@dictadata/mssql-junction 0.9.x

MSSQLJunction provides a normalized, plug-in interface to access MSSQL Server data sources. MSSQLJunction is a storage plugin for use with @dictadata/storage-junctions and related projects @dictadata/storage-stracts ETL command line utility and @dictadata/storage-node API Server.

Installation

npm install @dictadata/mssql-junctions

Plugin Initialization

Import the Storage Junctions library and the MSSQL Junction plugin. Then register MSSQL Junction with the Storage Junctions' Storage module. This will register MSSQL Junction for use with storage model "mssql".

const { Storage } = require("@dictadata/storage-junctions");
const MSSQLJunction = require("@dictadata/mssql-junction");

Storage.Junctions.use("mssql", MSSQLJunction);

Creating an instance of MSSQLJunction

Create an instance of MSSQLJunction class.

let junction = Storage.activate(smt, options);

SMT

MSSQLJunction constructor takes an SMT, Storage Memory Trace, with the address of the data source. SMT can be a string or object. The SMT string format is "model|locus|schema|key" which for MSSQLJunction is "mssql|server=localhost;database=db_name|table_name|*".

// SMT string
let smt = "mssql|server=dev.dictadata.net;database=storage_node|foo_schema|=Foo"

// SMT object
let SMT = {
  model: "mssql",
  locus: "server=dev.dictadata.net;database=storage_node",
  schema: "foo_schema",
  key: "*" // all rows
}

MSSQLJunction Options

MSSQLJunction constructor takes an options object with the following fields.

{Object} encoding - an Engram or plain object containing a Fields property with column definitions, optional.

{Boolean} bulkLoad - MSSQLJunction.store() and MSSQLWriter will use bulk load when possible, default is false.

{Object} auth - a plain object containing connection authentication information. See also auth_entries.json file.

{String} auth.username - username for the database connection.

{String} auth.password - password for the database connection.

Examples

Retrieve Rows

  const { Storage } = require("@dictadata/storage-junctions");
  const MSSQLJunction = require("../storage/junctions/mssql");

  function registerPlugins() {
    Storage.Junctions.use("mssql", MSSQLJunction);
  }

  async function retrieveData() {
    let rows;

    let smt = "mssql|server=dev.dictadata.net;database=storage_node|foo_schema|=Foo"
    let options = {
      username: "test",
      password: "test"
    }

    let pattern: {
      match: {
        "Foo": "first",
        "Baz": { "gte": 0, "lte": 1000 }
      },
      count: 3,
      order: { "Dt Test": "asc" },
      fields: [ "Foo", "Bar", "Baz" ]
    }

    var junction;
    try {
      junction = await Storage.activate(smt, options);
      let results = await junction.retrieve(pattern);

      console.log("result: " + results.status + " count: " + (results.data ? results.data.length : 0));
      console.log(JSON.stringify(results, null, "  "));

      rows = results.data;
    }
    catch (err) {
      console.error('!!! request failed: ' + err.status + " " + err.message);
      retCode = 1;
    }
    finally {
      if (junction)
        await junction.relax();
    }

    return rows;
  }

Streaming

The following example creates an instance of MSSQLReader and collects streamed data into an array. In this case the storage construct is an object representing a row of columns from the MSSQL table. MSSQLReader is derived from Node.js stream Readable. So the reader can be the source of any Node.js pipeline.

  const { Storage } = require("@dictadata/storage-junctions");
  const MSSQLJunction = require("../storage/junctions/mssql");

  function registerPlugins() {
    Storage.Junctions.use("mssql", MSSQLJunction);
  }

  async function retrieveData() {
    let response = [];

    let smt = "mssql|server=dev.dictadata.net;database=storage_node|foo_schema|=Foo"
    let options = {
      username: "test",
      password: "test"
    }

    let junction = Storage.activate(smt, options);
    let reader = junction.createReader();

    reader.on('data', (construct) => {
      response.push(construct);
    })
    rs.on('end', () => {
      console.log('End of data.');
    });
    rs.on('error', (err) => {
      console.error(err);
    });

    await stream.finished(reader);

    return response;
  }

Using MSSQLJunction plugin with Storage-Tracts (ETL)

MSSQLJunction can be used from the command line, batch file or task schedular via the Storage-Tracts ETL command line interface.

Install Storage-Tracts

Install Storage-Tracts in NPM's global workspace. This will allow you to run from any folder using the command "etl" or "storage-etl".

npm -g install @dictadata/storage-tracts

Storage_ETL CLI

The ETL app takes two parameters as shown below. See the Storage-Tracts documentation for full details.

etl [-t tractsFile] [tractName]

ETL Tracts File

An ETL Tracts file is a JSON object describing the storage source and storage destination. Each top level property is a tract. For MSSQL files you will need to also specify the plugin.

{
  "config": {
    "plugins": {
      "junctions": {
        "@dictadata/mssql-junction": [ "mssql" ]
      }
    }
  },
  "transfer": {
    "name": "foo_transfer",
    "action": "transfer",
    "origin": {
      "smt": "mssql|./test/data/input/|foofile.mssql|*",
      "options": {}
    },
    "terminal": {
      "smt": "json|./test/data/output/|foofile.json|*"
    }
  }
}