with that.<\/p>\n
Running Mongo and Restheart on Dokku<\/h2>\n
To run a Mongo database and a Restheart server on Dokku, you can get a copy of my Github example, then modify it for your needs. The example is here<\/a>.<\/p>\n
References<\/h2>\n
https:\/\/softinstigate.atlassian.net\/wiki\/display\/RH\/Installation+and+Setup#InstallationandSetup-7.3.MongoDBauthenticationwithjustenoughpermissionsauth-with-jep<\/p>\n
https:\/\/softinstigate.atlassian.net\/wiki\/display\/RH\/Query+Documents<\/p>\n
http:\/\/www.tutorialspoint.com\/mongodb\/mongodb_query_document.htm<\/p>\n
https:\/\/docs.mongodb.org\/manual\/reference\/method\/db.collection.find\/<\/p>\n
https:\/\/www.mongodb.org\/downloads#production<\/p>\n
http:\/\/www.codeproject.com\/Articles\/1087008\/Mongo-DB-Tutorial-and-Mapping-of-SQL-and-Mongo-DB<\/p>\n
http:\/\/stackoverflow.com\/questions\/tagged\/restheart<\/p>\n
https:\/\/en.wikipedia.org\/wiki\/MongoDB<\/p>\n
 <\/p>\n","protected":false},"excerpt":{"rendered":"
Mongo is a popular NoSQL database nowadays. It has several advantages compared to relational databases\u00c2\u00a0(schema-less, key-value store, scalable, distributed, propagated consistency) but the main advantage, IMHO, is that JSON is the lingua franca for the data structures it stores and the queries you\u00c2\u00a0use. JSON is a nice, simple data structure representation. It can be easily … <\/p>\n
Continue reading “Mongo, Restheart, and Dokku”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[],"tags":[],"_links":{"self":[{"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/posts\/1436"}],"collection":[{"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/comments?post=1436"}],"version-history":[{"count":0,"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/posts\/1436\/revisions"}],"wp:attachment":[{"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/media?parent=1436"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/categories?post=1436"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/165.227.223.229\/index.php\/wp-json\/wp\/v2\/tags?post=1436"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}