how to use odata services to create model dynamically from manifest.json - odata

Question

I am very new to UI5, I am working on an application which requires me to create models based on the request made from the browser (client).
If I consume all the odata services beforehand & use them according to the request made, it will become too heavy unnecessarily.
is there any way, this can be done dynamically?

Answer 1

I think your question title and the question content might be contradictory so I am placing my suggestions separately.
how to use odata services to create model dynamically from manifest.json
In your manifest.json file, locate the "sap.app" section/property and then add a datasource as follows:
"dataSources": { //used data sources -> ui5-related information stored in sap.ui5 namespace (unique inside the app)
"modelalias": { //key is alias which is used below in e.g. sap.ui5 ...
"uri": "/sap/opu/odata/snce/PO_S_SRV;v=2/" , //mandatory; version is part of uri, e.g. ";v=2", default is 1
"type": "OData" , //OData (default)|ODataAnnotation|INA|XML|JSON
"settings": { //data-source-type-specific attributes (key, value pairs)
"odataVersion": "2.0" , //possible values: 2.0 (default), 4.0
"annotations": [ "equipmentanno" ], //filled e.g. for Smart Template
"localUri": "model/metadata.xml" //relative url to local metadata
"maxAge": 360 //time in seconds
}
}
To instantiate this model with the alias "mymodel", you can add an entry into the manifest.json under "sap.ui5" as follows:
"models": {
...
"mymodel": { //empty string "" is the default model
"preload": true; //indicator that the model will be created immediately after the manifest is loaded by component factory and before the component instance is created
"dataSource": "modelalias", //reference of dataSource under sap.app - only enhance it with more settings for UI5 if needed
"settings": {
}
}
},
Now the manifest file will instantiate "mymodel" based on your odata uri in "datasources" and then set the model onto your Component.js. So when your application starts, you can access the model in any controller using:
this.getOwnerComponent().getModel("mymodel")
If I consume all the odata services beforehand & use them according to
the request made, it will become too heavy unnecessarily. is there any
way, this can be done dynamically?
Your assumption is that creating a model will slow the app startup. This may not always be true since:
The model creation is very quick
Reading data is what takes time and model instantiation
ODataModels work asyncronously be default so calling .read or .write are operations that can be managed asynchronously
Special case: If you wish to pre-fetch all your data in advance (at startup) I would advise that you ensure that you utilize filters like $select, $top and $skip on your Gateway service to implement growing list like behavior.
Hope that helps you.
More information on manifest.json: Link
Growing List: Link
ODataModel Examples: Link