feat(core): add field arg to hideExpression and expressionProperties

[intellix]

Add field argument to hideExpression and expressionProperties

fix #704

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What is the new behavior (if this is a feature change)?

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• A unit test has been written for this change.
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Other information:

[aitboudad]

could you please apply the same for expressionProperties

[intellix]

I think I managed it @aitboudad - LMK

[juristr]

awesome 💪 should we add a test for this as well?

[intellix]

Added a test for hideExpression but couldn't really see similar tests for expressionProperties. Also added a reference in expression-properties.md after finding it searching through the codebase

[aitboudad]

Thank you @intellix, expect 5.1 release next week.

[intellix]

Sure, thanks :) For the impatient:

https://github.com/ds300/patch-package
patches/@ngx-formly+core+5.0.4.patch

diff --git a/node_modules/@ngx-formly/core/fesm5/ngx-formly-core.js b/node_modules/@ngx-formly/core/fesm5/ngx-formly-core.js
index 7711dfb..09596cc 100644
--- a/node_modules/@ngx-formly/core/fesm5/ngx-formly-core.js
+++ b/node_modules/@ngx-formly/core/fesm5/ngx-formly-core.js
@@ -2204,7 +2204,7 @@ FieldExpressionExtension = /** @class */ (function () {
          */
         function () { return false; }));
         if (typeof expression === 'string') {
-            expression = evalStringExpression(expression, ['model', 'formState']);
+            expression = evalStringExpression(expression, ['model', 'formState', 'field']);
         }
         return parentExpression
             ? (/**
@@ -2212,7 +2212,7 @@ FieldExpressionExtension = /** @class */ (function () {
              * @param {?} formState
              * @return {?}
              */
-            function (model, formState) { return parentExpression() || expression(model, formState); })
+            function (model, formState, field) { return parentExpression() || expression(model, formState, field); })
             : expression;
     };
     /**
@@ -2275,7 +2275,7 @@ FieldExpressionExtension = /** @class */ (function () {
         function (v) { return "templateOptions." + v; }));
         for (var key in expressionProperties) {
             /** @type {?} */
-            var expressionValue = evalExpression(expressionProperties[key].expression, { field: field }, [field.model, field.options.formState]);
+            var expressionValue = evalExpression(expressionProperties[key].expression, { field: field }, [field.model, field.options.formState, field]);
             if (key === 'templateOptions.disabled') {
                 expressionValue = !!expressionValue;
             }
@@ -2319,7 +2319,7 @@ FieldExpressionExtension = /** @class */ (function () {
             return false;
         }
         /** @type {?} */
-        var hideExpressionResult = !!evalExpression(field.hideExpression, { field: field }, [field.model, field.options.formState]);
+        var hideExpressionResult = !!evalExpression(field.hideExpression, { field: field }, [field.model, field.options.formState, field]);
         /** @type {?} */
         var markForCheck = false;
         if (hideExpressionResult !== field.hide || ignoreCache) {
diff --git a/node_modules/@ngx-formly/core/lib/components/formly.field.config.d.ts b/node_modules/@ngx-formly/core/lib/components/formly.field.config.d.ts
index f69113d..8e88bc5 100644
--- a/node_modules/@ngx-formly/core/lib/components/formly.field.config.d.ts
+++ b/node_modules/@ngx-formly/core/lib/components/formly.field.config.d.ts
@@ -81,12 +81,12 @@ export interface FormlyFieldConfig {
     /**
      * Conditionally hiding Field based on values from other Fields
      */
-    hideExpression?: boolean | string | ((model: any, formState: any) => boolean);
+    hideExpression?: boolean | string | ((model: any, formState: any, field: FormlyFieldConfig) => boolean);
     /**
      * An object where the key is a property to be set on the main field config and the value is an expression used to assign that property.
      */
     expressionProperties?: {
-        [property: string]: string | ((model: any, formState: any) => any) | Observable<any>;
+        [property: string]: string | ((model: any, formState: any, field: FormlyFieldConfig) => any) | Observable<any>;
     };
     /**
      * This is the [FormControl](https://angular.io/api/forms/FormControl) for the field.

[juristr]

Just a consideration as I was applying the patch meanwhile until v5.1 gets released. The newly added param is actually a required one and I was wondering if we want to leave that or make it "optional" similar to the FormlyHookFn where it is optional as well:

ngx-formly/src/core/src/lib/components/formly.field.config.ts

Lines 235 to 237 in 1bea5a2

	export interface FormlyHookFn {
	(field?: FormlyFieldConfig): void;
	}

I'm mentioning this here as in my setup after upgrading to v5.1 it doesn't compile any more, because I manually did some manipulation of a formly config before giving it to the formly component where I directly invoked the hideExpression function.

...
// hide the checkbox when the according control is hidden dynamically
checkboxConfig.hideExpression = (model, formState) => {
  if (field.hideExpression instanceof Function) {
    return field.hideExpression(model, formState); // <<<<< BREAKS
  } else { 
    return false;
  }
};

Obviously TypeScript doesn't compile as now 3 params are expected. I don't see this as a big problem, as it's quite an edge case. Just wanted to mention that to you guys @aitboudad @intellix

[aitboudad]

@juristr I'll take care of it, Thanks!