Abrufen von Daten aus vielen zu vielen Beziehung und zeigen in JSON wie Objekte

Question

Ich muss Daten aus einer Datenbank mit SQL abfragen, aber ehrlich gesagt bin ich wirklich schlecht mit SQL. Ich habe viele-zu-viele Beziehungen und das Ergebnis muss in JSON wie Objekte nicht kontinuierliche Daten sein. Diese JSON ist das Ergebnis, das ich will, wo tags, quickTags und relatedTo sind many-to-many-Beziehungen:

{ 
     "idResource": "34613b76-0116-11e6-8d21-32d288336560", 
     "title": "Prof. Soledad Rath", 
     "description": "Est qui iure sequi repellat rerum iste a. Animi dolorum necessitatibus et id assumenda dolores.", 
     "minimumAge": "2", 
     "maximumAge": "10", 
     "fileName": "fuga", 
     "extension": "susp", 
     "URL": "https://www.Harvey.com/quia-quia-consequuntur", 
     "createTime": "2016-04-12 20:22:36", 
     "productionKey": "20106", 
     "creatorUser": "Marlin Corkery", 
     "creationCountry": "San Marino", 
     "resourceType": "tempore", 
     "tags": [ 
     { 
      "name": "provident" 
     } 
     ], 
     "quickTags": [ 
     { 
      "name": "veritatis" 
     } 
     ], 
     "relatedTo": [ 
     { 
      "name": "Mr. Earl Cartwright" 
     } 
     ] 
    }, 

ich nur den SQL-Code aus den Tags Tabelle und Ressourcen-Tags Tabelle gehen geben

-- ---------------------------- 
-- Table structure for `CTL_Tags` 
-- ---------------------------- 
DROP TABLE IF EXISTS `CTL_Tags`; 

CREATE TABLE `CTL_Tags` 
(
    `idTag` varchar(40) NOT NULL COMMENT 'Primary key UUID format', 
    `name` varchar(45) NOT NULL COMMENT 'Name of the relationship,\nThis can be defined like:\n \nFather,\nMother,\nUncle,\nAunt,\nEtc.', 
    PRIMARY KEY (`idTag`) 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='This table contains a Catalog of Tags of the relationships '; 

-- ---------------------------- 
-- Table structure for `CTL_Resource_has_Tags` 
-- ---------------------------- 
DROP TABLE IF EXISTS `CTL_Resource_has_Tags`; 

CREATE TABLE `CTL_Resource_has_Tags` 
(
    `idResource` varchar(40) NOT NULL COMMENT 'Foreign key to the CTL_Resource table ', 
    `idTag` varchar(40) NOT NULL COMMENT 'foreign key to the CTL_Tags table.', 
    PRIMARY KEY (`idResource`,`idTag`), 
    KEY `fk_CTL_Resource_has_Tag_Tag1_idx` (`idTag`), 
    KEY `fk_CTL_Resource_has_Tag_CTL_Resource1_idx` (`idResource`), 
    CONSTRAINT `fk_CTL_Resource_has_Tag_CTL_Resource1_idx` FOREIGN KEY (`idResource`) REFERENCES `CTL_Resource` (`idResource`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_CTL_Resource_has_Tag_Tag1_idx` FOREIGN KEY (`idTag`) REFERENCES `CTL_Tags` (`idTag`) ON DELETE NO ACTION ON UPDATE NO ACTION 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='this table establishes the amount of tags that a given tag'; 

wo die CTL_Resources Tabelle

-- ---------------------------- 
-- Table structure for `CTL_Resource` 
-- ---------------------------- 
DROP TABLE IF EXISTS `CTL_Resource`; 

CREATE TABLE `CTL_Resource` 
(
    `idResource` varchar(40) NOT NULL DEFAULT '0' COMMENT 'Primary key UUID format', 
    `idResourceType` varchar(40) NOT NULL COMMENT 'foreign key pointing to the resource type', 
    `idCreatorUser` varchar(40) NOT NULL COMMENT 'Foreign key pointing to the user who created the resource\n', 
    `idModifierUser` varchar(40) NOT NULL COMMENT 'Foreign key pointing to the user who modified the resource\n', 
    `idCreationCountry` varchar(40) NOT NULL COMMENT 'foreign key pointing to the CTL_country table\n\nthis relationship shows the country from which the resource was created', 
    `title` varchar(45) DEFAULT NULL COMMENT 'Title of the resource', 
    `description` mediumtext CHARACTER SET big5 COMMENT 'Description of the resource', 
    `thumbnail` varchar(1024) DEFAULT NULL COMMENT 'url/path to the thumbnail representing this resource.', 
    `minimumAge` varchar(45) DEFAULT NULL COMMENT 'Minimum age required to assign this resource', 
    `maximumAge` varchar(45) DEFAULT NULL COMMENT 'Maximum age required to assign this resource', 
    `fileName` varchar(1024) DEFAULT NULL COMMENT 'url/path to the file related to this resource.', 
    `extension` varchar(45) DEFAULT NULL COMMENT 'extension of the resource', 
    `coachVisibility` varchar(3) DEFAULT NULL COMMENT 'Visibility status :\nVIS = visible\nINV = invisible\n', 
    `studentVisibility` varchar(3) DEFAULT NULL COMMENT 'Visibility status :\nVIS = visible\nINV = invisible\n', 
    `isHTML` varchar(4) DEFAULT NULL COMMENT 'If the resource is HTML this field should contain:\n\nHTML = this resource is HTML\n', 
    `studentIndex` varchar(45) DEFAULT NULL COMMENT 'If the resource is HTML and/or is of type TinCan this field should contain the starting page for the student user.', 
    `coachIndex` varchar(45) DEFAULT NULL COMMENT 'If the resource is HTML and/or is of type TinCan this field should contain the starting page for the coach user.', 
    `isURL` varchar(45) DEFAULT NULL COMMENT 'If the resource is URL this field should contain:\n\nURL = this resource is URL\n', 
    `URL` varchar(45) DEFAULT NULL COMMENT 'If the resource is URL this field should contain the URL of the resource.', 
    `source` varchar(45) DEFAULT NULL COMMENT 'It contains a description of where the resource was taken.', 
    `path` varchar(250) DEFAULT NULL COMMENT 'Path in which the resource is saved physically', 
    `status` varchar(3) NOT NULL DEFAULT 'ACT' COMMENT 'Code of status for internal control\nACT= Active\nINC = Inactive\nDEL = Deleted', 
    `createTime` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT 'Date and time when this record was inserted into the table', 
    `updateTime` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT 'Date and time of last update', 
    `isfolder` int(11) DEFAULT NULL, 
    `parentResource` varchar(40) DEFAULT NULL, 
    `productionKey` varchar(15) NOT NULL COMMENT 'production keys for resources', 
    PRIMARY KEY (`idResource`), 
    KEY `fk_CTL_Resource_CTL_ResourceType1_idx` (`idResourceType`), 
    KEY `fk_CTL_Resource_CTL_Country1_idx` (`idCreationCountry`), 
    KEY `fk_CTL_Resource_CTL_KnotionUser1_idx` (`idCreatorUser`), 
    KEY `fk_CTL_Resource_CTL_KnotionUser2_idx` (`idModifierUser`), 
    KEY `fk_parentResource_idx` (`parentResource`), 
    CONSTRAINT `fk_CTL_Resource_CTL_Country1` FOREIGN KEY (`idCreationCountry`) REFERENCES `CTL_Country` (`idCountry`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_CTL_Resource_CTL_KnotionUser1` FOREIGN KEY (`idCreatorUser`) REFERENCES `OPR_User` (`idUser`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_CTL_Resource_CTL_KnotionUser2` FOREIGN KEY (`idModifierUser`) REFERENCES `OPR_User` (`idUser`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_CTL_Resource_CTL_ResourceType1` FOREIGN KEY (`idResourceType`) REFERENCES `CTL_ResourceType` (`idResourceType`) ON DELETE NO ACTION ON UPDATE NO ACTION, 
    CONSTRAINT `fk_parentResource` FOREIGN KEY (`parentResource`) REFERENCES `CTL_Resource` (`idResource`) ON DELETE NO ACTION ON UPDATE NO ACTION 
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='Catalog of resources provided by the KnotionBank'; 

Nur für den Fall ist, ich arbeite mit ExpressJS mit keiner 01 in diesem Momentund mein Code ist dies ein

var query = `SELECT idResource, CTL_ResourceType.resourceType as resourceType, OPR_User.firstName as creatorUser, CTL_Country.country as creationCountry, title, description, CTL_Resource.thumbnail, minimumAge, maximumAge, fileName, extension, URL, source, path, productionKey 
       FROM CTL_Resource 
       LEFT JOIN CTL_ResourceType 
       ON CTL_Resource.idResourceType = CTL_ResourceType.idResourceType 
       LEFT JOIN OPR_User 
       ON CTL_Resource.idCreatorUser = OPR_User.idUser 
       LEFT JOIN CTL_Country 
       ON CTL_Resource.idCreationCountry = CTL_Country.idCountry` 


router.get('/', (req, res) => { 
    connection.query(query, (err, row, fields) => { 
    if (err) { 
     res.json(err) 
    } else { 
     res.json(row) 
    } 
    } 
)}) 

ich dankbar für jede Hilfe, die Sie gewähren können.

Answer 1

Wenn Sie SQL Server verwenden, können Sie die FOR XML-Syntax verwenden, mit der Sie ein XML-Objekt mit der gleichen Struktur wie das gewünschte Objekt zurückgeben können. Konvertieren Sie dann von XML zu JSON. Für andere Datenbanken gibt es einige Anschein von JSON/XML-Bibliotheken, aber ich habe festgestellt, dass sie für das, wonach Sie suchen, nicht besonders geeignet sind.

Wenn Sie SQL Server nicht verwenden, empfehle ich, eine Funktion zu erstellen, die Spalten mit eindeutigen Namen verwendet und auf eine Art von Objektdefinition verweist und das Objekt basierend auf den zurückgegebenen Ergebnissen erstellt.