@sap/xsodata/lib/serializer/metadataSerializer.js

Expose data from a HANA database as OData V2 service with help of .xsodata files.

'use strict';

var dbutils = require('./../utils/typeConverter');
var typConv = require('./../utils/typeConverter');
var XMLWriter = require('xml-writer');
var contentTypeTools = require('./../utils/checkContentType');
var associationsUtil = require('./../utils/associations');
var Measurement = require('./../utils/measurement');

function writeNavProperty(xw, navigation, associations, entityType, areAnnotationsEnabled) {

    xw.startElement('NavigationProperty');
    xw.writeAttribute('Name', navigation.name);
    var assocName = navigation.association;
    var association = associations[assocName];
    //
    xw.writeAttribute('Relationship', xw._ns + '.' + association.name + 'Type');

    xw.writeAttribute('FromRole', associationsUtil.createFromRoleString(navigation, association, entityType));
    xw.writeAttribute('ToRole', associationsUtil.createToRoleString(navigation, association, entityType));

	if (areAnnotationsEnabled) {
		writeAnnotationAttributes(entityType.getNavigationPropertyAnnotations(navigation.name), xw);
	}

    xw.endElement();
}

function writeProperty(xw, propertyName, col, entityType, areAnnotationsEnabled) {
    xw.startElement('Property');
    xw.writeAttribute('Name', propertyName);

	if (entityType.isConcurrentProperty(propertyName)) {
		xw.writeAttribute('ConcurrencyMode', 'Fixed');
	} 

    var oOataType = dbutils.dbTypeNameToODataTypeID(col.DATA_TYPE_NAME);
    xw.writeAttribute('Type', typConv.oDataTypeIDs[oOataType]);
    if (col.IS_NULLABLE !== 'TRUE') {
        xw.writeAttribute('Nullable', 'false');
    }

    if (oOataType === 9) { //String
        xw.writeAttribute('MaxLength', col.LENGTH);
    } else if (oOataType === 6) { //Decimal
        xw.writeAttribute('Precision', col.LENGTH);
        xw.writeAttribute('Scale', col.SCALE);
    }

	if (areAnnotationsEnabled) {
		writeAnnotationAttributes(entityType.getPropertyAnnotations(propertyName), xw);
	}

    xw.endElement();
}
function writeAssociationTypes(xw, associations) {
    // Associations
    for (var assocName in associations) {

        if (associations.hasOwnProperty(assocName)) {
            var assoc = associations[assocName];
            xw.startElement('Association');
            xw.writeAttribute('Name', assocName + 'Type');

            xw.startElement('End');
            xw.writeAttribute('Type', xw._ns + '.' + assoc.principal.type + 'Type');
            xw.writeAttribute('Role', assoc.principal.type + 'Principal');
            xw.writeAttribute('Multiplicity', assoc.principal.multiplicity);
            xw.endElement();

            xw.startElement('End');
            xw.writeAttribute('Type', xw._ns + '.' + assoc.dependent.type + 'Type');
            xw.writeAttribute('Role', assoc.dependent.type + 'Dependent');
            xw.writeAttribute('Multiplicity', assoc.dependent.multiplicity);
            xw.endElement();

            if (assoc.referentialConstraint){
                xw.startElement('ReferentialConstraint');

                xw.startElement('Principal');
                xw.writeAttribute('Role', assoc.principal.type + 'Principal');
                xw.startElement('PropertyRef');
                xw.writeAttribute('Name', assoc.principal.joinproperties[0]);
                xw.endElement();
                xw.endElement();//Principal

                xw.startElement('Dependent');
                xw.writeAttribute('Role', assoc.dependent.type + 'Dependent');
                xw.startElement('PropertyRef');
                xw.writeAttribute('Name', assoc.dependent.joinproperties[0]);
                xw.endElement();
                xw.endElement();//Dependent

                xw.endElement();//ReferentialConstraint
            }

            xw.endElement();//Association
        }
    }
}


function writeEntityTypes(xw, entityTypes, associations, areAnnotationsEnabled) {
    var i, ii, j;

    /**
     * @type {EntityType}
     * */
    var entityType = null;

    for (i = 0; i < entityTypes.length; i++) {
        entityType = entityTypes[i];

        xw.startElement('EntityType');
        xw.writeAttribute('Name', entityType.name + 'Type');

	    if (areAnnotationsEnabled) {
		    writeAnnotationAttributes(entityType.getEntityTypeAnnotations(), xw);
	    }

        //keys

        xw.startElement('Key');

        entityType.getKeysOrGenKey().forEach(writeKey);
        xw.endElement();

        var props = entityType.getPropertiesWithGenKey();
        for (j = 0; j < props.length; j++) {
            writeProp(props[j], entityType);
        }

        //nav properties
        for (ii = 0; ii < entityType.navProperties.length; ii++) {
            var navigation = entityType.navProperties[ii];
            writeNavProperty(xw, navigation, associations, entityType, areAnnotationsEnabled);
        }
        xw.endElement();
    }

    function writeKey(keyName) {
        xw.startElement('PropertyRef');
        xw.writeAttribute('Name', keyName);
        xw.endElement();
    }

    function writeProp(property, entityType) {
        writeProperty(xw, property.COLUMN_NAME, property, entityType, areAnnotationsEnabled);
    }
}

function writeEntitySets(xw, entityTypes, areAnnotationsEnabled) {
    for (var i = 0; i < entityTypes.length; i++) {
        var entityType = entityTypes[i];
        xw.startElement('EntitySet');
        xw.writeAttribute('Name', entityType.name);
        xw.writeAttribute('EntityType', xw._ns + '.' + entityType.name + 'Type');

	    if (areAnnotationsEnabled) {
		    writeAnnotationAttributes(entityType.getEntitySetAnnotations(), xw);
	    }

        xw.endElement();
    }
}

function writeAssociations(xw, associations, areAnnotationsEnabled) {
    for (var i = 0; i < associations.length; i++) {

        var assocication = associations[i];
        xw.startElement('AssociationSet');
        xw.writeAttribute('Name', assocication.name);
        xw.writeAttribute('Association', xw._ns + '.' + assocication.name + 'Type');

	    if (areAnnotationsEnabled) {
		    writeAnnotationAttributes(assocication.getAssociationSetAnnotations(), xw);
	    }

        xw.startElement('End');
        xw.writeAttribute('Role', assocication.principal.type + 'Principal');
        xw.writeAttribute('EntitySet', assocication.principal.type);
        xw.endElement();

        xw.startElement('End');
        xw.writeAttribute('Role', assocication.dependent.type + 'Dependent');
        xw.writeAttribute('EntitySet', assocication.dependent.type);
        xw.endElement();

        xw.endElement();//AssociationSet

    }
}

exports.process = function (context, asyncDone) {
	var response = context.response,
		format = context.oData.systemQueryParameters.format,
		areAnnotationsEnabled = context.gModel.areAnnotationsEnabled();

	context.logger.silly('metadataprocessor', 'process');
    context.payloadType = Measurement.measureSync(contentTypeTools.checkServiceMetadata, context.request, format, 'contentTypeTools.checkServiceMetadata');

    var header = {
        'Content-Type': context.payloadType + ';charset=utf-8'
    };

    var cacheControl = context.gModel.getSetting('metadata','cache-control');
    if (cacheControl) {
        header['cache-control'] = cacheControl;
    }

    response.writeHead(200, header);

    var writer = function writer(string) {
        response.write(string);
    };

    var xw = new XMLWriter(true, writer);//change to false for unformatted output

    //xsodata.scenario
    xw._ns = context.gModel.getNamespace();
    xw.startDocument('1.0', 'utf-8', true);

    xw.startElement('edmx:Edmx');
    xw.writeAttribute('Version', '1.0');
    xw.writeAttribute('xmlns:edmx', 'http://schemas.microsoft.com/ado/2007/06/edmx');

	if (areAnnotationsEnabled) {
		xw.writeAttribute('xmlns:sap', 'http://www.sap.com/Protocols/SAPData');
	}

    xw.startElement('edmx:DataServices');
    xw.writeAttribute('m:DataServiceVersion', '2.0');
    xw.writeAttribute('xmlns:m', 'http://schemas.microsoft.com/ado/2007/08/dataservices/metadata');

    xw.startElement('Schema');
    xw.writeAttribute('Namespace', xw._ns);
    xw.writeAttribute('xmlns:d', 'http://schemas.microsoft.com/ado/2007/08/dataservices');
    xw.writeAttribute('xmlns:m', 'http://schemas.microsoft.com/ado/2007/08/dataservices/metadata');
    xw.writeAttribute('xmlns', 'http://schemas.microsoft.com/ado/2008/09/edm');

    var entityTypes = context.gModel.getEntityTypes();
    var associations = context.gModel.getAssociationsMap();
    Measurement.measureSync(writeEntityTypes, xw, entityTypes, associations, areAnnotationsEnabled, 'writeEntityTypes');
    Measurement.measureSync(writeAssociationTypes, xw, associations, 'writeAssociationTypes');

    //Entity Container
    xw.startElement('EntityContainer');
    xw.writeAttribute('Name', 'v2');
    xw.writeAttribute('m:IsDefaultEntityContainer', 'true');

    writeEntitySets(xw, entityTypes, areAnnotationsEnabled);
    writeAssociations(xw, context.gModel.getAssociations(), areAnnotationsEnabled);
    xw.endElement();//EntityContainer

    xw.endDocument();
    response.write(xw.toString());

    return asyncDone(null, context);
};

exports._writeAnnotationAttributes = writeAnnotationAttributes;

/**
 * Writes CSDL annotation attributes to the current EDM element.
 *
 * @param {Object} annotations - object with the properties representing the annotation attributes
 * @param {Object} xmlWriter - XMLWriter instance, which is used for the metadata serialization
 */
function writeAnnotationAttributes(annotations, xmlWriter) {
	var annotation;

	if (!annotations) {
		return;
	}

	for (annotation in annotations) {
		if (annotations.hasOwnProperty(annotation)) {
			xmlWriter.writeAttribute(annotation, annotations[annotation]);
		}
	}
}

exports.writeEntityTypes = writeEntityTypes;