@sap/hdbext

This package provides convenient functions on top of the @sap/hana-client module.

The change log describes notable changes in this package.

Usage

var hdbext = require('@sap/hdbext');

API

createConnection(hanaConfig, callback)

Creates a connection to a HANA database:

var hanaConfig = {
  host     : 'hostname',
  port     : 30015,
  user     : 'user',
  password : 'secret'
};
hdbext.createConnection(hanaConfig, function(error, client) {
  if (error) {
    return console.error(error);
  }

  client.exec(...);
});

The hanaConfig argument contains database connection options and additional options. The callback provides a connected client object.

If the application will be deployed on Cloud Foundry or XS Advanced, you can use @sap/xsenv package to lookup the bound HANA service, like this:

var xsenv = require('@sap/xsenv');

var hanaConfig = xsenv.cfServiceCredentials({ tag: 'hana' });
hdbext.createConnection(hanaConfig, function(error, client) {
  //...
});

Database connection options

The HANA options provided to @sap/hdbext should be in the same format as expected by the @sap/hana-client package.

For convenience these properties set by the HANA service broker are also accepted:

schema - can be used instead of the currentSchema property of @sap/hana-client.
db_hosts - can be used instead of the hosts property of @sap/hana-client.
certificate - can be used instead of ca property of @sap/hana-client. Note: certificate is a string containing one certificate, while ca is an array of certificates.
hostname_in_certificate - can be used instead of sslHostNameInCertificate property of @sap/hana-client.
validate_certificate - can be used instead of sslValidateCertificate property of @sap/hana-client. The default value is true.
client_authentication_certificate - can be used instead of cert property of @sap/hana-client.
client_authentication_private_key - can be used instead of key property of @sap/hana-client.

Additional options

A connection created with @sap/hdbext can be further configured with the following options:

Option	Type	Description
`autoCommit`	boolean	Sets the autoCommit flag. If no option is specified it defaults to `true`.

Note: the @sap/hana-client package also accepts other configurations like isolationLevel (one can use the isolation level constants in require('@sap/hana-client/extension/Enums')), locale and sessionVariable:<name-of-the-session-variable>.

Special session variables

Some session variables are handled in a special way.

XS_APPLICATIONUSER - can be set to a user token (SAML/JWT) to associate the application user with the database connection
SAP_PASSPORT - used to propagate SAP passport to SAP HANA, used for end-to-end tracing
APPLICATION - the name of the application initiating the database connection

Note: If providing the SAP_PASSPORT session variable, the SAP Passport in it should have already been updated with data, specific to the component that consumes @sap/hdbext. For more information, see the documentation of the @sap/e2e-trace package.

Example

Sample configuration with both database connection options and additional options:

var enums = require('@sap/hana-client/extension/Enums');

{
  host: 'my.host',
  port: 30015,
  user: 'my_user',
  password: 'secret',
  schema: 'name_of_the_schema',
  isolationLevel: enums.SERIALIZABLE,
  locale: 'en_US',
  autoCommit: false,
  'sessionVariable:APPLICATION': 'myapp',
  'sessionVariable:SAP_PASSPORT': 'passport'
}

connectionOptions.getGlobalOptions()

Returns an object with the following properties:

sessionVariable:APPLICATION - extracted from VCAP_APPLICATION, fallbacks to process's pid and machine's hostname.
sessionVariable:APPLICATIONVERSION - extracted from package.json in current directory. May not be present if the file is not present or not in valid JSON format.

connectionOptions.getRequestOptions(req)

Returns an object with the following properties, based on the given HTTP request (req):

sessionVariable:SAP_PASSPORT - may not be present if the SAP Passport header is not present. The passport is updated with default component data.
sessionVariable:XS_APPLICATIONUSER - only present for authenticated requests that do not use client credentials token.
locale - only present if req has either a x-sap-request-language or accept-language header.

loadProcedure(client, schemaName, procedureName, callback)

@sap/hdbext provides functionalities to simplify stored procedure calls.

For example, if you have the following stored procedure:

create procedure PROC_DUMMY (in a int, in b int, out c int, out d DUMMY, out e TABLES)
  language sqlscript
  reads sql data as
  begin
    c := :a + :b;
    d = select * from DUMMY;
    e = select TOP 3 * from TABLES;
  end

you can call it via the @sap/hana-client package in the following way:

var dbStream = require('@sap/hana-client/extension/Stream');
dbStream.createProcStatement(client, 'CALL PROC_DUMMY (?, ?, ?, ?, ?)', function (err, stmt) {
  if (err) {
    return console.error('createProcStatement error:', err);
  }

  stmt.exec({ A: 3, B: 4 }, function (err, params, dummyRows, tablesRows) {
    if (err) {
      return console.error('exec error:', err);
    }

    stmt.drop(function (err) {
      if (err) {
        return console.error('drop error:', err);
      }

      console.log('C:', params.C);
      console.log('Dummy rows:', dummyRows);
      console.log('Tables rows:', tablesRows);
    });
  });
});

With @sap/hdbext you don't need to construct a CALL statement. The procedure can be loaded by its name. The code can look like this:

hdbext.loadProcedure(client, null, 'PROC_DUMMY', function(err, sp) {
  sp({ A: 3, B: 4 }, function(err, parameters, dummyRows, tablesRows) {
    if (err) {
      return console.error(err);
    }

    console.log('C:', parameters.C);
    console.log('Dummy rows:', dummyRows);
    console.log('Tables rows:', tablesRows);
  });
});

To use the current schema, pass an empty string '', null or undefined for schema.

loadProcedure(client, schemaName, procedureName, callback) returns a JavaScript function which you can call directly. The function has the paramsMetadata property containing metadata for all parameters of the stored procedure. This could be useful if you need to implement generic stored procedures calling.

You can also pass the input parameters directly in the proper order:

sp(3, 4, function(err, parameters, dummyRows, tableRows) {
  // ...
});

or as an array:

sp([3, 4], function(err, parameters, dummyRows, tableRows) {
  // ...
});

Where the big advantage comes in is with table parameters. You can pass an array of objects and @sap/hdbext will automatically convert it into a table parameter. Say we have a customer table with ID and NAME columns and a procedure:

create table "customer" (ID integer, NAME VARCHAR(100), primary key (ID));

create procedure "getCustomers" (in in_table_1 "customer")
language sqlscript reads sql data as begin
select * from :in_table_1;
end;

You can call it like this:

hdbext.loadProcedure(client, null, 'getCustomers', function (err, sp) {
  if (err) {
    return console.error(err);
  }

  sp([
    { ID: 1, NAME: 'Alex' },
    { ID: 2, NAME: 'Peter' }
  ], function (err, parameters, tableRows) {
    if (err) {
      return console.error(err);
    }

    console.log(parameters);
    console.log(tableRows);
  });
});

In this example each array element represents a table row. Property names should case-sensitively match the corresponding column names.

Internally @sap/hdbext creates a local temporary table in the current schema for each table parameter. Thus, the current user needs the respective permissions.

It is also possible to explicitly state an existing table to be used as input table parameter:

  sp({ schema: 'my-schema', table: 'my-table' }, function (err, parameters, tableRows) {
    // ...
  });

The schema property is optional.

Every output table has a columnInfo property which contains info about each of the table's columns.

Input arguments for parameters that have default values can be skipped in order to use the defined defaults. It is recommended to pass the input as an object in those cases. In this way the application code would be independent from the order in which parameters with default values are defined in the procedure. When the parameters are passed in a sequence (i.e. as an array or are passed directly in the proper order), input arguments can be skipped only for the parameters which are after the last mandatory parameter in the procedure's list.

Middleware

@sap/hdbext provides a middleware which allows easy database connection creation in a middleware-based application. The close method of the database client is invoked when the request is closed or finished.

var hdbext = require('@sap/hdbext');
var express = require('express');

var app = express();
app.use(hdbext.middleware(hanaConfig));

app.get('/execute-query', function (req, res) {
  var client = req.db;

  client.exec('SELECT * FROM DUMMY', function (err, rs) {
    if (err) {
      return res.end('Error: ' + err.message);
    }

    res.end(JSON.stringify(rs));
  });
});

The argument hanaConfig may contain both database connection options and additional options.

The middleware uses connectionOptions.getGlobalOptions() and connectionOptions.getRequestOptions(req) for extracting options. It is possible for applications to override the default global options by setting them explicitly in hanaConfig.

SQL Parameter Utilities

The hdbext.sqlInjectionUtils object contains several synchronous utility functions that can be used to prevent SQL injections.

isAcceptableParameter(value, maxToken)

Returns true if value can be used to construct SQL statements. The number of tokens a value is allowed to contain is set via the optional maxToken argument. Defaults to 1.

isAcceptableQuotedParameter(value)

Returns true if the provided value is quoted correctly and can be used in an SQL statement.

escapeDoubleQuotes(value)

Returns the value parameter with all double quotation marks escaped (i. e. doubled).

escapeSingleQuotes(value)

Returns the value parameter with all single quotation marks escaped (i. e. doubled).

Troubleshooting

To enable tracing, you should set the environment variable DEBUG to hdbext:*.