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Configure the Backend Input Forms

In our sample application the data of our extension should be editable in the Backend by the editors of the youth club organisation and - within certain limitations - in the Frontend as well providing functionalities for creation, update and deletion of the organisation's data. In this chapter we firstly configure the Backend's form inputs for easy access to the database's contents. The forms providing the management functionalities are stored in a certain PHP-Array called Table Configuration Array (TCA). The TCA is stored in a file with the database table name suffixed with .php in the directory Configuration/TCA/ Example: The TCA for the database table tx_sjroffers_domain_model_organization is therefore in the file Configuration/TCA/tx_sjroffers_domain_model_organization.php.

Note

The configuration options that can be set in the TCA are very extensive and a broad description of them would cause the book being bursting at its seams. However, each and every option is well documented in the Online-documentation TCA Reference

Firstly, you should dip into the top layer of the TCA hierarchy. The TCA for table tx_sjroffers_domain_model_organization is in the file Configuration/TCA/tx_sjroffers_domain_model_organization.php and has this structure:

<?php
return [
    'ctrl' => [
        // …
    ],
    'columns' => [
        // …
    ],
    'types' => [
        // …
    ],
];

The structure for the other tables like tx_sjroffers_domain_model_offer and tx_sjroffers_domain_model_person are equal.

These returned arrays in these files will be added to one big array $GLOBALS['TCA']. You can debug the configuration for the table tx_sjroffers_domain_model_organization in the TYPO3 backend module System -> Configuration -> $GLOBALS['TCA'] (Table configuration array) -> tx_sjroffers_domain_model_organization

The associative array, that is returned, contains all information of all the tables of the TYPO3 instance. Thus, we use the key tx_sjroffers_domain_model_organization and as value we use another nested Array holding the configurations of the corresponding table. Then again, this Array is separated into several parts whose names are the key of the nested Array.

<?php
return [
   'ctrl' => [
      // …
   ],
   'interface' => [
      // …
   ],
   'types' => [
      // …
   ]
   'palettes' => [
      // …
   ],
   'columns' => [
      'first_fieldname' => [
         // …
      ],
      'second_fieldname' => [
         // …
      ],
   ],
];

Subsequently, you will find the names of the parts and their meaning.

ctrl This area contains configuration options that are used overall the scope of the table. This covers the naming of the table in the Backend, which table fields contain which meta data and the behavior of the table on creation and movement of its row sets. Meta data cover information about Visibility and Access Control (e.g. disabled, hidden, starttime, endtime, fe_group), data about the history of changes (e.g. versioningWS, crdate, tstamp as well as data for the localization of data sets (e.g. languageField).

interface This part contains information about the representation of the table data in the Backend's List Module. The key showRecordFieldList contains a comma-separated list of field values whose values will be shown in the info dialogue of the table. This dialogue may be reached through a right-click on the icon of the row set choosing the Info option. Altering the option maxDBListItems you can set how many row sets will be shown in the List Module without switching to the detail view of the database table. Then again, the number of row sets shown on a page in this perspective may be set via maxSingleDBListItems. Setting the option always_description to true the corresponding helping texts always show up.

types This section defines the appearance of the Input Form for creation and update of a row set. You can define several layout types by listing several elements in the array types. The key of all those elements is their type (usually a number) and their value is another nested array which itself usually contains one element with showItem as key and a list of comma-separated field names which should emerge at the Input Form. An example of the table tx_sjroffers_domain_model_organization is:

'types' => [
   '0' => ['showitem' => 'hidden,status,name,address;;1;;description,contacts,offers,administrator'],
],

Even though the behavior and the appearance of the table fields is configured in the section columns they must be explicitly listed in here so that they show up in the input form. This spares the trouble you would have when commenting out or moving away code that is already configured and a corresponding field should just be hidden or the overall order of the Input Form's table fields should be changed.

The behaviour and the appearance of a field may be altered through several additional parameters - as well as with the field address. The notion convention of those additional params may seem a bit unfamiliar since they are appended behind the fieldname and separated through a semi-colon. On first position there is the fieldname; on the second an alternative naming fieldname; at third place follows the number of the palette (refer to the next book section); the fourth position holds extensive options which are separated through colons and the last place contains information about the appearance (e.g. color and structure). The information at the fourth place allow the use of the Rich Text Editor. For a full list of the options refer to the already mentioned TYPO3-Online documentation for the TYPO3-Core API.

palettes Palettes are used to collect occasionally used fields and show them up on demand. The Backend user therefore has to choose the Extended View in the Backend's List module. Palettes are connected to a durable visible field. An example from the table tx_sjroffers_domain_model_organization is:

'palettes' => [
   '1' => ['showitem' => 'telephone_number,telefax_number,url,email_address'],
],

The structure is the same as in the section types where address;;1;; refers to the palette with the number 1.

columns This Array contains information about the behavior and the appearance in the Input Form of every table field. The fieldname is the key and, again, the value is a nested array holding the field's corresponding configuration. The field configuration for the input of the name of an organisation would be as follows:

'name' => [
   'exclude' => false,
   'label' => 'LLL:EXT:sjr_offers/Resources/Private/Language/locallang_db.xml:tx_sjroffers_domain_model_organization.name',
   'config' => [
      'type' => 'input',
      'size' => 20,
      'eval' => 'trim,required',
      'max' => 256
   ],
],

The field name is name. Firstly, we define some options that are independent from the field's type. This contains foremostly the field label (label), the conditions for the visibility of the field (exclude, displayCond) as well as information for its localization (l10n_mode, l10n_cat). The fieldname is, in our case, localized and will be taken from a language file (head to Ch. 9).

The array connected to config contains the field type and its corresponding configuration. TYPO3 serves with a great range of pre-defined field types, e.g. text fields, date fields or selection fields. Each and every type has its own presentation and procession options. Consecutively, you will find a list of all the field types with their usual configurations:

Field type "input"

The input field type accepts one-line character strings like names and telephone numbers. The configuration of a name field (see Fig. 6-1) looks as follows:

'name' => [
   'label' => 'Organization's name',
   'config' => [
      'type' => 'input',
      'size' => 20,
      'eval' => 'trim,required',
      'max' => 256
   ],
],

The given string will be truncated to 256 signs ('max' => 256), ending spaces will be dropped (trim) and the persistence of an empty field will be prevented (required).

Note

Important: When a field is defined as required, the Domain Model must have the annotation @NotEmpty for the validator.

Figure 6-1: An example for the field type "input" used as a name field.

The field type input may be used for date and time inputs:

'minimum_value' => [
   'label' => 'valid since',
   'config' => [
      'type' => 'input',
      'size' => 8,
      'checkbox' => '',
      'eval' => 'date'
   ],
],

The value then will be tested for being given in a sane date format. Simultaneously, this leads to the rendering of a collapsable calendar page in shape of an icon right to the input field which is shown in Fig. 6-2:

Figure 6-2: An example for the field type "input" used as a date field.

Field type "text"

The text field type may contain multi-line formatted or unformatted texts e.g. product descriptions, addresses or news items. The indication of the lines (rows) and the columns (cols) specifies the area of the text input field.

'address' => [
   'label' => 'Address:',
   'config' => [
      'type' => 'text',
      'cols' => 20,
      'rows' => 3
   ],
],

Figure 6-3: An example for the field type "text".

Field type "check"

The field type check allows the definition of a single option (see Fig. 6-4)

e.g. you can define whether a rowset should be hidden or not.

'hidden' => [
   'label' => 'Hide:',
   'config' => [
      'type' => 'check'
   ],
],

Figure 6-4: An example for the field type "check" for a single option.

Several related options which can be individually selected can be grouped to a field (see Fig. 6-5). This may be helpful e.g. for a selection of valid weekdays or recommended training levels of a certain exercise.

'level' => [
   'exclude' => true,
   'label' => 'Property for',
   'config' => [
      'type' => 'check',
      'eval' => 'required,unique',
      'cols' => 5,
      'default' => 31,
      'items' => [
         ['Level 1',''],
         ['Level 2',''],
         ['Level 3',''],
         ['Level 4',''],
         ['Level 5',''],
      ],
   ],
],

<!-- TODO: look, how math is being processed for the coming exp-value --> The value that is written to the database is of type Integer. This will be computed by bitwise addition of the checkboxes states (which can be 1 or 0). The first element (Level 1) is the least significant Bit (= 2^0 = 1). The second element is one level above (= 2^1 = 2), the third element will then be (= 2^2 = 4) etc. The selection in the following Figure (see Fig. 6-5) would lead to the following Bit-Pattern (= binary-written number): 00101. This binary number is equivalent to the Integer value 5.

Figure 6-5: An example for the field type "check" for several options that are grouped together.

Field type "radio"

The field type radio is for choosing one unique value for a given property (see Fig. 6-6), e.g. the sex of a person or the color of a product.

'gender' => [
   'label' => 'Sex',
   'config' => [
      'type' => 'radio',
      'default' => 'm',
      'items' => [
         ['male', 'm'],
         ['female', 'f'],
      ],
   ],
],

The options (items) are given in an array and each option is an array itself containing the label and the key used for persist the selected option in the database.

Figure 6-6: An example for the field type "radio".

Field type "select"

The field type "select" provides a space-saving way to render multiple values (see Fig. 6-7). Examples could be a member status, a product color or a region.

'status' => [
   'exclude' => false,
   'label' => 'Status',
   'config' => [
      'type' => 'select',
      'foreign_table' => 'tx_sjroffers_domain_model_status',
      'maxitems' => 1
   ],
],

The options are taken from another database table (foreign_table) and by setting maxitems to 1 (which is standard) the selection box will be limited to exactly one showed item.

Figure 6-7: An example for the field type "select" showing a selection box.

The type select may also be used to select a whole subset of values. This is used for categories, tags or contact persons (see Fig. 6-8).

'categories' => [
   'exclude' => true,
   'label' => 'Categories',
   'config' => [
      'type' => 'select',
      'size' => 10,
      'minitems' => 0,
      'maxitems' => 9999,
      'autoSizeMax' => 5,
      'multiple' => 0,
      'foreign_table' => 'tx_sjroffers_domain_model_category',
      'MM' => 'tx_sjroffers_offer_category_mm'
   ],
],

Again, this takes the options of another table but it holds the references in a temporary table tx_sjroffers_offer_category_mm.

Figure 6-8: An example for the field type "select".

Field type "group"

The "group" field type is very flexible in its use. It can be used to manage references to resources to the filesystem or rowsets of a database (see Fig. 6-9).

'images' => [
   'label' => 'Images',
   'config' => [
      'type' => 'group',
      'internal_type' => 'file',
      'allowed' => 'gif,jpg',
      'max_size' => 1000,
      'uploadfolder' => 'uploads/pics/',
      'show_thumbs' => 1,
      'size' => 3,
      'minitems' => 0,
      'maxitems' => 200,
      'autoSizeMax' => 10
   ],
],

The combination of type and internal_type specifies the field's type. Besides of file there exist several other types like file_reference, folder and db. While file leads to a copy of the original file which is then being referenced the type file_reference leads to a direct reference to the original file. db leads to a direct reference to a database rowset.

Note

Extbase currently does not resolve relations to other rowsets since the relations are currently persisted as comma-separated values in the database field (pic1.jpg,pic2.jpg,pic3.jpg). However, this can be resolved in a ViewHelper in Fluid when the data shows up (see the entry f:image in Appendix C)

Figure 6-9: An example for the field type "group".

Field type "none"

Fields of this type show up the raw data values which cannot be edited (see Fig. 6-10).

'date' => [
   'label' => 'Datum (Timestamp)',
   'config' => [
      'type' => 'none'
   ],
],

In contrast to the date field with the type input there is no evaluation as with 'eval' => 'date'. The timestamp which is set in the database will be shown as a raw number.

Figure 6-10: An example for the field type "none" for a date field.

Field type "passthrough"

The field type "passthrough" is for data which are processed internally but cannot be edited or viewed in the form. An example for that would be information to references (foreign keys).

'organization' => [
   'config' => [
      'type' => 'passthrough'
   ],
],

This field configuration in the database table tx_sjroffers_domain_model_offer has the effect that the property organization of the Offer-object will be filled with the correct object.

Field type "user"

User generates free definable form fields which can be processed by any PHP function. For further information, refer to the documentation which is available online and to the TYPO3-Code API.

Field type "flex"

The field type "flex" manages complex inline form fields (FlexForms). The form data will be saved as XML data structure in the database fields. Extbase uses FlexForms for persisting plugin configuration but not to save domain data. If your plugin data will be rather complex we encourage you to design an own backend module for them (refer to Ch. 10).

Field type "inline"

The field type "inline" is for saving complex Aggregates of the Domain (see Fig. 6-11). Basis of this field type is the so called Inline Relational Record Editing (IRRE) which powers the creation, update and deletion of Domain-objects of whole Aggregates in a single Input Form. Without IRRE the Domain-objects must be edited and connected each by itself which would require an intermediate save. This technique is a comfortable tool for managing complex Aggregates. All the possibilities provided by IRRE are well documented, refer to the TYPO3 TCA Reference.

'offers' => [
   'label' => 'Offers',
   'config' => [
      'type' => 'inline',
      'foreign_table' => 'tx_sjroffers_domain_model_offer',
      'foreign_field' => 'organization',
      'maxitems' => 9999
   ],
],

The configuration is almost identical to the field type "select". However, there are several more possibilities for the configuration of the management and the representation of the connected objects.

Figure 6-11: An example for the field type "irre".

Extbase supports the most important aspects of IRRE with only one exception: IRRE allows a temporary table of an m:n-relationship to be enhanced by additional fields which can hold Domain data. An example: Assume that we want to connect a CD to it's containing music tracks, whereas a CD can contain multiple tracks and one track can be present on several CD's. Thus, we can derive the following temporary table:

CD --1:n-- Temporary-Table --n:1-- Title

The corresponding IRRE-Configuration looks as follows:

'titles' => [
   'label' => 'Track Title',
   'config' => [
      'type' => 'inline',
      'foreign_table' => 'tx_myext_cd_title_mm',
      'foreign_field' => 'uid_local',
      'foreign_selector' => 'uid_foreign'
   ],
],

The IRRE-Tutorial describes this configuration as "state-of-the-art" for m:n-relationships. The option foreign_selector leads to a selection box for the music titles. Currently, IRRE only supports this option for m:n-relationships.

Every music track on the CD is given a unique track number. However, the track number is a neither a property of the CD nor that of a track. It's semantically corresponding to the relationship between them. Thus, IRRE provides the option to persist them within the temporary table and this can always be modelled into the Domain model which gets the following structure: CD --1:n-- Track --n:1-- Title.

Let's change the configuration of the table tx_myext_domain_model_track to a simple 1:n-relationship with cd as a foreign key.

'tracks' => [
   'label' => 'Track',
   'config' => [
      'type' => 'inline',
      'foreign_table' => 'tx_myext_domain_model_track',
      'foreign_field' => 'cd'
   ],
],

However, Extbase does not support the persistence of additional Domain data in the temporary table because the corresponding Domain object does not exist. Nevertheless, the Online documentation of the TYPO3-Core API describes the second, more correct option for configuring m:n-relationships within IRRE. It depends on a plain temporary table. The following example shows off the configuration of products with their according categories:

'categories' => [
   'label' => 'Categories',
   'config' => [
      'type' => 'inline',
      'foreign_table' => 'tx_myext_domain_model_category',
      'MM' => 'tx_myext_product_category_mm'
   ],
],

This second option deserves some additional kudos because it does not need a TCA-configuration for the temporary table tx_myext_product_category_mm because you don't need to show up or edit the whole table or parts of it in the Backend; the SQL definition is sufficiently.

Those are the summarized configuration possibilities within the TCA. As you see, the huge count of options can be overwhelming for the novice. But in future, they can be auto-generated by the Extension Builder (refer to Ch. 10).

As already mentioned, the TCA is stored in a file with the database table name as filename suffixed with .php in the directory Configuration/TCA/Overrides

tx_sjroffers_domain_model_organization.php

<?php
return [
   'ctrl' => [
      'title' => 'LLL:EXT:sjr_offers/Resources/Private/Language/locallang_db.xlf:tx_sjroffers_domain_model_organization',
      'label' => 'name',
      'tstamp' => 'tstamp',
      'crdate' => 'crdate',
      'languageField' => 'sys_language_uid',
      'transOrigPointerField' => 'l18n_parent',
      'transOrigDiffSourceField'  => 'l18n_diffsource',
      'prependAtCopy' => 'LLL:EXT:lang/locallang_general.xlf:LGL.prependAtCopy',
      'copyAfterDuplFields' => 'sys_language_uid',
      'useColumnsForDefaultValues' => 'sys_language_uid',
      'delete' => 'deleted',
      'enablecolumns' => [
         'disabled' => 'hidden'
      ],
      'iconfile' => 'EXT:sj_roffers/Resources/Public/Icons/Icon_tx_sjroffers_domain_model_organization.svg'
   ],
   'interface' => [
      'showRecordFieldList' => 'status,name,address,telephone_number,telefax_number,url,email_address,description,contacts,offers,administrator'
   ],
   'types' => [
      '0' => ['hidden,status,name,address;;1;;,description, contacts,offers,administrator']
   ],
   'palettes' => [
      '1' => ['showitem' => 'telephone_number,telefax_number,url,email_address']
   ],
   'columns' => [
      'sys_language_uid' => […],
      'l18n_parent' => […],
      'l18n_diffsource' => […],
      'hidden' => […],
      'status' => […],
      'name' => […],
      'address' => […],
      'telephone_number' => […],
      'telefax_number' => […],
      'url' => […],
      'email_address' => […],
      'description' => […],
      'contacts' => […],
      'offers' => […],
      'administrator' => […],
   ],
];

The tables of all the Domain objects are defined like this.

Now we can create a directory (SysDirectory) which will contain all the data sets. Let's create our first organization (see Fig. 6-12).

Figure 6-12: The input form for creating an organization with all its offers.

Now you can set up the whole data structure. In our project this allows the offer-provider to set up some example data and thus we could do some early integration tests. However, we can not access the given data because we still miss the Repositories that will be defined in the following section.

Creating the Repositories

We have already introduced the Repositories in Chapter 3. They serve with capabilities to save and reaccess our objects. We set up such a Repository object for every Aggregate-Root object which are, then again, used for accessing all the Aggregate-Root's corresponding objects. In our concrete example \MyVendor\SjrOffers\Domain\Model\Organization is such an Aggregate-Root object. The Repository's class name is derived from the class name of the Aggregate-Root object concatenated with the suffix Repository. The Repository needs to extend the class \TYPO3\CMS\Extbase\Persistence\Repository. The class file \MyVendor\ SjrOffers\Domain\Repository\OrganizationRepository will be saved in the directory EXT:sjr_ offers/Classes/Domain/Repository/. Thus the directory Repository is on the same hierarchy-level as the directory Model. In our case, the class body remains empty because all the important functionalities are already generically implemented in the super-class \TYPO3\CMS\Extbase\Persistence\Repository.

<?php

namespace MyVendor\SjrOffers\Domain\Repository;

use TYPO3\CMS\Extbase\Persistence\Repository;

class OrganizationRepository extends Repository
{

}

We create a \MyVendor\SjrOffers\Domain\Repository\OfferRepository exactly the same way but we will later extend it with own methods for accessing offers. It's very likely that we have to access the other objects for categories, regions and update data of contact information of certain persons independent of the offers or their organizations. Thus we define some additional Repositories for those objects for easier access from the Frontend.

Note

You have to resist the urge to define Repositories for each object and limit yourself to a minimal number of Repositories. Instead, you should define the access methods within the Aggregate-Root objects as find methods.

\TYPO3\CMS\Extbase\Persistence\Repository serves with the following methods which are of course accessible and overridable in the extending child derivations:

add($object)

Adds an object to the Repository which is then persistent in the sense of Domain-Driven Design. But be careful, it will not written (and enhanced with an UID) to the database before finishing the loop through the Extension, to be precise after the call of the method persistAll() of the PersistenceManager.

remove($object) and removeAll()

The opponent of add(). An object will be removed from the Repository and is gonna be deleted from the database after finishing the Extension's loop. The method removeAll() empties the whole Repository.

update($modifiedObject)

An existing object in the Repository will be updated with the properties of the given object. Extbase finds the to-be-updated object by the uid of the given object and throws an exception if it does not exist.

findAll() and countAll()

Returns all the Repository's objects that are currently persisted in the database. However, this slightly confusing behaviour is intended. Whereas findAll() returns an Array of objects the method countAll() only counts the currently persisted objects (if the database backend is of type SQL it just executes the query SELECT COUNT) and returns an Integer number.

findByProperty($value), findOneByProperty($value) and countByProperty($value)

Those three methods help by finding one or several objects and by counting all the objects that correspond to the given value. The substring Property must be replaced by the uppercase-written property name of the class that is managed by the Repository. The methods then only return the objects as well count the objects whose properties Property correspond to the given value. Whereas the method findByProperty() returns an Array of all the matching objects, the method findOneByProperty() only returns the first object that was found. That is, assuming that no certain sorting order was given, the order in which the objects were created in the Backend. Last but not least, the method countByProperty() returns the count of the objects that would be returned if findByProperty() was given the same value and is, of course, an Integer number.

createQuery()

In opposite to the methods above, this function does not manage objects in the Repository. Instead, it returns a Query object which can be helpful to assemble own queries to the Storage-Backend. The details for this procedure will be given in the following chapter.

Before accessing the defined objects on the Repository you need to tell Extbase on which pages on TYPO3's page tree (see below for TYPO3's concept of the page tree) it should seek and file the objects. Without any further definitions Extbase will use the page tree's root (the globe).

Generally there are three cases which need to be distinguished: Persisting a newly created object, reaccessing an existing object and updating the properties of an existing object. When creating a new object Extbase determines the destination pages in the following rule hierarchy:

<procedure>

• If, as already described in Chapter 4, the option source is checked then the objects will be searched in the corresponding pages

• If the TypoScript-Setup of the page contains the definition of plugin.tx_*extensionname*.persistence.storagePid with a comma-separated list of PIDs then those pages will be consulted.

• If the TypoScript-Setup of the page contains the definition of config.tx_extbase.persistence.storagePid with a comma-separated list of PIDs then those pages will be consulted.

• If none of the cases from above applies, then the root page will be consulted for the objects.

</procedure>

When insertion of new Domain objects happens, then the procedure will be as follows:

<procedure>

• If there's a TypoScript setup at plugin.tx_extensionname.persistence.classes.*FullClassName*.newRecordStoragePid with a single page value, then this is gonna be used.

• If there's a TypoScript setup at config. tx_extbase.persistence.classes.*FullClassName*.newRecordStoragePid with a single page value, the this is gonna be used.

• If none of the cases above apply, then the object will be inserted at the first item in the list of search pages. So to say, in the end the root page (the one with the globe) is gonna be used for insertion.

</procedure>

When updating the Domain objects their PID is not changed. However, you can implement the property pid in your domain object with its corresponding set- and get-methods. Then a domain object may be moved from one page to another by setting a new pid.

Note

Most occurring mistake for seemingly empty Repositories is a mis-configured Storage-PID. Thus, you should firstly evaluate the Template Module whether it is set correctly.

Besides of the options for setting the Page UID there exist two other possibilities for configuring the Persistence Layer: enableAutomaticCacheClearing and updateReferenceIndex. The option config.tx_extbase.persistence.enableAutomaticCacheClearing = 1 within the TypoScript setup leads to a deletion of the cache whenever the data is rewritten. This option is normally activated.

TYPO3's Page Tree

In TYPO3 each Content Element and Dataset which should be rendered in the Backend corresponds to a certain Page. Technically, a page is nothing more than a a Node Element or a leaf in the virtual Page Tree. Every page is associated with a unique Page ID (PID). Some of the pages are reachable via a URL and TYPO3 renders and delivers them (usually in HTML). For example, the URL https://example.org/index.php?id=123 requests the Page with the PID 123. In this case, the term Page has the meaning of being a Webpage. But there are other cases, e.g. a directory (SysFolder) or a separator which are used to save data in a clear and structured way. A special already existing PID is 0 which is used to refer to the root page (the one with the shiny globe).

Note

Usually, data sets will be saved into Folders in the Page Tree though the pages using those data sets will be somewhere else. If their cache should be cleared as well then you should set up their PIDs in the field TSConfig of the page's preferences of the directory. For example, out Offers will be shown on the pages with the PIDs 23 and 26 (let's say for a Single and a List View). Then we will configure the variable TCEMAIN.clearCacheCmd = 23,26 in the page preferences of the SysFolder. Then the cache of these pages will be cleared as well and changes of an offer will show up immediately.

Internally, TYPO3 manages an index of all relationships between two data sets the so-called RefIndex. Due to this index it's possible to show the number of associated data sets in the list module's column [Ref.]. By clicking on the number you get further information about the incoming and outgoing references of the dataset. This index is automatically updated when any data sets get edited. The configuration config.tx_extbase.persistence.updateReferenceIndex = 1 effects an update when data sets get edited in the Frontend though it is normally deactivated due to its huge effects on performance.

Before calling a Repository's methods they need to be instantiated at first with use of the ObjectManager or via dependency injection.

Dependency injection example from chapter 2

 /**
  * @var ProductRepository
  */
 private $productRepository;

 /**
  * Inject the product repository
  *
  * @param \MyVendor\StoreInventory\Domain\Repository\ProductRepository $productRepository
  */
 public function injectProductRepository(ProductRepository $productRepository)
 {
     $this->productRepository = $productRepository;
 }

Warning

Repositories are Singletons therefore there may only exist one instance of each class at one time of script-execution. If a new instance is requested, the system will prove whether an instance of the requested object exists and will instead of creating a new object return the existing one. This is ensured by using the dependency injection. Thus, never ever use the PHP syntax keyword new for creating a repository object because the objects that are placed there will not be automatically persisted.

Now you know all the basic tools for durable persistation and recovering of your objects. Extbase offers a lot more sophisticated functionalities for special needs because it happens quite frequently that the standard methods of saving and seeking data in a repository are not sufficient for the individual case. Thus Extbase let's you define individual requests without losing the existing abstractions of the existing persistence backend. Additionally, Extbase let's you use "foreign" data sources which are most often data tables of the same database.