# Module API ## Simple Loading Below is a basic example for loading a template without any additional type schema: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const yamldata = ` parameters: message: Hello! definitions: body: template:

template: | {{> body}} `; fast.Template.loadYaml(yamldata) .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({message: "Hello world!"})); }); ``` > **Note:** If the example above were saved in a file named simpleLoading.js, then you could run it from the CLI with this command: `node simpleLoading.js` If a `Template` has been serialized to JSON (e.g., to send in an HTTP request), it can be deserialized with `Template.fromJson()`: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const yamldata = ` template: | {{message}} `; fast.Template.loadYaml(yamldata) .then(template => JSON.stringify(template)) .then(jsonData => template.fromJson(jsonData)) .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({message: "Hello world!"})); }); ``` `Template` does not provide a mechanism for loading a template from a file and, instead, needs to be paired with something like Node's `fs` module: ```javascript const fs = require('fs'); const fast = require('@f5devcentral/f5-fast-core'); const yamldata = fs.readFileSync('path/to/file', 'utf8'); fast.Template.loadYaml(yamldata) .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({message: "Hello world!"})); }); ``` ## Loading with Type Schema To support user-defined types, a `SchemaProvider` must be used. The `FsSchemaProvider` can be used to load schema from disk: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const templatesPath = '/path/to/templatesdir'; // directory containing types.json const schemaProvider = new fast.FsSchemaProvider(templatesPath); const yamldata = ` template: | {{virtual_port:types:port}} `; fast.Template.loadYaml(yamldata, schemaProvider) .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({virtual_port: 443}); }); ``` ## Using a TemplateProvider A higher-level API is available for loading templates via `TemplateProvider` classes. These classes will handle calling the correct load function (`Template.loadYaml()` vs `Template.loadMst()`) and can also automatically handle additional schema files. For example, to load "templates sets" (a directory containing template files) from a given directory, the `FsTemplateProvider` class can be used: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const templateSetsPath = '/path/to/templateSetsDir'; const templateProvider = new fast.FsTemplateProvider(templateSetsPath); templateProvider.fetch('templateSetName/templateName') .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({ var: "value", boolVar: false })); }); ``` If only a subset of the directories should be loaded as template sets, `FsTemplateProvider` provides an option to filter directories: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const templateSetsPath = '/path/to/templateSetsDir'; const setsToLoad = ['foo', 'bar']; const templateProvider = new fast.FsTemplateProvider(templateSetsPath, setsToLoad); templateProvider.fetch('templateSetName/templateName') .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({ var: "value", boolVar: false })); }); ``` A `FsSingleTemplateProvider` is provided as convenience for loading a single template set (instead of a directory of template sets): ```javascript const fast = require('@f5devcentral/f5-fast-core'); const templateSetPath = '/path/to/templateSet'; const templateProvider = new fast.FsSingleTemplateProvider(templateSetPath); templateProvider.fetch('templateSet/templateName') .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({ var: "value", boolVar: false })); }); ``` > **Note:** Despite loading a single template set, a template set name must still be provided when querying the provider. ## Template Data Files Sometimes it is desirable to keep a portion of a template in a separate file and include it into the template text. This can be done with parameters and the `dataFile` property: ```javascript const fast = require('@f5devcentral/f5-fast-core'); const templatesPath = '/path/to/templatesdir'; // directory containing example.data const dataProvider = new fast.FsDataProvider(templatesPath); const yamldata = ` definitions: var: dataFile: example template: | {{var}} `; fast.Template.loadYaml(yamldata, { dataProvider }) .then((template) => { console.log(template.getParametersSchema()); console.log(template.render({virtual_port: 443}); }); ``` The `FsDataProvider` will pick up on any files with the `.data` extension in the template set directory. When referencing the file in a template, use the filename (without the extension) as a key. Parameters with a `dataFile` property: * are removed from `required` * have their `default` set to the contents of the file * given a default `format` of `hidden` Additionally, the contents of the data file can be base64-encoded before being used as for `default` by setting the `toBase64` property to `true`: ```yaml definitions: var: dataFile: example toBase64: true template: | {{var}} ``` Similarly, if the data file is base64-encoded, it can be decoded using `fromBase64`. If both `toBase64` and `fromBase64` are set, then `toBase64` takes precedence.